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The development of efficient water-electrolysis catalysts plays a key role in clean and sustainable energy sources. In this work, 2D FeSe 2 nanoplatelets have been successfully synthesized via a hydrothermal reduction route, which exhibit extraordinarily high catalytic activities and stability for oxygen evolution reaction (OER). The remarkable electrocatalytic performance of FeSe 2 nanoplatelets (e.g., overpotential: 2.2 times higher than that of commercial RuO 2 at 500 mV; Tafel slope: 48.1 mV/dec; steady-state current densities remain constant after 70 h) can be attributed to highly exposed active sites associated with (210) crystal faces; the 2D nanostructure could also facilitate improvement of kinetics of water oxidation. Furthermore, the changes of energy level, band structure and water adsorption ability of FeSe 2 under different bias were further understood based on density functional theory calculation. Therefore, this work provides the first example of FeSe 2 nanoplatelets as OER application, which may open a new avenue to design and explore other Fe-based nanostructures as efficient catalysts for renewable energy. [ABSTRACT FROM AUTHOR]

The construction of new semiconductor photocatalysts toward high-efficiency splitting water has played an important role in developing sustainable and clean hydrogen energy. In this work, new type of micro/nano-sized hybrids were synthesized based on the assembly of 0D Cd 0.5 Zn 0.5 S quantum dots (QDs, size: ca. 5 nm) onto 2D graphitic carbon nitride ( g -C 3 N 4 ) ultrathin microribbons (thickness: ca. 4 nm) via an in-situ growth hydrothermal method. The Cd 0.5 Zn 0.5 S 32 wt%@C 3 N 4 composite exhibits the highest visible-light-driven H 2 -generation rate of 33.41 mmol h −1 g −1 without any noble-metal as cocatalyst, and the apparent quantum efficiency is 46.65% at 450 nm. Such H 2 -generation rate is higher than the pristine g -C 3 N 4 and Cd 0.5 Zn 0.5 S by a factor of 27.39 and 9.18 respectively, which is significantly enhanced compared with most as-reported noble-metal-free semiconductor catalysts to date. In addition, compared with the pristine Cd 0.5 Zn 0.5 S, the photocatalytical stability of Cd 0.5 Zn 0.5 S QDs@C 3 N 4 is highly improved. The enhanced H 2 -generation performance can be attributed to the well-matched energy level and strong electronic coupling between two components at the g- C 3 N 4 interface as well as enhanced visible-light absorption. The uniform dispersion of Cd 0.5 Zn 0.5 S QDs onto the g -C 3 N 4 ultrathin microribbons also facilitates the depression of electron-hole recombination from potential aggregation of Cd 0.5 Zn 0.5 S. Therefore, this work supplies an effective way to obtain promising 2D micro/nanostructures for high-efficiency visible light-induced H 2 -generation. [ABSTRACT FROM AUTHOR]

Luminescent film materials sensitive to pollutions are important to develop new types of optical sensors toward environmental detection. Herein we report organic–inorganic hybrid thin films (TFs) with reversible luminescence response to the volatile nitrobenzene (NB) using layer-by-layer (LBL) assembly of fluorescent brightener CXT and Mg–Al-layered double hydroxide (LDH) nanoparticles. The structural and surface morphology studies show that the TFs are continuous and uniform with stacking order in the normal direction of the substrate. AFM and SEM measurements indicated that the films feature periodic structure with a period of ca. 25 nm as well as uniform surface morphology. Moreover, the CXT/LDH TF displays a high luminescent response as a fast colorimetric chemosensor for NB vapor with a low detection limit (4.02 ppb), good regeneration and high selectivity. In addition, by combining suitable luminescent building blocks, the films can also be extended to other two-color luminescence systems, which exhibit changes in both luminescence intensity and ratiometric fluorescence upon interaction with NB vapor, suggesting that these films can serve as new types of selective solid luminescent sensor. Therefore, this work supplies a facile LBL strategy for the fabrication of TFs as selective luminescent sensor for the trace detection of NB. [ABSTRACT FROM AUTHOR]

Abstract: 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonate) dye (ABTS) and dodecanesulfonate anion (SDS) have been co-intercalated into the ZnAl-layered double hydroxide (ZnAl LDH) matrix by a hydrothermal co-precipitation method, with obtained samples denoted as ABTS–SDS(x)/LDH (x stands for the molar percentage content of ABTS with respect to total intercalated content). The structure and chemical composition of the as-prepared compounds were characterized by X-ray diffraction (XRD), FT-IR spectra and elemental analysis. Fluorescence spectra demonstrated that the sample with 60% ABTS molar percentage, exhibited the optimal luminescent intensity. The fluorescence lifetime of ABTS in the gallery of LDH was enhanced significantly compared with that of pristine ABTS powder. As well, the ABTS–SDS/LDH thin film fabricated by the solvent evaporation method exhibited a well-defined c-orientation, which can be confirmed by XRD and scanning electron microscopy (SEM). Moreover, the ABTS–SDS(60%)/LDH film showed polarized luminescence (anisotropy: 0.35) and electrochemical response to aqueous solution containing Pb2+ ion. These results demonstrate that the ABTS–SDS/LDH system can serve as a good candidate for the solid-sate luminescence and electrochemical sensor materials. [Copyright &y& Elsevier]

Abstract: Optically transparent thin films with photochromic properties have been fabricated by means of co-intercalation of azomethine-H anions (AMH) and 1-pentanesulfonate (PS) with different molar ratios into the galleries of a ZnAl layered double hydroxide (LDH). The photochromism of AMH occurred in a 2D confined inorganic matrix has been studied by steady state and transient UV–vis spectroscopy. The AMH anion undergoes an excited-state intramolecular proton transfer from the enol tautomer to trans-keto tautomer after UV excitation, and the relaxed back-isomerization to the ground state of enol tautomer was investigated by transient UV–vis spectroscopy. [Copyright &y& Elsevier]

Polymorphism has drawn great attention in tuning organic solid-state luminescent materials by alteration of molecular packing structure and has considerable potential application in optoelectronic devices and fluorescence sensors. Herein, two polymorphs based on dicyanodistyrylbenzene (DCS) compound were obtained by solvent induced synthesis. We have comprehensively investigated photophysical properties (such as photoluminescence colors, lifetime and PL quantum yield) of the two polymorphs, blue one αDCFDCS (Aqua) and green one αDCFDCS (Green). The single crystal structure analysis and XRD powder pattern shows that there is a slightly packing dislocation in a-axis account for the difference between the two phases. Mechanical grinding can lead to an alternation in photoluminescence color from blue to green. The differential thermal analysis (DTA) measurement discloses αDCFDCS (Aqua) is the metastable state of the compound. Both of two polymorphs show thermochromic and can be reversibly switched upon heating and cooling, which is attributing to the crystal cell expansion with the temperature increasing revealed by in situ XRD. Moreover, fuming with NH 3 also causes the color change via Lewis acid base reaction. Upon heating or being exposed to HCl, it will return to the original state. The results of the polymorphism not only provide an insight into molecular packing and emission properties, but also pave the way for understanding the solid luminescence change by the multi-stimuli response. Multi-stimuli, color switchable polymorphs based on dicyanodistyrylbenzene (DCS) compound were obtained by solvent induced polymorph synthesis. [Display omitted] • Two polymorphs based on dicyanodistyrylbenzene (DCS) compound were obtained by solvent induced synthesis. • Mechanical grinding of blue phase would change to the green phase. • Thermochromic behaviors and vapochromic photoluminescence behaviors of two polymorphs have been carefully investigated. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) plays a significant role in fertilizer production to support the ever-increasing population and serves as a renewable energy carrier as well as a zero-carbon emission fuel. Currently, NH 3 is produced by a non-sustainable and highly energy-intensive process. Among the available alternatives, the electrochemical nitrogen reduction reactions (NRR) has attracted attention due to the compact and on-site electrolytic cells that can operate from solar or wind power under ambient conditions but still suffer from relatively low Faraday efficiency and NH 3 yields. For the commercialization of electrocatalytic NRR, a catalytic material demonstrating a FE ∼50% and an NH 3 yield rate of ∼10−6 mol s−1 cm−2 is suggested. Various strategies, including amorphization, structural engineering, catalyst-support interactions and hydrogen evolution suppression over catalytic materials, have been presented to enhance the electrocatalytic NRR. In this review, the current progress of various identified NRR electrocatalysts (including metal carbides, nitrides, oxides, phosphides, sulfides, selenides, borides, bimetallic materials, metal-organic frameworks, and metal-free materials) is summarized by collectively focusing on both theoretical analysis and experimental investigations. For further development of rational catalysts, a collaboration of theoretical and experimental studies, advanced characterization techniques, understanding of the electrocatalytic mechanism, efficient screening systems, and precise detection methods are needed. Specially designed electrocatalysts can improve NRR activity by regulating the cathodic reactions. The challenges and future perspectives have been described with special emphasis on various transition metal-based electrocatalysts for N 2 fixation. • Ambient electrochemical ammonia synthesis is an energy-saving approach. • Electrochemical NH 3 synthesis is still in the basic scientific investigation stage. • For NRR commercialization FE ∼50% and an NH 3 yield ∼10−6 mol s−1 cm−2 are advised. • To date, Mo-based compounds have demonstrated high ambient NRR performances. [ABSTRACT FROM AUTHOR]

Although polyphosphazenes having attracted attention for use as flame-retardant coatings for textiles, nonetheless their add-on level is still far from ideal with regard to high-efficiency flame-retardant properties, wearing comfort and durability. Herein, for the first time, a cross-linkable phosphorus and nitrogen-rich polyphosphazene, poly(methoxy/allylphenoxy)phosphazene (PMAP), with mainly methoxy groups and an appropriate amount of unsaturated chemical bonds containing allylphenoxy side groups (ca. 8 %) was synthesized. Subsequently, the noncombustible, transparent, elastic crosslinked PMAP coating was coated on cotton fabrics through dipping and photoinduced cross-linking processes. The PMAP-coated cotton showed high-efficiency flame-retardant properties along with remarkably high durability. The intrinsic properties of cotton fabric, such as whiteness, gas permeability and bending rigidity, were highly reserved after being coated with PMAP. Interestingly, the flame-retardant properties of the 4.9 wt%-coated cotton increased, and the coated cotton obtained a self-extinguishing property and maintained >95 % of its initial mass after 60 rigorous laundry cycles. Moreover, the PMAP-coated cotton exhibited enhanced carbonization ability at lower temperatures, which was the key to the flame-retardant properties of cotton fabric. The PMAP-coated cotton also showed a lower peak heat release rate and total heat release values than the control cotton during combustion. Therefore, the comprehensive highly favorable properties of the PMAP coating make it a cutting-edge material for flame-retardant cotton fabrics and greatly expand its potential in practical applications. • A cross-linkable P-N-rich polyphosphazene elastomer was first applied as a permanent flame retardant for cotton fabrics. • The transparent coating endowed cotton fabrics with remarkable high efficiency of anti-flame properties. • The intrinsic properties of cotton such as whiteness, gas permeability were highly reserved after finishing. • After 60 vigorous laundering cycles, the UV-treated cotton showed unprecedented durability. [ABSTRACT FROM AUTHOR]

Vinyl or styrene-containing ruthenium complexes were previously reported to be reductively electropolymerized, which needed to be carried out under strict deoxygenation conditions. Here, we present the first example of an oxidatively electropolymerized thin film of a styrenyl-containing ruthenium complex, Ru1 under ambient condition. As revealed by UV–visible absorption spectroscopy, emission spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and photoelectrochemical measurements, the electropolymerized films, poly(Ru1) n , exhibited good adherence and chemical stability, porous structure, strong photoluminescence, well reversible and surface-controlled RuIII/II redox behavior. More interestingly, at a -0.4 V external bias potential, a significant cathodic photocurrent density of 8.04 μA/cm2 was observed for poly(Ru1) 3 -modified ITO electrode irradiated by 100 mW•cm−2 white light in an air-equilibrated 0.1 M Na 2 SO 4 aqueous solution. Furthermore, the photo-current polarity could be switched from cathodic to anodic up to a photocurrent density of 9.22 μA/cm2 for poly(Ru1) 3 -modified ITO electrode as the electron donor of quinhydrone was added under external bias potential-free conditions. More interestingly, poly(Ru1) 3 exhibited impressively strong photoelectrochemical oxygen reduction properties with a O 2 -induced 4.7-fold cathodic photo-current enhancement relative to a N 2 -saturated electrolyte solution condition. This work offers an efficient way to fabricate highly stabilized Ru(II) complex-based modified electrodes by facile oxidative electropolymerization of the styrenyl-containing ruthenium complex, offering poly(Ru1) films with intriguing applications in electrochemical, photoluminescence, photoelectrochemical O 2 reduction and solar photoelectric conversion, molecular switching devices. [ABSTRACT FROM AUTHOR]