Strongly coupled Fe-doped NiS2/MoS2 composite for high-efficiency water splitting

A strongly coupled Fe-doped NiS2/MoS2 composite was fabricated through an in situ induced dual confinement during the vapor vulcanization of precursors, exhibiting a significantly enhanced bifunctional HER/OER performance.

Research Progresses and Challenges of Flexible Zinc Battery

Flexible zinc batteries have great potential in wearable electronic devices due to their high safety, low cost, and environmental friendliness. In the past few years, a great deal of work on flexible zinc batteries has been reported, with exciting results. Therefore, many solutions have been proposed in electrode design and electrolyte preparation to ensure the desired flexibility without sacrificing the capacity. This paper reviews the recent progress of flexible zinc batteries. We discuss the differences between various anode materials, cathode materials, and electrolytes, introduce the differences of electrode preparation methods of active materials on flexible substrates and their influence on the performance of the battery. Finally, the challenges and future research trends of flexible zinc batteries in capacity and mechanical properties are pointed out.

Confined synthesis of MoS2 with rich co-doped edges for enhanced hydrogen evolution performance

Formamide-soluble solid-state ZnO as Zn source for synthesizing FeCo–NC with ultrahigh oxygen reduction reaction activity

Cost/time-efficient synthesis of highly dispersed M–N–C electrocatalysts was established using solid-state ZnO as new Zn source, rendering superior ORR (Eonset ∼ 1.05 V and E1/2 ∼ 0.92 V) and Al–air battery performance.

Oxygenated boron-doped carbon via polymer dehalogenation as an electrocatalyst for high-efficiency O2 reduction to H2O2

Single-atom Zn for boosting supercapacitor performance

A reliable gel polymer electrolyte enables stable cycling of rechargeable aluminum batteries in a wide-temperature range

Rational Construction of Fluffy CNT on Binary FeCo‐NC as High‐Efficiency S Host for Li−S Battery

Low-Cost Gel Polymer Electrolyte for High-Performance Aluminum-Ion Batteries

N-doped carbon nanoflower-supported Fe-N4 motifs for high-efficiency reduction of oxygen in both alkaline and acid

Formamide-derived “glue” for the hundred-gram scale synthesis of atomically dispersed iron–nitrogen–carbon electrocatalysts

Formamide-derived N-doped carbon was used as a “glue” for doping metal atoms on inexpensive carbon substrates for commercial Al–air battery applications.

Flexible carbon nanofiber film with diatomic Fe-Co sites for efficient oxygen reduction and evolution reactions in wearable zinc-air batteries

A ternary B, N, P-Doped carbon material with suppressed water splitting activity for high-energy aqueous supercapacitors

Porous carbon materials (PCMs) have been extensively investigated as electrode materials for supercapacitors, yet are severely hindered by low capacitance and energy density. Herein, we reported the efficient synthesis of a ternary B, N, P-doped PCMs (termed as BNP-C) via polymer dehalogenation strategy. The atomic contents of B, N, and P, as characterized by XPS, are 11.5, 1.1, and 0.8 %, respectively, yet intriguingly resulting in limited water splitting activity due to the overwhelmingly presented B dopant. This specific feature can be taken advantage of for effectively expanding the workable voltage window while maintaining large capacitances of aqueous supercapacitors (ASCs). Besides, the BNP-C exhibited porous 3D structure, hierarchical porous structure, and large surface area of 1118.5 m2 g-1, which simultaneously ensured the BNP-C-assembled ASC with superior capacitive performance. As confirmed by both Dunn and Trasatti methods, pseudocapacitance remarkably contributed ~44.9 and ~40.2 % respectively in overall capacitances for the BNP-C, which was mainly credited to the heavy decoration of B. In addition, the BNP-C symmetric ASC delivered very good long-term stability and high specific energy of 12.0 and 10.9 Wh kg-1 in acidic and alkaline electrolytes, respectively.

Assisting Atomic Dispersion of Fe in N-Doped Carbon by Aerosil for High-Efficiency Oxygen Reduction

Utilizing Zn as “fencing” agent has enabled the pyrolytic synthesis of atomically dispersed metal-nitrogen-carbon (AD-MNC) materials for broad electrocatalysis such as fuel cells, metal-air batteries, and water electrolyzers. Yet the Zn residue troubles the precise identification of the responsible sites in active service. Herein we developed a simple aerosil-assisted method for preparing AD-MNC materials to cautiously avoid the introduction of Zn. The combined analysis of extended X-ray absorption fine structure (EXAFS) and aberration-corrected high-resolution transition electron microscope verified the atomic dispersion of Fe species in the as-made Fe-NC sample with a well-defined structure of Fe-N4. Besides, the EXAFS studies indicated the formation of oxygenated Fe-N4 moieties (O-Fe-N4) after the removal of aerosil nanoparticles. Therefore, the immobilization of Fe atoms in carbon substrate was attributed to the heavily doping N and rich oxygen dangling species at aerosil surface. Electrochemical measurements revealed that the as-made Fe-NC material furnished with O-Fe-N4 moieties exhibited excellent oxygen reduction reaction (ORR) performance, characterized by individually indicating 22 mV higher half-wave potentials, with respect to commercial Pt/C catalyst. Density functional theory (DFT) calculations proposed that the O-dangling bond on Fe center, serving as a fifth coordination, could significantly boost the rate-limiting step of reductive release of *OH intermediates, leading to the enhancement of overall ORR performance.

Atomically Dispersed Fe-N4 Modified with Precisely Located S for Highly Efficient Oxygen Reduction

Immobilizing metal atoms by multiple nitrogen atoms has triggered exceptional catalytic activity toward many critical electrochemical reactions due to their merits of highly unsaturated coordination and strong metal-substrate interaction. Herein, atomically dispersed Fe-NC material with precise sulfur modification to Fe periphery (termed as Fe-NSC) was synthesized, X-ray absorption near edge structure analysis confirmed the central Fe atom being stabilized in a specific configuration of Fe(N3)(N–C–S). By enabling precisely localized S doping, the electronic structure of Fe-N4 moiety could be mediated, leading to the beneficial adjustment of absorption/desorption properties of reactant/intermediate on Fe center. Density functional theory simulation suggested that more negative charge density would be localized over Fe-N4 moiety after S doping, allowing weakened binding capability to *OH intermediates and faster charge transfer from Fe center to O species. Electrochemical measurements revealed that the Fe-NSC sample exhibited significantly enhanced oxygen reduction reaction performance compared to the S-free Fe-NC material (termed as Fe-NC), showing an excellent onset potential of 1.09 V and half-wave potential of 0.92 V in 0.1 M KOH. Our work may enlighten relevant studies regarding to accessing improvement on the catalytic performance of atomically dispersed M-NC materials by managing precisely tuned local environments of M-Nx moiety.

Electrochemical heavy metal removal from water using PVC waste-derived N, S co-doped carbon materials

Redeeming water from heavy metal contaminants has arisen global concerns due to water shortage and lax control on the discharge of heavy metal pollutants. Capacitive deionization (CDI) has emerged as a robust, energy-/cost-efficient technique for water treatment. Herein, we reported the simple N,S-codoped carbon materials (NS-C) from PVC plastic wastes as CDI electrode materials for the efficient removal of heavy metal ions (HMI). The NS-C exhibited large specific surface area (~1230 m2 g-1) and contained heavy heteroatom doping (~4.55 at.% N and ~13.30 at.% S). CDI electrode fabricated using NS-C showed very high removal efficiency (94-99%), high capacity (36-62 mg g-1), and good regeneration capability for the adsorption of various kinds of low-concentration heavy metals ions (including Fe2+, Co2+, Ni2+, Cu2+, Pb2+, and Cd2+). Moreover, PVC plastic wastes that are heavily accumulated in the environment and extremely hard to be decomposed and recycled were applied as carbon source in this study for the fabrication of NS-C, which further rendered the importance of our study to practically treating hazardous wastes (HMI pollutions) with wastes (PVC plastic wastes) in clean and efficient way.

Hierarchically Porous N, P-Codoped Carbon Materials for High-Performance Supercapacitors

Heteroatom-doped carbon materials have drawn enormous attention as high-performance electrode materials owing to their widely tunable surface properties and structures, yet their facile obtainments have been mostly hindered by complex synthesis routes and low heteroatom-doping efficiency. Herein, we showcase the simple synthesis of N, P co-doped carbon nanomaterials (NP-C) with beneficial pore hierarchy applying the dehalogenation of polyvinyl dichloride (PVDC) by KOH at room temperature and high-efficiency functionalization of remained carbon skeleton using melamine and NaH2PO2. The concentration and configuration of N and P heterodopants can be simply tuned by altering the calcination temperatures. The resulted material prepared at 700 °C delivers superior capacitive performance: a high specific capacitance (Cs) of 367.5 F g-1 at 0.5 A g-1 and a capacity retention of ~95% after 10000 cycles at 10 A g-1. As analyzed by Dunn method, ~27.8% of complete capacitance is contributed by pseudocapacitive charge storage, which thanks to the high-content N (~6.3 at.%) and P (1.3 at.%) doping. Our facile preparation method can be potentially extended to the synthesis of more binary and ternary heteroatom-doped carbon nanomaterials for broad electrochemical applications.

Hierarchically porous carbon from foamed Mg chelate for supercapacitor and capacitive deionization

Pore hierarchy in electrode materials has been verified by many literatures that is capable of greatly facilitating the mass transportation between internal active surface and bulk solution, which is critical for capacitive applications such as supercapacitors and capacitive deionization. Herein, by applying in situ foamed Mg chelates as precursors, we managed the scalable fabrication of hierarchically porous carbon (HPC) materials. Particularly, citric acid first reacted with magnesium nitrate to form Mg chelate while the generated gaseous HNO3 molecules bubbled the intermediate carbon framework to produce abundant open pores. The as-made precursors were then submitted to potassium hydroxide activation for high carbonization degree and rich meso-/micropores. Electrochemical measurements revealed that the optimized sample (HPC-2) exhibited very high specific capacitance of 213.5 F g-1 (at 1.0 A g-1) in 1.0 mol L-1 neutral NaCl solution and high rate capability of ~67.5 % at 10.0 A g-1. Furthermore, it showed impressive capacitive deionization performance regarding high removal efficiency (67.1%), large capacity (1865.7 mg g-1 in 2200 mg L-1 NaCl solution), and robust cycling stability.

Ultrasmall NiFe layered double hydroxide strongly coupled on atomically dispersed FeCo-NC nanoflowers as efficient bifunctional catalyst for rechargeable Zn-air battery

Atomically dispersed FeCo-NC material with 3D flower-like morphology was investigated as unique substrate for the controllable deposition of ultrasmall NiFe layered double hydroxide nanodots (termed as NiFe-ND) to simultaneously promote the sluggish kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The size-limiting growth of NiFe-ND (~4.0 nm in diameter) was realized via the confinement of the 3D flower-like mesoporous structure and the rich N/O functionality of FeCo-NC. Benefiting from the distinctive structure with the simultaneous maximum exposure of both OER and ORR active sites, the NiFe-ND/FeCo-NC composite showed a 0.85 V ORR half-wave potential and a 1.66 V OER potential in 0.1 M KOH at 10.0 mA cm-2. In-situ Raman analysis suggested the origin of OER activity to be the Ni sites on NiFe-ND/FeCo-NC. Moreover, the NiFe-ND/FeCo-NC-assembled Zn-air batteries (ZAB) exhibited a very small discharge-charge voltage gap of 0.87 V at 20 mA cm-2 and robust cycling stability. Furthermore, the NiFe-ND/FeCo-NC composite was also applicable for fabricating all-solid-state ZAB to power wearable electronics and rendered superior cycling stability under deformation. Our work may enlighten the new applicable branch of atomically dispersed metal-nitrogen-carbon materials as unique substrate for fabricating multifunctional electrocatalysts.

Sacrificial carbon nitride-templated hollow FeCo-NC material for highly efficient oxygen reduction reaction and Al-air battery

Solid-phase templates are commonly used for building hollow-structured carbon materials (CMs) but often demand post treatments to remove templates. Herein, we develop an efficient and general method to construct hollow carbonaceous structure via the templating of sacrificial carbon nitride (termed as f-NC) without post treatment. The f-NC template can be decomposed under high-temperature annealing, additionally, it can serve as N source to enrich the N content. Applying f-NC templates, we manage the synthesis of hollow-structured highly dispersed binary FeCo-nitrogen-carbon material (termed as f-NC@FeCo-NC). Its hollow feature is confirmed by direct observation using HRTEM. Meanwhile, Fe/Co in oxidation states have been verified uniformly distributing in heavily N-doped CMs (N content ~ 13.2 at.%). The resulted f-NC@FeCo-NC, as examined by electrochemical measurements, exhibits highly efficient performance toward oxygen reduction reaction (ORR) in alkaline medium. It respectively shows much enhanced onset and half-wave potentials of 1.01 and 0.89 V relative to the FeCo-NC that is obtained without f-NC, in contrast, 20 wt.% Pt/C shows 0.95 V onset potential and 0.83 V half-wave potential. The f-NC@FeCo-NC catalyst also shows excellent performance when applied as cathode material for Al-air battery, which possesses a high open circuit voltage of 1.91 V and a high peak power density of 241 mW cm-2. We believe this sacrificial f-NC can be applied as general template for the fabrication of other hollow-structured carbon-based materials for broad electrochemical applications.

Pyrolysis-free formamide-derived N-doped carbon supporting atomically dispersed cobalt as high-performance bifunctional oxygen electrocatalyst

Non-precious metal-nitrogen-carbon (MNC) electrocatalysts have gained tremendous attention as promising electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the most applicable strategies for the synthesis of MNC materials heavily rely on pyrolysis treatment, which may easily lead to metal aggregation and subsequent degradation of catalytic performance. Herein, we developed a pyrolysis-free strategy for preparing MNC materials, which was demonstrated by achieving ultrathin cobalt-nitrogen-carbon (CoNC) layer with dense atomically dispersed cobalt sites depositing on graphene oxide (GO) via simple treatment of Co salt and GO in formamide. The formamide-derived CoNC layer deposited on GO (termed as f-CoNC/GO) could be controlled in 1~2 nm thick. Remarkably, the f-CoNC/GO composite without pyrolysis exhibited excellent bifunctional performance toward ORR and OER, which was attributed to the dense atomically dispersed Co-Nx sites and improved conductivity by GO substrate. Furthermore, the f-CoNC/GO-assembled rechargeable Zn-air battery showed highly efficient and stable performance, demonstrating our pyrolysis-free method to be straightforward, cost-effective, and feasible for the scalable production of MNC electrocatalysts.

Hierarchical porous N,S‐codoped carbon material derived from halogenated polymer for battery applications

Herein, a hierarchically porous N, S-co-doped carbon material (named as NS-C) was efficiently fabricated from halogenated polymer to meet the targets of the low-cost anode and cathode materials for Li-based batteries. Thanks to its large N (~5.4 at.%) and S (~1.1 at.%) contents, large specific surface area (~1510 m2 g-1), and beneficial pore hierarchy, the NS-C exhibited superior bifunctional performance as anode material and S host for Li-S cathode. The NS-C/sulfur composite (named as S@NS-C) delivered a large capacity of 1125 mAh g-1 at 0.1 C and maintained a capacity of 401 mAh g-1 at 5 C. A continuous long-term use for 200 cycles at 2 C achieved large capacity retention of 80.5%. Furthermore, the NS-C could also serve as anode material for stable Li-ion storage with large capacity, showing very limited capacity fading for over 1000 cycles at both 0.1 and 1.0 A g-1. Moreover, considering the huge amount of halogenated polymer plastic wastes buried, burned, or discarded directedly in the environments, our developed route of simple conversion of halogenated polymers into Li-ion battery anode and S host for Li-S battery cathode is advantageous for both environmental protection and Li-based battery industry.

Binary FeCo-N-doped carbon/carbon nanotube composites for efficient oxygen reduction and high-performance aluminum-air battery

Aluminum-air batteries (AAB) have been expected as one promising energy technology for next-generation electrical vehicles owing to their low costs, light weights, high specific energy, environmental benignity and mechanical rechargeability. Yet currently, efficient catalytic materials for air cathodes are mostly based on expensive and scarce precious metal Pt, which have severely impeded the implantation of AAB. Herein, a series of non-precious binary FeCo-nitrogen-doped carbon (FeCo-NC) materials with heavily loaded Fe/Co species and in-situ generated interconnected carbon nanotube (CNT) were synthesized from cost-effective materials. With merits of dense active sites, largely exposed surface area, and good electron/ionic conductivity, the as-made binary FeCo-NC with optimal synthetic parameters exhibit excellent oxygen reduction reaction performance in alkaline solution, rendering high onset potential of 1.05 V and half-wave potential of 0.91 V, which surpasses those of Pt/C by 50 and 40 mV, respectively. Remarkably, the as-assembled AAB cathode delivers an exceptional open-circuit voltage of 1.88 V and a specific power of 188 mW cm-2, and additionally maintained high discharge voltage of 1.70 V at the current density of 10.0 mA cm-2. Our work renders a new type of high-performance air cathode material for AAB implantation.

Hierarchical peony-like FeCo-NC with conductive network and highly active sites as efficient electrocatalyst for rechargeable Zn-air battery

Carbon materials featuring hierarchical pores and atomically dispersed metal sites are promising catalysts for energy storage and conversion applications. Herein, we developed a facile strategy to construct functional carbon materials with a fluffy peony-like structure and dense binary FeCo-Nx active sites (termed as f-FeCo-CNT). By regulating the metal content in precursors, a 3D interconnected conductive carbon nanotubes network was in-situ formed throughout the atomically dispersed FeCo-NC matrix during pyrolysis. Taking advantage of rich pore hierarchy and co-existence of highly active FeCo-Nx sites and beneficial FeCo alloy nanoparticles, the f-FeCo-CNT material exhibited excellent bifunctional performance towards oxygen reduction/evolution reactions (ORR/OER) with respect to the atomically dispersed FeCo-NC (SA-f-FeCo-NC) and commercial Pt/C+RuO2 mixture, surpassing the SA-f-FeCo-NC with a 20 mV higher ORR half-wave potential and a 100 mV lower OER overpotential (at 10.0 mA cm-2). Remarkably, the f-FeCo-CNT-assembled Zn-air battery (ZAB) possessed a maximum specific power of 195.8 mW cm-2, excellent rate capability, and very good cycling stability at large current density of 20.0 mA cm-2. This work provides a facile and feasible synthetic strategy of constructing low-cost cathode materials with excellent comprehensive ZAB performance.

Boosting the bifunctional oxygen electrocatalytic performance of atomically dispersed Fe site via atomic Ni neighboring

An advanced zinc air battery with nanostructured superwetting electrodes

Molten alkaline synthesis of highly porous carbon from calcium carbide

Carbide-derived carbons (CDC) represent a kind of typical and fascinating porous carbon materials (PCM) for broad applications but demand hazardous chlorine to fulfil the conversion into carbon. Here in this study, we report the facile fabrication of PCM with rich porosity from mild molten alkaline-treated calcium carbide (CaC2). Resulted PCM under optimized synthesis conditions exhibited large specific surface area (~ 839 m2 g-1) and specific capacitance (403 F g-1 at current density of 0.5 A g-1). Meanwhile, fairly good rate capability of retaining over 63% capacitance at large current density of 5 A g-1, and robust cycling performance (~5% fading after 5000 cycles at high rate of 5 A g-1) can be also obtainable. Our study rendered a simple but effective method to utilize CaC2 as carbon source and may have broad applications such as adsorbents, anode materials for Li/Na-ion batteries.

A density functional theory study of the oxygen reduction reaction on the (111) and (100) surfaces of cobalt(II) oxide

Density functional theory calculations were employed to investigate the electrochemical oxygen reduction reaction on the (111) and (100) surfaces of cobalt(II) oxide. Different mechanisms were applied to evaluate the oxygen reduction reaction performance of cobalt(II) oxide structures in terms of the Gibbs free energy and density of states. A variety of intermediate structures based on associative and dissociative mechanisms were constructed and optimized. As a result, we estimated the catalytic activity by calculating the free energy of the intermediates and constructing free energy diagrams, which suggested that the oxygen reduction reaction Gibbs free energy on cobalt(II) oxide (111) and (100) surfaces based on the associative mechanism is smaller than that based on the dissociative mechanism, demonstrating that the associative mechanism should be more likely to be the oxygen reduction reaction pathway. Moreover, the theoretical oxygen reduction reaction activity on the cobalt(II) oxide (111) surface was found to be higher than that on the cobalt(II) oxide (100) surface. These results shed light on the rational design of high-performance cobalt(II) oxide oxygen reduction reaction catalysts.

A general route via formamide condensation to prepare atomically dispersed metal–nitrogen–carbon electrocatalysts for energy technologies

Single-atom electrocatalysts (SAECs) have gained tremendous attention due to their unique active sites and strong metal-substrate interactions. However, current synthesis of SAECs mostly relies on costly precursors and rigid synthetic conditions, and often results in very low content of single-site metal atoms. Herein, we report an efficient synthesis method to prepare metal-nitrogen-carbon (M-NC) SAECs based on formamide condensation and carbonization, featuring a cost-effective general methodology for the mass production of SAECs with high loading of atomically dispersed metal sites. Seven types of single-metallic M-NC (Fe, Co, Ni, Mn, Zn, Mo and Ir), two bi-metallic (ZnFe and ZnCo) and one tri-metallic (ZnFeCo) SAECs were synthesized to demonstrate the generality of the methodology developed. Remarkably, these M-NC SAECs can be coated onto various supports with an ultrathin layer as pyrolysis-free electrocatalysts, among which the carbon nanotube-supported Fe-NC and Ni-NC SAECs showed high performance for O2 reduction reaction (ORR) and CO2 reduction reaction (CO2RR), respectively. Furthermore, the pyrolysis products of supported M-NC can still render isolated metallic sites with excellent activity, as exemplified by the bi-metallic FeCo-NC SAEC, which exhibited outstanding ORR performance in both alkaline and acid electrolytes by delivering ~70 and ~20 mV higher half-wave potentials than that of commercial 20 wt.% Pt/C, respectively. This work offers a feasible approach to design and manufacture SAECs with tuneable atomic metal components and high density of single-site metal loading, and thus may accelerate the deployment of SAECs for various energy technology applications.

基于有机脱卤策略制备碳材料

张国新博士参加了第31届中国化学会年会（杭州），并作了题为“基于有机脱卤策略制备碳材料”的报告。

Ultrathin atomic Mn-decorated formamide-converted N-doped carbon for efficient oxygen reduction reaction

It is of great importance to control the thickness of catalytic components to enable maximum catalyst utilization and strong catalyst-substrate interaction since electrocatalytic reactions occurring at the interface of catalysts containing one or two-atom thick active layer. Herein, we achieved the ultrathin deposition of 2.5±0.2 nm active layer containing atomically dispersed Mn-nitrogen-carbon (Mn-NC) materials on conductive carbon nanotube (CNT) via solvothermal treatment of formamide and Mn salt, and applied the as-made Mn-NC/CNT composite without pyrolysis directly as catalysts for oxygen reduction reaction (ORR). The atomic dispersion of Mn species in multiple nitrogen surroundings has been confirmed by combining High-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photon spectroscopy. The as-prepared formamide-converted Mn-NC/CNT composite, used for catalyzing ORR, exhibited highly comparable performance in alkaline media relative to that of 20 wt.% Pt/C by showing high onset potential and half-wave potential (E1/2) of 0.91 V and 0.83 V (vs RHE), respectively. Density functional theory (DFT) calculations further suggested that the Mn-N moieties are capable of efficiently accelerating the release of *OH intermediates under more reductive potential, thus exhibiting advanced ORR performance.

Interconnected polypyrrole nanostructure for high-performance all-solid-state flexible supercapacitor

Rational design of conductive polymer-based supercapacitor (CPSC) by integrating three-dimensional (3D) interconnected electrode materials with porosified electrolyte is of great potential to simultaneously increase the specific capacitance and rate capability of CPSC device. Herein, we describe for the first time a prototype of all-solid-state CPSC using 3D interconnected fibrous polypyrrole (PPy) and 3D porosified electrolyte. The as-made PPy was characterized to possess excellent electron conductivity (~7.8 S·cm-1), 3D interconnected structure, providing fast electron/ion transportation pathway to accelerate the kinetics of interfacial pseudocapacitive reactions. The symmetric PPy-based CPSC device initially delivered a high specific capacity up to 505 mF·cm–2 at current stream of 2.0 mA·cm–2 and was capable of retaining 50% capacitance (~250 mF·cm–2) at high rate (20.0 mA·cm–2). Meanwhile, an improved energy density of 44.9 μWh·cm-2 at power of 8 mW·cm-2 was achieved. In addition, PPy-CPSC exhibited excellent flexible performance, no obvious degradation of capacitive performance was observed for PPy-CPSC device under bent or twisted.

Tuning Electronic Structure of NiFe Layered Double Hydroxides with Vanadium Doping toward High Efficient Electrocatalytic Water Oxidation

A highly-efficient oxygen evolution electrode based on defective nickel-iron layered double hydroxide

Using an AlCl3/Urea Ionic Liquid Analog Electrolyte for Improving the Lifetime of Aluminum-Sulfur Batteries

Polyvinylchloride-derived N, S co-doped carbon as an efficient sulfur host for high-performance Li–S batteries

The intrinsic polysulfide shuttle in lithium-sulfur (Li-S) batteries have significantly limited their practical applications. Conductive carbon materials with heteroatom doping and rich porosity are the most common tactics for the effective prevention of polysulfide shuttle but usually obtained with high costs and tedious procedures. Herein, we managed to obtain highly porous N, S-codoped carbon materials through treating inexpensive PVC (a type of widely applicable plastic) with KOH. The as-resulted NS-C was revealed to be highly efficient hosts for sulfur, achieving large reversible capacities of 1205 mAh g-1 and 836 mAh g-1 at 0.1 C and 1.0 C, respectively. More importantly, a high capacitance retention of ~66% was achieved after 500 cycles at 1.0 C. The significantly enhanced cycling performance was mainly ascribed to both hierarchically porous structure and heavy N, S co-dopants, which respectively provided physical blocks and chemical traps for the efficient immobilization of intermediate lithium polysulfides. Combining the facile route for converting PVC plastics into value-added carbon materials with its high performance for hosting sulfur, we may safely envision a big step for the practical implantation of Li-S battery.

A general approach to homogeneous sub-nanometer metallic particle/graphene composites by S-coordinator

Topotactic conversion of calcium carbide to highly crystalline few-layer graphene in water

The reaction of calcium carbide (CaC2) with water to produce acetylene is common in industrial productions, but its side reaction, removal of calcium from CaC2 (also termed as de-Ca) to fabricate highly graphitic carbon is highly overlooked. Herein, we reported the synthesis of high-crystalline few-layered graphene by controlling the reaction of tetragonal-phased CaC2 with water at room temperature (20~25℃). The resultant carbon materials were revealed to be highly graphitic, in ~3 nm thick, containing >93 at.% carbon. Raman evidenced their low defect contents of ~0.07 defect (D)/graphitization(G) ratio. HRTEM further verified its high graphitization degree. A formation mechanism was proposed that the C_2^(2-) "dumbbells" donate their electrons to nearby oxidative species, e.g. H+ in water, followed by the topotactic cross-linking to form conjugated sp2-carbon network. Furthermore, the capability of CaC2 reducing and re-assembly into graphitic carbon was clearly evidenced by reacting with Ag+ in non-aqueous solvent, resulting in larger quantity of graphene materials as well as small-sized Ag nanoparticles.

Dehalogenated carbon-hosted cobalt-nitrogen complexes for high-performance electrochemical reduction of oxygen

Metal-nitrogen-complexed carbon (MNC) materials have received tremendous attention due to their extraordinary catalytic performance and widely spread applications in the fields of electrocatalysis especially oxygen reduction reaction (ORR). Yet currently, the efficient method for mass production of MNC electrocatalysts under low costs is still lacking. Herein, we explored a facile low-cost route to construct Co-N-decorated carbon (Co-N-C) materials that were capable of delivering competitively high ORR performance toward referring to commercial 20 wt.% Pt/C catalyst (comparable activity, higher long-term cycling stability and tolerance to methanol contamination). The Co-N-C electrocatalysts were mainly facilitated via the efficient dehalogenation of polyvinyl dichloride (PVDC) or polyvinyl chloride (PVC) and in situ doping with nitrogen and cobalt ions under mild conditions. Besides the rendered promising electrocatalysts for ORR, our developed method may be capably of converting the halogenated polymeric plastic wastes that are massively accumulated in our environment into value-added carbon-based catalytic materials.

Converting Polyvinyl Chloride Plastic Wastes to Carbonaceous Materials via Room-Temperature Dehalogenation for High-Performance Supercapacitor

Polyvinyl chloride (PVC) plastics are widely applicable in our daily life, however, their over uses and extremely high toughness to be recycled/disposed have caused serious challenges to our environment. In this study, we proposed an effective and green method to convert PVC plastics to carbonaceous materials via KOH-assisted room-temperature dehalogenation, along with the formation of clean by-products of KCl and H2O.Thereof, high-quality porous carbon materials could be obtainable through performing simple annealing on the abovementioned carbonaceous materials. The as-resulted carbon materials derived from PVC plastics were fabricated into electrodes for supercapacitor application. Remarkably, the porous carbon material derived from plastic wrap (PW-C) exhibited excellent performance for aqueous symmetric supercapacitor. The specific capacitance reached up to 399 F g-1 and 363 F g-1 (at 1.0 A g-1) in 6.0 mol L-1 KOH and 1.0 mol L-1 H2SO4 electrolytes, respectively. Meanwhile, PW-C performed very good rate capability and cycling stability in both electrolytes. Therefore, our developed method is capable of treating PVC plastic wastes safely and efficiently and converting them into valued-added porous carbon electrode materials, which may attract very soon practical implantations.

Powerful Dehalogenation Tool: A Simple Route To Graft Carbon Materials With Well-Defined Open Pores

hese findings are described in the article entitled Fabricating Hierarchically Porous Carbon with Well-Defined Open Pores via Polymer Dehalogenation for High-Performance Supercapacitor recently published in the journal Applied Surface Science. This work was conducted by Mei Guo, Yu Li, Kewen Du, Chaochao Qiu, Gang Dou, and Guoxin Zhang from Shandong University of Science and Technology.

Toward High-Voltage/Energy Symmetric Supercapacitors via Interface Engineering

This chapter includes elaborately selected recent literatures on electrochemical energy storing in symmetric supercapacitors (SSCs) with high operating voltages (voltage>1.6 V) and high specific energy. SSCs are a typical sort of electrochemical capacitors with larger energy density than conventional capacitors, by involving electrode materials with stable interfaces (for instance, nitrogen-doped carbon materials) and electrolytes with wide safe potential window (for instance, ionic liquids), they can supply competitive energy relative to batteries. Fundamentals of SSCs are first introduced, aiming at clarifying some critical interfacial phenomenon that are critical to enhance overall capacitive performance. State-of-the-art SSCs are included as demonstrations from the aspects of both enhanced capacitances and expanded voltages. We also provide a few feasible strategies for the design high-voltage/-energy SSCs such as using inactive electrode materials.

Fabricating hierarchically porous carbon with well-defined open pores via polymer dehalogenation for high-performance supercapacitor

Improving specific energy under ultrahigh power has long been pursued as a challengeable topic for supercapacitors (SCs). In this work, hierarchically porous carbon (HPC) electrode materials with well-defined meso-/macro-pores are reported via the dehalogenation reaction of polyvinyl fluoride (PVDF) by NaNH2. The pore hierarchy is mainly formed because of the coupled effects from NaNH2 activation and the template/bubbling effects from byproducts. Both electron microscopy studies and Brunauer–Emmett–Teller (BET) measurements confirm that the structures of HPC samples contain multiple-scale pores assembled in a hierarchical pattern and most of their volumes are contributed by mesopores. Aqueous symmetric supercapacitors (ASSCs) were fabricated using HPC-M7 electrode materials, achieving an ultrahigh specific energy of 18.8 Wh kg-1 at specific power of 986.8 W kg-1. Remarkably, at the ultrahigh power of 14.3 kW kg-1, the HPC-ASSCs still output a very high specific energy of 16.7 Wh kg-1, which means the ASSCs can be charged or discharged within 4 s. The outstanding rate capacitive performance is benefited from the hierarchical porous structure that allows highly efficient ion diffusion.

Room-temperature rapid synthesis of metal-free doped carbon materials

Heteroatom doped carbon materials (DCM) have gained tremendous attention due to their highly-promising applications as well as low costs, therefore, time-/cost-/operation-effective fabrication of doped carbon materials holds great meanings to both scientific and practical fields. Here in this study, metal-free DCM could be fabricated rapidly (

Cobalt-Embedded Nitrogen-Doped Carbon Nanotubes as High-Performance Bifunctional Oxygen Catalysts

Enhancing Oxygen Reduction Activity by Exposing (111) Facets of CoFe2 O4 Octahedron on Graphene

Tuning the wettability of carbon nanotube arrays for efficient bifunctional catalysts and Zn–air batteries

The wettability of 3D carbon nanotube arrays (CNTAs) was tuned by controlling the nitrogen doping degree, and superhydrophilic nitrogen-doped CNTAs were obtained for anchoring transition metal oxides as bifunctional non-Pt electrocatalysts for high-performance zinc–air batteries.

A two-volt aqueous supercapacitor from porous dehalogenated carbon

Aqueous supercapacitors were among the most promising techniques for clean and renewable energy storage yet limited by their low specific energy arisen from water splitting issue. Herein, water splitting-inactive electrode materials of mesoporous carbon were fabricated through the dehalogenation of polyvinylidene fluoride (PVDF) by sodium ethoxide (EtONa). The as-generated EtOH and NaF have been demonstrated to facilitate the formation of hierarchical porous carbon based on the bubble and templating effects. Due to the full dehalogenation, the resulted carbon materials acquired high carbon contents where the unfavorable alien dopants are absent. The resulted porous dehalogenated carbon materials were applied as electrode materials for the aqueous supercapacitor neutral electrolyte. The as-proposed significantly suppressed water-splitting activity has been addressed in the electrochemical system. The open circuit voltage (OCV) could be therefore safely expanded to 2.0 V. Over 94.0 % of capacitance is also maintained after cycling 5,000 times at 5.0 A/g. Our strategy that utilizes water-splitting inactive electrode materials to expand working window of aqueous supercapacitor may enlighten the design of materials for aqueous supercapacitor with higher OCV over 2.0 V.

Fabricating Sulfur/Oxygen Co-Doped Crumpled Graphene for High-Performance Oxygen Reduction Reaction Electrocatalysis

Herein, defect-rich graphene oxide with crumpled form was fabricated via the fast thermal expansion of H2SO4-intercalated graphite oxide. The fast removal of intercalated H2SO4 molecules and by-product gases result in the formation of crumpled edges while the partial reduction of H2SO4 leads to a large amount of defects and minor S doping (S~0.55 at%). The expanded graphene oxide (CGO) with crumpled form and rich defects was applied as electrode materials for the oxygen reduction reaction (ORR), and very high ORR performance was observed in 0.1 mol L-1 KOH, exhibiting an onset potential of 0.92 V, a half-wave potential of 0.83 V, and a roughly 5.68 mA cm-2 limiting current density with catalyst loading of 0.1274 mg cm-2. Our work provides reliable GO-based catalyst materials for ORR; moreover, it may enlighten one type of high-activity sites for ORR: defects on crumpled edges.

Polymer Dehalogenation-Enabled Fast Fabrication of N,S-Codoped Carbon Materials for Superior Supercapacitor and Deionization Applications

Doping carbon materials (DCM) with multiple heteroatoms hold broad interests in electrochemical catalysis and energy storage but require several steps to fabricate, which hinder their practical applications. In this study, a facile strategy was developed to fabricate multiple DCM via room-temperature dehalogenation of polyvinyl dichloride (PVDC) with the presence of dehalogenation agent KOH and different doping sources. N, S-codoped carbon materials (NS-DCM) were demonstratively obtained using two heteroatom doping sources (dimethylformamide for N doping and dimethylsulfoxide for S doping). Afterwards, the precursive room-temperature NS-DCM with intentionally overdosed KOH were submitted to inert annealing in order to obtain large specific surface area and high conductivity for electrochemical applications. Remarkably, NS-DCM annealed at 600 °C (600-NS-DCM), with 3.0 at% N and 2.4 at.% S revealed by XPS measurement, exhibited very high specific capacitance of 427 F g-1 at 1.0 A g-1 in acidic electrolyte and maintained ~60 % of capacitance at ultrahigh working current density of 100.0 A g-1. Furthermore, capacitive deionization (CDI) measurements revealed that 600-NS-DCM possessed an impressive desalination capacity of 32.3 mg g-1 in 40.0 mg L-1 NaCl, and very good cycling stability. Our strategy of fabricating DCM with multiple heteroatoms codoping can be extended to the synthesis of various carbon materials for broad electrochemical applications.

Interfacial dehalogenation-enabled hollow N-doped carbon network as bifunctional catalysts for rechargeable Zn-air battery

Promoting oxygen reduction and evolution reactions using effective catalysts hold broad significance for clean energy utilization. In this work, hollow N-doped carbon networks (N-CNs) were fabricated via interfacial dehalogenation of polyvinyl dichloride (PVDC) on 2D CoAl-layered double hydroxide (LDH) with the presence of N source. BET results revealed that as-made N-CNs had very large specific surface area (SSA, 550.4 m2 g-1 for 900℃-annealed N-CN (N-CN9)) and abundant pore hierarchy. Additionally, interconnected graphitic carbon walls, forming separated cells, can ensure high electrical conductivity, which were formed after acid-leaching of metallic components. Remarkably, N-CN9 showed excellent bifunctional activities towards oxygen reduction and evolution reactions. Moreover, N-CN9 assembled Zn-air battery (ZAB) exhibited an open circuit voltage of 1.35 V under applied current density of 1.0 mA cm-2, which is highly comparable to that of PtRu/C catalyst. Moreover, due to the pore hierarchy and large SSA, N-CN9-ZAB possessed much better rate capability and cycling stability than that of PtRu/C-ZAB.

Scalable fabrication of hierarchically porous N-doped carbon electrode materials for high-performance aqueous symmetric supercapacitor

Nowadays, hierarchical porosity of electrode materials have attracted numerous attention due to allowing the smooth mass transportation and capability of improving the rate performance of electrochemical applications. In this study, hierarchically porous N-doped carbon (HPDC) materials were fabricated in a facile and scalable way via the dehalogenation of polyvinyl dichloride (PVDC) and applied as electrode materials for assembling symmetric aqueous supercapacitors. The resulted supercapacitors were found having a very high specific energy of 21.5 Wh K g-1 in 1.0 M Li2SO4 with a safe operating voltage (OV) of 1.8 V. The enhanced capacitive performance was ascribed to both the HPDC’s abundant pore hierarchy with a large accessible surface area and also the applicable neutral electrolyte with a wide stable potential. Besides the potentially scalable production of hierarchically porous carbon materials with high capacitive performance, our work may also envision that other halogenated polymer such as polyvinyl chloride (PVC) and its wastes can be easily converted into useful carbon materials via our developed dehalogenation strategy.

Thin sandwich graphene oxide@N-doped carbon composites for high-performance supercapacitors

Compositing graphene oxide (GO) with controllable secondary components is of great significance to achieve high-level physico-chemical properties of carbon materials. In this study, thin sandwich composites of GO and N-doped carbon (GO@NdC) were fabricated through a controllable deposition of polyvinyl dichloride (PVDC)-dehalogenated carbon on GO, which was ensured by the high affinity between PVDC and GO. The thin deposited carbon layers on GO could achieve the thickness of 1.0 to 2.0 nm. Considering dehalogenated carbon was verified to be highly reactive for coupling alien elements, the overall N content of ~7.0 at.% was obtained with the addition of N source of melamine. Meanwhile, byproducts of EtOH and NaCl could in situ tune the composite into open 3D structure, efficiently preventing thin layered composite from re-stacking. After activation by KOH, GO@NdC further performed hierarchical pore structure and large specific surface area. Remarkably, KOH-activated GO@NdC exhibited a high specific capacitance of ~354 F g-1 and capacitance retention of >65 % (at 10.0 A g-1). Finally, GO@NdC symmetric supercapacitor also achieved a high specific energy of ~11.8 Wh Kg-1 in aqueous alkaline electrolyte.

Unconventional Carbon: Alkaline Dehalogenation of Polymers Yields N-Doped Carbon Electrode for High-Performance Capacitive Energy Storage

Polymers are important precursors for the fabrication of carbon materials. Herein, instead of conventional polymers which contain N, O, or S, halogenated polymers were explored as another type of precursor for the synthesis of high-quality carbon materials. We found the halogen elements (F, Cl) connecting to vinylidene were highly reactive; the defunctionalization can take place a few seconds at room temperature by simple hand grinding when aided with strong inorganic alkaline. Simultaneously, dopants are highly welcomed at the halogen element-leaving sites and can be transformed into stable capacitive sites for ions. By using mixed dehalogenation agents of NaOEt and KOH, we managed to create abundant hierarchical pores (macro/meso-/micropore) in the doped carbon matrix for fast mass transportation. Very high capacitance (328 F g-1 at 0.5 A g-1) and rate capability (75.3% retention at 50 A g-1, and 62.5% retention at 100 A g-1) were observed for this halogenated polymer-derived doped carbon materials (DCM).

Synthesis of Ultrastable Ag Nanoplates/Polyethylenimine-Reduced Graphene Oxide and Its Application as a Versatile Electrochemical Sensor

Investigations on Ag nanostructures/reduced graphene oxide composites have been enormously reported, yet the morphology control of those loaded Ag nanocrystals is still challenging. We herein developed a facile method to grow triagular Ag nanoplates (AgP) on polyetheylenimine-modified reduced graphene oxide (AgP/PEI-rGO). The AgP/PEI-rGO hybrids show unexpected high stability against chloride ion (Cl−) and hydrogen peroxide (H2O2) possibly due to the strong interaction between surface Ag atoms with amine group of PEI. In the chronoamperometry measurements for detecting H2O2, N2H4, and NaNO2, AgP/PEI-rGO hybrids show very wide linear ranges (usually 10-6−10-2 mol·L-1 for H2O2, N2H4, and NaNO2, respectively) and low detection limits down to ~1×10-7 mol·L-1, which demonstrated the promising electrochemical sensor applications of metal/graphene hybrids with well-defined morphologies and facets. Meanwhile, this strategy could be extended to deposition of other noble metals on rGO with controlled morphologies.

Size Control Methods and Size-Dependent Properties of Graphene

Graphene, one of whose lateral sizes is confined to being one atom thick, has grabbed enormous attention ever since the discovery of this atomic thin layer of carbon crystal or polymer which was theoretically proved to be thermodynamically unstable. Size effects of the other two dimensions were then found and investigated. To precisely control the planar size of graphene and chemically convert graphene into nanoribbons or nanoshapes with regularity remains a challengiein this field. A few research groups including ours have pioneered some fundamental work on the size control of this atomic thin carbon layer, which we will summarize and expand in details here in this section. Meanwhile, variations in corresponding properties between different lateral sizes will be depicted. Furthermore, some unsolved problems preventing further progress will be illuminated and possible solutions to them will be given.

Superaerophobic RuO2-Based Nanostructured Electrode for High-Performance Chlorine Evolution Reaction

Single Crystalline Ultrathin Nickel-Cobalt Alloy Nanosheets Array for Direct Hydrazine Fuel Cells

N-doped crumpled graphene: bottom-up synthesis and its superior oxygen reduction performance

The fabrication of crumpled graphene (CrG) was reported applying defluorination of PVDF on highly curved surface of CaC2 particle through bottom-up synthetic strategy. The limited reaction depth between polyvinylidenefluoride (PVDF) and CaC2 lead to the formation of CrG with thin layer (3-6 layer graphene) and reasonable high specific surface area (~324.8 m2 g-1). CrG with N incorporation (N-CrG) was applied as electrode material for reducing oxygen (i.e., oxygen reduction reaction, ORR) in alkaline, showing close onset potential to that of Pt/C and better mass-diffusion behavior. Surprisingly, with increased mass loading of catalysts, N-CrG exhibit steady current increase while Pt/C showed clear current plateau. Meanwhile, high cycling stability and tolerance to contaminant were found for N-CrG sample, demonstrating its high potentials for practical applications. Additionally, the bottom-up synthetic pathway to CrG via polymer dehalogenation on solid alkaline may find more applications which require controlled morphology and thickness of deposited thin graphitic carbon layers.

ZnO-promoted dechlorination for hierarchically nanoporous carbon as superior oxygen reduction electrocatalyst

The dechlorination of polyvinyl dichloride (PVDC) by unconventional agent ZnO at the presence of melamine was used to prepare hierarchically Porous N-Doped nanoCarbon (PDC). ZnO played multirole of dechlorination agent, template for mesopore, and most importantly, ZnCl2 generation source. The latter promoted carbonization and lead to hierarchical micro- and mesopore formation, which facilitated the electric and mass transportation in electrocatalytic oxygen reduction reaction. N-doping was obtained by adding melamine without structure character compromised. The 900 °C-annealed PDC exhibited ultrahigh activity which comprehensively surpassed the commercially available 20 wt.% Pt/C.

One-Step Scalable Production of Co1− x S/Graphene Nanocomposite as High-Performance Bifunctional Electrocatalyst

An alternative pathway to water soluble functionalized graphene from the defluorination of graphite fluoride

In this study, we report a potentially scalable strategy for the cost/ time-efficient production of water-soluble functionalized few layered graphene (FcG) through the mild defluorination of graphite fluoride (GF) at room temperature (RT). The strategy includes mechanical milling which is of high simplicity and operability, and subsequently water purification. By using heteroatom-containing alkaline such as NaNH2 and Na2S, N or S dopants can be functionalized into the defluorinated graphene, leading to the formation of N- and S-doped FcG, respectively. Our methodology of defluorination of GF allows the fabrication of water soluble FcG in much safer ways relative to the conventional Hummers’ method that involves strong acidic/oxidative ambience and disposal of large amount of salt wastes. Meanwhile, the abundance of GF and the simplicity of processibility may also facilitate the practical uses of FcG obtained via our methodology.

Room-temperature synthetic NiFe layered double hydroxide with different anions intercalation as an excellent oxygen evolution catalyst

The Ni–Fe layered double hydroxide (LDH) is regarded one of the best catalysts for the oxygen evolution reaction (OER), yet bridging the relationship between the LDH nanostructure and OER performance still remains a big challenge.

Residual metals present in “metal-free” N-doped carbons

We verified that residual metals were inevitably present in these N-doped carbons and the catalytic performance for the hydrogen evolution reaction (HER) was due to the remaining metals, present at only a ppm level.

Rational design of graphene oxide and its hollow CoO composite for superior oxygen reduction reaction

Graphene oxide (GO) is one important derivative of graphene, fascinating the whole world with its dazzling properties and versatile performance. Yet the chemical routes often show limited control on the density of functionalities and their distribution, forging a barrier in spreading GO’s applications. We modified Hummers’ method and aimed at controlling the oxygen functionality of GO. The modified synthetic GO (MdGO) finds their most oxygen content on edge regions and configuring the overwhelming presence of carboxyl groups which can be easily removed upon annealing. The excellence of high conductivity of intrinsic graphene can be thus recovered after the removal of the main functional groups. Resulted MdGO was reduced and doped by NH3, and reduced MdGO (rMdGO) was tested to be one excellent support for oxygen reduction reaction (ORR) electrocatalyst. As a demonstration, composite of CoO and N-rMdGO was fabricated and exhibiting highly comparable ORR performance in alkaline relative to 20 wt% Pt/C.

A metallic CoS2 nanopyramid array grown on 3D carbon fiber paper as an excellent electrocatalyst for hydrogen evolution

A metallic CoS2 nanopyramid array on 3D carbon fiber paper with ultrahigh HER activity was prepared via solvothermal synthesis.

High-performance aqueous battery with double hierarchical nanoarrays

Promoted Oxygen Reduction Activity of Ag/Reduced Graphene Oxide by Incorporated CoOx

Highly Crystallized Cubic Cattierite CoS 2 for Electrochemically Hydrogen Evolution over Wide pH Range from 0 to 14

Highly Crystallized Cubic Cattierite CoS2 for Electrochemically Hydrogen Evolution over Wide pH Range from 0 to 14

Urchin-like TiO2@C core–shell microspheres: coupled synthesis and lithium-ion battery applications

Carbon coated urchin-like TiO2 microspheres were prepared through coupled hydrolysis of titanium tetrachloride and catalyzed carbonization of glucose.

Green sacrificial template fabrication of hierarchical MoO3 nanostructures

A 3D Nanoporous Ni-Mo Electrocatalyst with Negligible Overpotential for Alkaline Hydrogen Evolution

One-step scalable preparation of N-doped nanoporous carbon as a high-performance electrocatalyst for the oxygen reduction reaction

V2O5 nanostructure arrays: controllable synthesis and performance as cathodes for lithium ion batteries

Hierarchical Ni0.25Co0.75(OH)2 nanoarrays for a high-performance supercapacitor electrode prepared by an in situ conversion process

Preparation of Multi-Metal Oxide Hollow Sphere Using Layered Double Hydroxide Precursors

Extracting genomic DNA of foodstuff by polyamidoamine (PAMAM)–magnetite nanoparticles

One-pot solvothermal method to prepare functionalized Fe3O4 nanoparticles for bioseparation

Surface functionalized magnetic nanoparticles were prepared by a facile one-pot solvothermal method in ethylene glycol solution. Zeta value, size, and magnetic properties could be well tuned by introducing different functional group molecules. Characterizations, including transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), thermo-gravimetric analysis (TGA), X-ray powder diffraction (XRD) and vibrating-sample magnetometer (JSM-13), Fourier Transform Infrared Spectrophotometer (FT-IR) demonstrated the efficiency of this simple and general synthesis strategy. The hydrophilic magnetic nanoparticles with various surface functional groups and zeta values were evidenced an excellent candidate for bioseparation by extracting DNA molecules from a model mixture of cell fractures.

Detection and Isolation of Dendritic Cells Using Lewis X-Functionalized Magnetic Nanoparticles

Understanding the “Tailoring Synthesis” of CdS Nanorods by O2

Parameters such as solution concentrations and composition of the ambient atmosphere are known to be important in phase and morphology control in the solvothermal synthesis of CdS semiconductor nanorods (NRs), but a clear understanding of the underlying mechanisms involved is lacking. In this work, a series of experiments were performed to demonstrate that the key factor affecting the phase and morphology of CdS NRs is the amount of O2 in the space above the reaction solution in the sealed vessel relative to the amount of precursors in solution: O2-depleted or reagent-rich conditions resulted in more cubic phase CdS and thick NRs with an aspect ratio usually less than 3, which have small blue-shifts in band-edge emission and little surface trap emission; while O2-rich or reagent-poor conditions resulted in more hexagonal phase CdS and slim single crystal NRs, which have significantly blue-shifted band-edge emission and relatively strong surface trap emission. Thus increasing the amount of solution in the vessel, changing the ambient atmosphere from air to N2 (Ar), or increasing the reagent concentration all lower the molar ratio of O2 to reagents and lead to more cubic phase and thicker NRs. The results indicate that the composition of the “empty” section of the reaction vessel plays as important a role as the composition of the liquid in determining the phase and morphology, something that has been overlooked in earlier work. A mechanism to explain the effect of oxygen on the nucleation and growth stages has been proposed based on those results and further supported by shaking experiment and ZnS NRs synthesis manipulation. The CdS NRs synthesized under different conditions showed obvious differences in photocatalytic activity, which indicated that controlling the synthetic process can lead to materials with tailored photocatalytic activity.

Evaluation Criteria for Reduced Graphene Oxide