Synthesis from a layered double hydroxide precursor for a highly efficient oxygen evolution reaction

A hybrid of Co3Se4 and FeSe2 prepared via a facile hydrothermal method achieves an efficient OER activity during water splitting.

Hierarchical CoFe-layered double hydroxide and g-C3N4 heterostructures with enhanced bifunctional photo/electrocatalytic activity towards overall water splitting

To achieve sustainable and clean energy for the hydrogen economy, developing efficient earth-abundant and non-noble transition metal photo/electrocatalysts toward overall water splitting is highly desirable. In this work, layered double hydroxide (LDH)@g-C3N4 composites with hierarchical flower-like micro/nanosheets and a high surface area have been synthesized by a solvothermal method. HRTEM images exhibit that the surface of the g-C3N4 nanosheets is highly orientated with the main exposure of the (002) plane. Compared with pristine CoFe-LDH, the hierarchical nanocomposite presents an excellent and stable elecrocatalytic performance in 1.0 M KOH, with a small Tafel slope of 58 mV dec-1 and an overpotential of about 275 mV at a current density of 10 mA cm-2. Simultaneously, CoFe-LDH@g-C3N4 exhibits an exceptional performance for the HER in 1.0 M KOH electrolyte, with an overpotential of 417 mV at a current density of 10 mA cm-2 and a small Tafel slope of 77 mV dec-1. Therefore, this work not only accomplishes improved catalytic activity of CoFe-LDH by the introduction of g-C3N4 nanosheets, but also provides an insight into the correlation between hierarchical flower-like morphologies and photo/electrochemical catalytic activity for overall water splitting

A Cocrystal Precursor Strategy for Carbon-Rich Graphitic Carbon Nitride toward High-Efficiency Photocatalytic Overall Water Splitting

Direct and efficient photocatalytic overall water splitting is crucial for the sustainable conversion and storage of renewable solar energy. Herein, we present the design of a carbon-rich graphitic carbon nitride (Cco-C3N4), prepared from a layered molecular cocrystal precursor. The cocrystal microsheets were synthesized using a facile hydrothermal process. Following two-step thermal treatment and liquid exfoliation, the product maintains the 2D morphology owing to the toptactic transformation process. The Cco-C3N4 exhibits an enhanced photogenerated electron-hole separation, high charge transport capacity, and prolonged lifetime of the carriers, relative to the g-C3N4 system. In the absence of any sacrificial reagent or co-catalyst, the Cco-C3N4 microsheets exhibit a high photocatalytic activity. The work presented in this report supplies a cocrystal route for the orderly molecular self-assembly of precursor materials to tailor the chemical compositions and electronic structures. Moreover, the generation of a highly efficient water-splitting photocatalyst has larger implications for sustainable energy applications.

Amorphous cobalt–iron hydroxides as high-efficiency oxygen-evolution catalysts based on a facile electrospinning process

The first example of amorphous CoFe hydroxide based on the electrospinning process was developed, which was used as an efficient OER catalyst.

Recent developments in stimuli-responsive luminescent films

Luminescent films have attracted a great amount of attention due to their unique properties and various potential applications in optical displays, sensors and switches. Due to the fast development of stimuliresponsive luminescent films, we believe it is timely to introduce recent advances and to promote the trends in this field. In this review, firstly, we describe several effective ways to synthesize stimuliresponsive luminescent films. The attention is then focused on the development of several important fluorescence switching systems, which are sensitive to external stimuli (such as typical physical and chemical environments). Finally, the future trends and perspectives are also briefly discussed.

A three-dimensional nickel–chromium layered double hydroxide micro/nanosheet array as an efficient and stable bifunctional electrocatalyst for overall water splitting

The development of bifunctional and stable non-noble metal electrocatalysts for the high-performance hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is very important and challenging for renewable energy.

Selective formation of luminescent chiral cocrystal: Molecular self-assembly of 2,2′-binaphthol and 2-(3-pyridyl)-1H-benzimidazole

Direct white-light emitting room-temperature-phosphorescence thin films with tunable two-color polarized emission through orientational hydrogen-bonding layer-by-layer assembly

Molecule-based room-temperature-phosphorescence (RTP) materials have received much attention recently. For future optical displays and image applications, the development of ordered RTP thin films is highly important, but the fabrication of such RTP films is much more difficult than that of RTP crystals, and examples are still quite limited. In this work, we confirm that the direct layer-by-layer assembly of a small RTP molecule (DBT) and polyvinyl alcohol (PVA) can be achieved based on hydrogen bonding interaction. The films not only exhibit tunable RTP light-emitting colors upon UV photostimulation at 254 nm and 365 nm, but also exhibit direct white-light-emitting polarized phosphorescence due to the ordered micro/nanostructure of the RTP films. Moreover, the highly enhanced RTP quantum yields and lifetimes upon increasing assembly cycles can be assigned to the strong Fermi coupling between DBT and PVA in the films. It is anticipated that the incorporation of other RTP molecules in flexible polymers based on the ordered LBL assembly can be utilized to fabricate a range of new smart RTP film materials

White-light emission and tunable room temperature phosphorescence of dibenzothiophene

Molecular materials exhibiting room temperature phosphorescence (RTP) have received much attention during last few years. It has been known that different stacking fashions (e.g., formation of polymorph) and aggregation/crystal states could largely influence the RTP efficiency. However, whether the crystal morphology or shape could play a key role in modulation of the RTP has not been detected yet. In this work, we report that the dibenzothiophene (DBT) with the same molecular stacking fashion but different crystal morphologies can present alternated RTP performances. By modulation of the fluorescence and phosphorescence dual emission, a direct warm-white color light-emitting has also been successfully achieved. Moreover, the RTP emission can be further tuned through hybridization with β-cyclodextrin in different ratios, with the longest lifetime of 0.43 s.

Coupling of Bifunctional CoMn-Layered Double Hydroxide@Graphitic C3 N4 Nanohybrids towards Efficient Photoelectrochemical Overall Water Splitting

The development of durable, low-cost, and efficient photo-/electrolysis for the oxygen and hydrogen evolution reactions (OER and HER) is important to fulfill increasing energy requirements. Herein, highly efficient and active photo-/electrochemical catalysts, that is, CoMn-LDH@g-C3N4 hybrids, have been synthesized successfully through a facile in situ co-precipitation method at room temperature. The CoMn-LDH@g-C3N4 composite exhibits an obvious OER electrocatalytic performance with a current density of 40 mAcm-2 at an overpotential of 350 mV for water oxidation, which is 2.5 times higher than pure CoMn-LDH nanosheets. For HER, CoMn-LDH@g-C3N4 (η50=-448 mV) requires a potential close to Pt/C (η50=-416 mV) to reach a current density of 50 mAcm-2. Furthermore, under visible-light irradiation, the photocurrent density of the CoMn-LDH@g-C3N4 composite is 0.227 mAcm-2, which is 2.1 and 3.8 time higher than pristine CoMn-LDH (0.108 mAcm-2) and g-C3N4 (0.061 mAcm-2), respectively. The CoMn-LDH@g-C3N4 composite delivers a current density of 10 mAcm-2 at 1.56 V and 100 mAcm-2 at 1.82 V for the overall water-splitting reaction. Therefore, this work establishes the first example of pure CoMn-LDH and CoMn-LDH@g-C3N4 hybrids as electrochemical and photoelectrochemical water-splitting systems for both OER and HER, which may open a pathway to develop and explore other LDH and g-C3N4 nanosheets as efficient catalysts for renewable energy applications.

Modification of π–π Interaction and Charge Transfer in Ratiometric Cocrystals: Amplified Spontaneous Emission and Near-Infrared Luminescence

Reversible Mechanochromic Delayed Fluorescence in 2D Metal-Organic Micro/Nanosheets: Switching Singlet-Triplet States through Transformation between Exciplex and Excimer

Space-Confined Earth-Abundant Bifunctional Electrocatalyst for High-Efficiency Water Splitting

Vapor-phase π–π molecular recognition: a fast and solvent-free strategy towards the formation of co-crystalline hollow microtube with 1D optical waveguide and up-conversion emission

1D molecular co-crystals with hollow micro-tubular morphology can be fabricated through a facile vapor deposition process, which have potential photonic and photofunctional applications.

Ordered and flexible lanthanide complex thin films showing up-conversion and color-tunable luminescence

Ordered transparent thin films based on alternate layer-by-layer assembly of lanthanide complexes and layered double hydroxide nanosheets have been fabricated, which exhibit up-conversion emission and tunable two-color luminescence.