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Porous carbon encapsulated non-precious metal nanocatalysts have recently opened the ways towards the development of high-performance water remediation and energy conversion technologies. Herein, we report a facile, scalable and green synthetic methodology to fabricate porous carbon encapsulated transition metal nanocatalysts (M@TP: M = Cu, Ni, Fe and Co) using commercial tissue paper. The morphology, crystalline structure, chemical composition and textural properties of the M@TP nanocatalysts were thoroughly characterized. The catalytic activity of the M@TP nanocatalysts was investigated for the degradation of Congo red (CR) via peroxymonosulfate activation. Co@TP-6 was found to be the most active catalyst allowing 97.68% degradation in 30 min with a higher rate constant of 0.109 min−1. The nanocatalysts also displayed a carbon shell thickness-dependent electrocatalytic hydrogen evolution reaction (HER) activity, most likely due to the shielding effect of the carbon layers over the electron transfer (ET) processes at the metal core/carbon interfaces. Remarkably, the Ni@TP-6 electrocatalyst, with the smaller carbon shell thickness, showed the best electrocatalytic performance. They delivered an ultralow onset potential of −30 mV vs RHE, an overpotential of 105 mV at a current density of 10 mA·cm−2 and an excellent electrochemical stability to keep the 92% of the initial current applied after 25000 s, which is comparable with the HER activity of the state-of-the-art Ni-based catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trimetallic NiCoFe PBAs are electrodeposited homogeneously on CFP as precursors. • The NiCoFe-Se NCs grown on CFP as self-supported electrode for OER. • The NiCoFe-Se/CFP exhibits remarkable OER activity and desirable stability. • Trimetallic element regulation effectively improves the OER activity of selenides. The progress of inexpensive, high-efficiency, and steady oxygen evolution reaction (OER) electrocatalysts is of great importance to promoting water splitting for green hydrogen production. Herein, tri-metallic NiCoFe selenide catalyst backed up by carbon fiber paper (CFP) was synthesized by a facile selenization of NiCoFe Prussian blue analogues (PBAs) for OER in alkaline solutions. The NiCoFe-Se/CFP inherited the porous nanostructure of the metal-organic frameworks (MOFs) precursors prepared by rapid cyclic voltammetry electrodeposition. Benefiting from the 3D hierarchical porous structure, optimized electronic structure of NiCoFe selenides and high conductivity, the synthesized electrocatalyst exhibits outstanding catalytic activity to the corresponding mono-metallic or bi-metallic selenides. Specifically, the NiCoFe-Se/CFP electrode demands an overpotential of 221 mV to attain the 10 mA cm−2 current density in 1.0 M KOH solution and a low Tafel slope of 38.6 mV dec-1. The prepared catalyst also displays good stability and durability. These findings prove a feasible strategy to further improve the catalytic activities of non-precious metal based OER electrocatalysts by the cooperation of structure design and chemical component modification. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of 2D Co x Ni y -MOF were synthesized by ultrasonic method. • Ti 3 C 2 T x nanosheets converting the OER process to a reaction-limited one. • 2D Co2NiMOF/MXene were prepared by electrostatically directed assembly. • The MOF/MXene interface allows for the rapid electron and ion transfer. • Benefiting from thin 2D/2D heterostructure, exhibit enhanced OER performance. Hydrogen production from water electrolysis is severely restricted by the poor reaction kinetics of oxygen evolution reaction (OER). In this work, a series of two-dimensional (2D) composites MOF/Ti 3 C 2 T x (the MXene phase) were fabricated by electrostatically directed assembly and used as catalysts for OER. The obtained composite materials exhibit enhanced electrocatalytic properties, thanks to the ultrathin 2D/2D heterostructure with abundant active sites in Co2Ni-MOF and the high electronic conductivity of Ti 3 C 2 T x. Among all the catalysts, Co2Ni-MOF@MX-1 achieved the best oxygen evolution performance with the lowest Tafel slope (51.7 mV dec−1) and the lowest overpotential (265 mV on carbon paper) at the current density of 10 mA cm−2. These results demonstrated that the synthesis of 2D composite materials by electrostatically directed assembly could be a feasible and promising method for the preparation of 2D heterostructure catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Engineering platinum-free catalysts for hydrogen evolution reaction (HER) with high activity and stability is essential for electrochemical hydrogen production. In this paper, we report the synthesis of cobalt-doped AlNi 3 /NiO (Co-AlNi 3 /NiO) electrode with three-dimensional nanoporous structure via chemical dealloying method. Density functional theory (DFT) calculations reveal that Co-AlNi 3 /NiO can accelerate water adsorption / dissociation and optimize adsorption–desorption energies of H* intermediates, thus improving the intrinsic HER activity. Both the introduction of Co and Al can efficiently ameliorate the electronic density around Ni sites of NiO and AlNi 3 , which can effectively reduce the energy barrier towards Volmer–Heyrovsky reaction and thus synergistically promote the hydrogen evolution. Benefiting from the large electrochemical active surface area, high electrical conductivity and electronic effect, the nanoporous Co-AlNi 3 /NiO catalyst exhibits remarkable HER activity with an overpotential of 73 mV at a current density of 10 mA cm−2 in alkaline condition, outperforming most of the reported non-precious metal catalysts. The nanoporous Co-AlNi 3 /NiO catalyst can operate continuously over 1000 h at high current densities with a robust stability. This work provides a new vision for the development of low-cost and efficient electrocatalysts for energy conversion applications. [ABSTRACT FROM AUTHOR]

In this work, Ni and NiFe LDH are coupled on a carbon cloth to synthesize flexible electrocatalysts with superhydrophilic interfaces. DFT calculations demonstrate that the formation of a unique heterostructure induce the redistribution of the surrounding electrons and increase the total density of states near the Fermi energy level, which optimized the Gibbs free energy for hydrogen adsorption. Under alkaline conditions, the HER overpotential is only 36 mv at a current density of 10 mA cm−2, which is fully comparable to noble metal catalysts. [Display omitted] The rational design of morphology and heterogeneous interfaces for non-precious metal electrocatalysts is crucial in electrochemical water decomposition. In this paper, a bifunctional electrocatalyst (Ni/NiFe LDH), which coupling nickel with nickel–iron layer double hydroxide (NiFe LDH), is synthesized on carbon cloth. At current density of 10 mA cm−2, the Ni/NiFe LDH exhibits a low hydrogen evolution reaction (HER) overpotential of only 36 mV due to the accelerated electrolyte penetration, which is caused by superhydrophilic interface. Moreover, an alkaline electrolyzer is formed and provide a current density of 10 mA cm−2 with a voltage of only 1.49 V. It is confirmed by the density functional theory (DFT) that electron from the Ni layer is transferred to NiFe LDH layer, redistributing the local electron density around the heterogeneous phase interface. Thus, the Gibbs free energy for hydrogen adsorption is optimized. This work provides a promising strategy for the rational regulation of electrons at heterogeneous interfaces and the synthesis of flexible electrocatalysts. [ABSTRACT FROM AUTHOR]

Pb SA -Cu/PC with a three-dimensional structure was demonstrated as an efficient CO 2 reduction catalyst to formate. Pb inhibited the formation of COOH*, reduced the energy barrier of rate determining step in the formate formation process, and achieved 97% high formate selectivity. [Display omitted] • Pb SA100 -Cu/CP catalyst is developed by an economical and low-energy method. • The FE formate is 97 % with a partial current density of 27.9 mA cm−2 at − 0.9 V. • The catalyst exhibits ultra-long stability for more than 60 h. • The synergistic action of Pb SA and Cu atoms lowers the RDS for CO 2 RR to fromate. • Single-atom Pb induces Cu charge redistribution and inhibits the formation of COOH*. Exploring highly selective and stable electrocatalysts is of great significance for the electrochemical conversion of CO 2 into fuel. Herein, a three-dimensional (3D) nanostructure catalyst was developed by doping Pb single-atom (Pb SA) in-situ on carbon paper (Pb SA100 -Cu/CP) through a low-energy and economical method. The designed catalyst exhibited abundant active sites and was beneficial to CO 2 adsorption, activation, and subsequent conversion to fuel. Interestingly, Pb SA100 -Cu/CP showed a prominent Faraday efficiency (FE) of 97 % at –0.9 V versus reversible hydrogen electrode (vs. RHE) and a high partial current density of 27.9 mA·cm−2 for formate. Also, the catalyst remained significantly stable for 60 h during the durability test. The reaction mechanism was investigated by density functional theory (DFT), demonstrating that the doping Pb SA induced the electrons redistribution, promoted the formate generation, reduced the rate-determining step (RDS) energy barrier, and inhibited the hydrogen evolution reaction. The study aims to provide a new strategy for developing of single-atom catalysts with high selectivity and stability, which will help reduce environmental pressure and alleviate energy problems. [ABSTRACT FROM AUTHOR]

A novel porous Ni matrix with optimal pore structure and adequate mechanical property is successfully prepared by a modified spark plasma sintering progress, while a self-supporting HER electrode of Ni 3 Se 2 @Porous Ni is subsequently obtained via a facile one-step hydrothermal synthesis. Such the Ni 3 Se 2 @Porous Ni electrode has performed a superior conductivity, excellent catalytic activity and robust durability, which can be attributed to the strong covalent bonding between Ni 3 Se 2 and Ni matrix, abundant active sites of the vertically arranged nanosheets, as well as the metallurgically bonded metal skeleton, exhibiting a fascinating potential for the industrial application. [Display omitted] Developing efficient and durable self-supporting catalytic electrodes is an important way for industrial applications of hydrogen evolution reaction. Currently, commercial nickel foam (NF)-based electrode has been widely used due to its good catalytic performance. However, the NF consisting of smooth skeleton surface and large pores not only exhibits poor conductivity but also provides insufficient space for catalyst decoration and sufficient adhesion, resulting in inadequate catalytic performance and poor durability of NF-based electrodes. In this paper, a novel three-dimensional porous Ni substrate with multangular skeleton surface and small pore structure was prepared by a modified spark plasma sintering technique, and subsequently Ni 3 Se 2 @Porous Ni electrode with a large number of Ni 3 Se 2 nanosheets uniformly distributed on the surface was obtained by one-step in-situ selenization. The electrode exhibits outstanding conductivity and catalytic hydrogen evolution reaction, providing a low overpotential of 183 mV at a current density of 100 mA cm−2. Due to the strong interfacial bonding between Ni and Ni 3 Se 2 , the Ni 3 Se 2 @Porous Ni electrode shows strong durability, which can work stably at 85 mA cm−2 for more than 200 h. This work provides an effective strategy for the rational preparation of metal substrates for efficient and durable self-supporting catalytic electrodes. [ABSTRACT FROM AUTHOR]

We have designed a noble metal-free porous organic polymer (TDA-Trz-POP) having N- and S-rich surface and it showed very low overpotential (129.2 mV w.r.t RHE for 10 mA cm−2 current density) and low Tafel slope (82.1 mV/deg) in the electrochemical water splitting. [Display omitted] Water splitting is a long-standing quest to material research for mitigating the global energy crisis. Despite high efficiency shown by several high cost noble metal containing electrocatalysts in the water splitting reaction, scientists are focused on alternate metal-free carbon or polymer based materials with comparable activity to make the process economical. In this article, we have strategically designed a noble metal-free thiadiazole (TDA) and triazine (Trz) linked porous organic polymer (TDA-Trz-POP) having N- and S-rich surface. Powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR), solid state 13C magic angle spinning nuclear magnetic resonance (MAS-NMR) and X-ray photoelectron spectroscopic (XPS) analyses have been performed to predict its probable framework structure. This scrunch paper type TDA-Trz-POP shows an extravagant potential for the hydrogen evolution reaction (HER) with a low overpotential (129.2 mV w.r.t. RHE for 10 mA cm−2 current density) and low Tafel slope (82.1 mV deg−1). Again, this metal-free catalyst shows oxygen evolution reaction (OER) at 410 mV overpotential w.r.t RHE for 10 mA cm−2 current density with a lower Tafel slope of 104.5 mV deg−1. This bifunctional activity was further tested in two electrodes set-up under different pH conditions. The porosity seems to be a blessing in the electrocatalytic performance of this metal-free electrocatalyst material. Further, the mystery behind the activity of both HER and OER has been resolved through the density functional theory (DFT) analysis. This work provides an insight to the material scientists for low cost, metal-free material design for the efficient water splitting reaction. [ABSTRACT FROM AUTHOR]

Facile synthesis of FeNi alloy-supported N -doped Mo 2 C hollow nanospheres for enhanced oxygen evolution reaction. [Display omitted] • Facile synthesis of FeNi alloy-supported N -doped Mo 2 C hollow nanospheres. • FeNi/Mo 2 C/NC supports strongly accelerated electron transfer, thereby improving the OER kinetics. • FeNi/Mo 2 C/NC hybrids will hold promise in development of electrode materials. The rapid depletion of fossil fuels results in significant environmental pollution. Consequently, researching environmentally friendly and cost-effective electrocatalysts with exceptional oxygen evolution reaction (OER) capabilities holds immense importance in enhancing the efficient utilization of resources. In this paper, a straightforward and cost-effective method was employed to produce Fe-Ni alloy-supported N -doped carbon hollow nanospheres (FeNi/Mo 2 C/NC) using self-assembled molybdenum dopamine spheres (Mo-PDA-HS) as a substrate. The inclusion of iron and nickel addressed the issue of aggregation and collapse in Mo-PDA-HS nanostructures at high temperatures, while adjusting the electronic structure of the composites to achieve efficient OER activity. The composite displayed a low overpotential (η10 mA = 304 mV) and a minimal Tafel slope (41.8 mV/dec-1). This study introduces a simple strategy for constructing structurally robust and non-aggregating Mo 2 C nanostructures, along with a direct method for designing cost-effective and high-performance catalysts for OER. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bifunctional catalyst Fe[ Pc (I) 4 ] + Ni[ Pc (I) 4 ]@NC PDI for ORR and OER is synthesized. • The NC PDI with 2D structure and superior stability was used as support. • Iodine groups in TM[ Pc (I) 4 ] creates a built-in electric field to enhance catalysis. • The synergistic effect of Fe[ Pc (I) 4 ]/Ni[ Pc (I) 4 ] enhances the catalytic performance. • The catalyst has superior performance for ORR/OER in rechargeable Zn-air batteries. In this paper, we report on the preparation and catalysis of a bifunctional molecular catalyst (Fe[ Pc (I) 4 ]+Ni[ Pc (I) 4 ]@NC PDI) for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable Zn-air batteries. This catalyst is prepared by self-assembling tetraiodo metal phthalocyanines (Fe[ Pc (I) 4 ] and Ni[ Pc (I) 4 ]) on a 2D N -doped carbon material (NC PDI) through π-π interactions. The introduction of iodine groups in the edge of phthalocyanines controls the density of electron cloud and electrostatic potential around Fe-N/Ni-N sites and constructs a built-in electric field that facilitates directional transport of charges, enhancing the catalytic activity of the catalyst. Density functional theory (DFT) calculations support this mechanism by showing a reduced energy barrier for the ORR rate-determining step (RDS). The Fe[ Pc (I) 4 ]+Ni[ Pc (I) 4 ]@NC PDI exhibits excellent performance outperforming 20 wt% Pt/C and single-molecule self-assembled Fe[ Pc (I) 4 ]@NC PDI and Ni[ Pc (I) 4 ]@NC PDI , with a half-wave potential of E 1/2 = 0.940 V in the ORR process under alkaline condition. During the OER process, Fe[ Pc (I) 4 ]+Ni[ Pc (I) 4 ]@NC PDI exhibited a low overpotential of 298 mV at 10 mA cm−2 under the alkaline condition, which is much better than RuO 2 , Fe[ Pc (I) 4 ]@NC PDI and Ni[ Pc (I) 4 ]@NC PDI. The catalyst also demonstrates excellent catalysis and durability in rechargeable Zn-air batteries. This work provides a simple and specific method to develop efficient multifunctional molecular electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Designing cost-effective and robust bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly desired in hydrogen production from overall water splitting, but still suffers great challenges due to the sluggish catalytic OER/HER kinetics. In this paper, a surface/defect engineering strategy is developed to synthesize three-dimensional (3D) carbon foam (CF)-supported unique hierarchical Co 3 O 4 nanowires@NiO nanosheets core–shell nanostructured catalyst (NiO@Co 3 O 4 /CF) with rich oxygen-vacancies as a novel bifunctional catalyst for alkaline water splitting electrolysis. Benefited from the synergy of the 3D hierarchical core–shell structure and rich oxygen vacancies, the as-obtained NiO@Co 3 O 4 /CF shows both excellent OER (η 200 = 325 mV, η 500 = 374 mV) and HER (η 10 = 104 mV) activities with low Tafel slopes (64.26 mV dec−1 for OER and 109.14 mV dec−1 for HER, respectively) and outstanding stability. A simple overall water splitting electrolysis cell assembled by this bifunctional NiO@Co 3 O 4 /CF as both OER and HER catalysts requires only a cell voltage of 1.53 V to obtain the current density of 10 mA cm−2 and displays a long-term stability. This work has successfully developed an approach for rational design and novel synthesis of metal oxide hybrids as bifunctional electrocatalysts with high activity and stability for overall water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • A strongly coupled CoP-C/CN photocatalyst is prepared by using amorphous carbon layer as intermediate medium. • A new charge transfer pathway was constructed through VDW forces and P-C bonds. • CoP-C/CN exhibits much enhanced charge transfer and separation efficiency. • CoP-C/CN shows superior activity and stability for photocatalytic H 2 evolution by visible light. Enhancing the charge transmission rate at the interface of transition metal phosphide cocatalysts is an efficient technique to reinforce the photocatalytic activity action of semiconductors, but achieving a faster interface charge transfer rate remains a challenge. This paper reported the coupling of a two-dimensional carbon layer supported CoP (CoP C) as a non-noble metal heterostructure catalyst and a two-dimensional porous graphite carbon nitride (CN) photocatalyst to enhance the transmission rate of photogenerated carriers at the interface. Detailed characterizations and mechanism research have confirmed that the P C bond and Van der Waals heterojunction at the interface function as a novel charge transmission channel, which facilitates the effective transfer of photogenerated carriers from CN to CoP. Furthermore, the large contact area exhibited by the 2D/2D Van der Waals heterojunction offers an increased number of active sites for hydrogen evolution reactions. Consequently, the composite material (CoP C/CN) formed by the coupling of CoP C and CN has an enhanced H 2 production rate of 1503 μmol∙g−1∙h−1 (AQY: 3.03 % at 400 nm) and favorable H 2 production stability under visible light irradiation. This investigation not only provides a new idea for the regulation of interface charge transfer pathway but also offers new inspiration for the photocatalytic system's design with the synergistic impacts of 2D/2D VDW heterojunction and chemical bonds. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Cu dendrites constructed on the surface of copper foam were induced by the potential oscillation generated. • The formation process and morphology control method of copper dendrites are demonstrated. • The geometrical confinement effect induces uniform lithium deposition. • The electrochemical performance of copper foam was significantly improved only by structural modification. Dendrite-free lithium is the ultimate goal in achieving the commercial application of lithium metal anode. In this paper, Dendritic Copper Foam Current Collector (DCFC) is prepared by an electrometallurgy method to realize the homogeneous deposition of lithium metal. The deposition behavior of Cu and Li on different interfaces was studied. Firstly, the Cu dendrites constructed on the surface of Cu foam are induced and formed by the potential oscillation generated by the hydrogen evolution reaction. Secondly, the heterogeneous nucleation model reveals that the reason for the dendrite-free lithium deposition on the dendritic copper foam is the geometrical confinement effect. Compared with commercial copper foam, DCFC with hierarchical structure significantly reduces the nucleation energy and deposition overpotential of lithium metal. The in situ optical microscope observation and finite element simulation results confirm our ideas. Electrochemically, DCFC works stably after 1200 h at a lower potential of 36 mV in a DCFC@Li symmetric battery, which is much superior to 75 mV for just 340 h in Cu foam. The ideal collector with a dendritic structure has broad prospects for the practical application of lithium metal anode. [ABSTRACT FROM AUTHOR]

[Display omitted] The introduction of nitrogen vacancies into polymeric carbon nitride (PCN) has been attested to be a reliable strategy to enhance photocatalytic performance. Nitrogen vacancies were considered as active sites to promote the adsorption of target molecules and capture photoexcited electrons to inhibit the recombination of charge pairs, accelerate photoinduced electrons to participate in photocatalytic reaction. In this paper, a series of PCN with rich nitrogen vacancies were prepared by etching of chromic acid solution. Sample 20KCSCN had the highest photocatalytic performance whose evolution efficiency of CO 2 to CO and CH 4 can reach 3.9 and 0.5 μmol·g−1·h−1, respectively. These evolution efficiencies are 2.9 and 4 times higher than that of the PCN. Meanwhile, 20KCSCN demonstrates high CO conversion selectivity and stability. The successful introduction of nitrogen vacancies not only increases the active sites of PCN surface, but also optimizes the optical structure, which dramatically boosts the separation of photoexcited charge pairs and the reduction capacity of photogenerated electrons. The enhancement mechanism for photocatalytic CO 2 reduction performance of PCN was proposed. Besides, photocatalytic H 2 evolution experiments were performed on all samples to confirm the universality of PCN photocatalytic activity enhancement etched by chromic acid solution. H 2 evolution rate on 20KCSCN can reach 652 μmol·g−1·h−1, which is 1.6-fold higher than that on PCN (254 μmol·g−1·h−1) after 4 h irradiation under a 300 W Xe lamp. This work offers new venue for introducing nitrogen vacancies in PCN to regulate photoexcited charge pairs transfer. The photocatalytic enhancement of CO 2 reduction could be used to alleviate the serious issue of excessive CO 2 emission and energy crisis. [ABSTRACT FROM AUTHOR]

The NiCo-LDH was prepared as a precursor via co-precipitation method and subsequently phosphated into NiCoP nanosheets with a 2D structure. By modifying ZnCdS with 2D NiCoP, the activity of the composite to split water and produce hydrogen under visible light was enhanced. By adjusting the morphology of NiCoP, the recombination of photogenerated carriers is more effectively inhibited, and more catalytic active sites are exposed, which provides a new idea for the preparation of two-dimensional transition metal phosphides. [Display omitted] • A facile approach for synthesizing 2D transition metal phosphide nanosheets is presented. • The ZnCdS photocatalyst decorated by NiCoP nanosheet exhibits 17.3 times higher hydrogen production capacity compared to ZnCdS. • NiCoP accelerates the separation and migration of electron-hole pairs of ZnCdS, Co as the active site can more effectively promote the photocatalytic water splitting reaction. The unique characteristics and diverse applications of 2D transition metal phosphides have aroused significant interest. In this paper, we successfully prepared 2D NiCoP modified ZnCdS composite. The NiCoP nanosheets were successfully obtained by phosphating layered double hydroxide (LDH) precursor. The results show that the ZnCdS-8%NiCoP has the highest photocatalytic performance among all the composite photocatalysts with the H 2 evolution rate of 1370.1 µmol h−1, which is 17.9 folds higher than obtained with pure ZnCdS. Detailed analysis reveal that NiCoP nanosheets functions as an excellent electron acceptor, speeding up the directed migration of electrons. Furthermore, the rational mechanism of photocatalytic has been presented based on density function theory (DFT) calculations, which is well congruent with experimental results. Our research offers a simple, environmentally benign, and scalable technique for making highly effective photocatalysts, as well as a novel perspective on transition metal phosphides rational design. [ABSTRACT FROM AUTHOR]

Hybrid 1T/2H MoS 2 nanosheets with different 1T phase content are vertically grown on conductive carbon cloth and the simulation result shows that the catalytic activity presents a trend of first increasing and then decreasing with the 1T phase content increasing, which agrees well with the experimental results. [Display omitted] Implanting the octahedral phase (1 T) into the hexagonal phase (2H) of the molybdenum disulfide (MoS 2) matrix is considered one of the effective methods to enhance hydrogen evolution reaction (HER) performances of MoS 2. In this paper, hybrid 1 T/2H MoS 2 nanosheets array was successfully grown on conductive carbon cloth (1 T/2H MoS 2 /CC) via facile hydrothermal method and the 1 T phase content in 1 T/2H MoS 2 is regulated to gradually increase from 0 % to 80 %. 1 T/2H MoS 2 /CC with 75 % 1 T phase content exhibits optimal HER performances. The DFT calculation results show that S atoms in 1 T/2H MoS 2 interface exhibit the lowest hydrogen adsorption Gibbs free energies (ΔG H*) compared with other sites. The improvement of HER performances are primarily attributed to activating the in-plane interface regions of the hybrid 1 T/2H MoS 2 nanosheets. Furthermore, the relationship between 1 T MoS 2 content in 1 T/2H MoS 2 and catalytic activity was simulated by a mathematical model, which shows that the catalytic activity presents a trend of increasing and then decreasing with the increase of 1 T phase content. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing efficient and durable bifunctional air–cathode catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the key efforts promoting the practical rechargeable zinc-air batteries (ZABs). In this paper, high-performance bifunctional air–cathode catalysts by a two-step strategy: atomically dispersed Ni on N -doped carbon is first derived from MOF to form uniformly dispersed NiNC, which are pyrolyzed together with Fe source at different high-temperatures to form FeNi@NC-T (T = 800, 900, and 1000 °C) catalysts. The as-synthesized non-noble metal FeNi@NC-900 catalyst exhibits a considerably small potential gap (ΔE) of 0.72 V between ORR and OER, which is as the same as commercial noble metal Pt/C + Ir black mixed catalyst. The performance of the ZABs using FeNi@NC-900 as the air–cathode catalyst displays a power density of 119 mW·cm−2 and a specific capacity of 830.1 mAh·g−1, which is superior to that of Pt/C + Ir black mixed catalyst. This work provides a guideline for designing alloy electrocatalysts with uniform size and nanoparticle distribution for metal-air batteries with bifunctional air-cathodes. [ABSTRACT FROM AUTHOR]

Atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters (Ni 6 NCs) supported on g-C 3 N 4 nanosheets were constructed to enhance the photocatalytic hydrogen evolution performances. [Display omitted] Much effort has been devoted to improving the photocatalytic capacity of graphitic carbon nitride (g-C 3 N 4). In this paper, we reported the successful synthesis of a hybrid photocatalyst with superb photocatalytic hydrogen production activity through decorating atomically precise Ni 6 (SC 2 H 4 Ph) 12 nanoclusters on g-C 3 N 4 nanosheets (labeled as Ni 6 /g-C 3 N 4) at room temperature. Zeta potential experiments demonstrated that the electrostatic interaction between Ni 6 and g-C 3 N 4 led to the formation of Ni 6 /g-C 3 N 4. The photocatalytic measurements revealed that the 5 %-Ni 6 /g-C 3 N 4 prepared with the original mass ratio of m(Ni 6)/m(g-C 3 N 4) = 1/20 exhibited the strongest hydrogen production activity. In the system with triethanolamine (TEOA) as the sacrifice agent, the visible-light hydrogen production rate reached up to 5.87 mmol h−1 g−1, approximately 290 times higher than that of pure g-C 3 N 4 (0.02 mmol h−1 g−1). Density functional theory (DFT) calculations testified that the above significant enhancement of photocatalytic hydrogen evolution of the hybrid photocatalyst arose from the photogenerated electrons transfer from Ni 6 to g-C 3 N 4. [ABSTRACT FROM AUTHOR]

[Display omitted] Efficient, stable and low-cost catalysts are essential for improving the efficiency of hydrogen evolution reactions. Herein, the MoO 2 @Ni 2 P heterostructure electrocatalyst was synthesized in a self-supported system on a carbon paper (CP) by two-step deposition and phosphorization at low temperature. The self-supported nanoarray structure makes the catalyst to effectively and efficiently transfer electrons and exposes more of its active sites. Moreover, the strong interaction between Ni 2 P and MoO 2 helps to effectively optimize the electronic structure. The density of states calculations demonstrate that there is an increase in the density of electronic states near the MoO 2 /Ni 2 P Fermi level. This shows that MoO 2 /Ni 2 P has fast charge transfer kinetics. MoO 2 modulates the d-band center of nickel, resulting in moderate adsorption/desorption of hydrogen. The above results show that MoO 2 @Ni 2 P has good hydrogen evolution activity. The experimental results show that the overpotential (η 10) of MoO 2 @Ni 2 P/CP in the alkaline environment is only 57 mV with a Tafel slope of 61 mV dec−1. It is similar to the commercial noble-metal catalysts and outperforms most reported catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of low-cost electrocatalysts with high oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance is crucial for devices used to convert and store hydrogen energy. Research on OER and ORR catalysts has attracted a lot of attention. The limited single-functional catalysts can be expanded as bi-functional catalysts to meet the extra requirement of preparing high-performance catalysts. In this study, we prepared Co-ZIF/CNF in which carbon nanofibers uniformly encapsulated Co– nanoparticles by electrospinning and simple pyrolysis. Co-ZIF/CNF contains both CoO x and Co-N y active sites, showing bifunctional activity for OER and ORR. The optimized catalyst Co-ZIF 1.5 /10CNF 2 has a low OER overpotential of 390 mV, an onset potential of 0.93 V and a half-wave potential of 0.85 V of ORR, exhibiting an outstanding OER and ORR catalytic performance. The catalyst retained 87.53 % of its current after 12 h, showing great stability. This paper provides a new strategy for designing and preparing OER and ORR bifunctional catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Efficient, stable and low-cost catalysts are essential for improving the efficiency of hydrogen evolution reactions. Herein, the MoO 2 @Ni 2 P heterostructure electrocatalyst was synthesized in a self-supported system on a carbon paper (CP) by two-step deposition and phosphorization at low temperature. The self-supported nanoarray structure makes the catalyst to effectively and efficiently transfer electrons and exposes more of its active sites. Moreover, the strong interaction between Ni 2 P and MoO 2 helps to effectively optimize the electronic structure. The density of states calculations demonstrate that there is an increase in the density of electronic states near the MoO 2 /Ni 2 P Fermi level. This shows that MoO 2 /Ni 2 P has fast charge transfer kinetics. MoO 2 modulates the d-band center of nickel, resulting in moderate adsorption/desorption of hydrogen. The above results show that MoO 2 @Ni 2 P has good hydrogen evolution activity. The experimental results show that the overpotential (η 10) of MoO 2 @Ni 2 P/CP in the alkaline environment is only 57 mV with a Tafel slope of 61 mV dec−1. It is similar to the commercial noble-metal catalysts and outperforms most reported catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of low-cost electrocatalysts with high oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance is crucial for devices used to convert and store hydrogen energy. Research on OER and ORR catalysts has attracted a lot of attention. The limited single-functional catalysts can be expanded as bi-functional catalysts to meet the extra requirement of preparing high-performance catalysts. In this study, we prepared Co-ZIF/CNF in which carbon nanofibers uniformly encapsulated Co– nanoparticles by electrospinning and simple pyrolysis. Co-ZIF/CNF contains both CoO x and Co-N y active sites, showing bifunctional activity for OER and ORR. The optimized catalyst Co-ZIF 1.5 /10CNF 2 has a low OER overpotential of 390 mV, an onset potential of 0.93 V and a half-wave potential of 0.85 V of ORR, exhibiting an outstanding OER and ORR catalytic performance. The catalyst retained 87.53 % of its current after 12 h, showing great stability. This paper provides a new strategy for designing and preparing OER and ORR bifunctional catalysts. [ABSTRACT FROM AUTHOR]

A novel 2D/0D hybrid photocatalyst composed of porous Co x P nanosheets and Mn 0.35 Cd 0.65 S nanoparticles has been developed, and presents efficient photocatalytic H 2 evolution from water splitting. [Display omitted] • Porous Co x P nanosheets were prepared by phosphating Co(OH) 2 nanosheets. • 2D/0D Co x P/Mn 0.35 Cd 0.65 S were fabricated using a simple solution-phase method. • Co x P/Mn 0.35 Cd 0.65 S exhibited dramatically enhanced photoactivity for H 2 generation. • The behavior of photoexcited charge carriers in Co x P/Mn 0.35 Cd 0.65 S were investigated. Incorporating 2D transition-metal phosphides into visible-light-driven semiconductors is fascinating for advancing novel photocatalysts. In this paper, porous Co x P nanosheets prepared by phosphating Co(OH) 2 nanosheets are coupled with Mn 0.35 Cd 0.65 S nanoparticles for significantly boosted photocatalytic H 2 evolution performance. The optimal Co x P/Mn 0.35 Cd 0.65 S hybrids show an excellent visible-light H 2 production rate of 7188.9 μmol g−1h−1 upon visible light with an apparent quantum yield (AQY) of 18.9% at 420 nm. The H 2 production rate of the 5% Co x P/Mn 0.35 Cd 0.65 S sample is about 257 times bare CdS and even 18 times higher than pristine Mn 0.35 Cd 0.65 S. This dramatic photocatalytic H 2 generation activity is mainly ascribed to the efficient charge transfer and abundant active sites by introducing the porous Co x P nanosheets. The photocatalytic mechanism of the Co x P/Mn 0.35 Cd 0.65 S composites is investigated by the photoluminescence (PL), time-resolved photoluminescence (TRPL), electrochemical, and photoelectrochemical (PEC) tests. This work presents a viable strategy to design a 2D/0D hybrid system containing porous cobalt phosphides nanosheets and MnCdS solid solutions for noble-metal-free photocatalytic application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Designing MnO functionalized Fe 3 C@nitrogen doped mesoporous Fe x Mn y @NC materials. • Mn boosts the formation of mesoporous structures along surfaces of Fe x Mn y @NC. • The HER E onset and E 10 values of Fe 3 Mn 1 @NC just 84.8 and 156 mV more negative than Pt/C. • The OER E onset and E 10 values of Fe 3 Mn 1 @NC just 8 and 18.7 mV more positive than RuO 2. • A low voltage of 1.6287 V at 10 mA cm−2 for Fe 3 Mn 1 @NC||Fe 3 Mn 1 @NC just 24.9 mV larger than 1.6038 V of Pt/C||RuO 2. In the development of water splitting, the sluggish electrocatalytic kinetics of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have restricted their energy conversion efficiencies. Along with the continuous rise in the prices of noble metals and transition metals (such as cobalt and nickel), constructing high-efficiency HER/OER catalysts based on low cost transition metals, such as iron and manganese, is becoming more meaningful in developing industrialized water splitting devices. In this paper, in the absence of a template or active agent, three-dimensional, hierarchically porous Fe x Mn y nanoparticles (NPs) were embedded and nitrogen-doped carbon materials (denoted as Fe x Mn y @NC; x:y, representing the molar ratio of Fe:Mn) were successfully prepared via pyrolysis of corresponding precursors containing different metallic salt components. Various morphological, structural, and chemical characterization analysis demonstrate that at an Fe:Mn molar ratio of 3:1, the optimal Fe 3 Mn 1 @NC material shows high graphitization degree, rich mesoporous structures, a large surface area, and abundant carbon defects/edges, which promote the uniform dispersion of pyridinic-N (pyridinic- N -metal), graphitic-N, carbon oxygen bonds (C O), manganese oxide (MnO) nanocrystals, and Fe 3 C NPs-embedded, N -doped carbon sheet (Fe 3 C@NC) active sites. In alkaline conditions, the HER onset potentials (E onset) and potentials recorded at 10 mA cm−2 (E 10) of the optimal Fe 3 Mn 1 @NC are just 84.8 and 156 mV more negative than those of 20 wt% platinum carbon (Pt/C). Meanwhile, the OER E onset and E 10 values of the optimal Fe 3 Mn 1 @NC are just 8 and 18.7 mV more positive than those of RuO 2. Furthermore, optimized Fe 3 Mn 1 @NC catalysts were assembled into a water splitting cell, where the catalytic current density achieves 10 mA cm−2 at a low voltage of 1.6287 V (with superior catalytic stability), which is just 24.9 mV higher than that of the (-) 20 wt% Pt/C||RuO 2 (+) benchmark (1.6038 V) under the same conditions. This work describes the regulating efficiency of Mn toward growing mesopores and opens new possibilities for the development of novel carbonaceous catalysts with excellent hydroxide catalytic efficiencies based on low cost Mn/Fe elements. [ABSTRACT FROM AUTHOR]

Schematic diagram of fabricating process of NixSey/MoSe2/NF hollow rod arrays. [Display omitted] Alkaline water electrocatalysis is considered as one of the most reliable method to prepare the stable, inexpensive, and sustainable water splitting catalyst in large-scale. Recently, MoSe 2 attracted great attention as a promising catalyst because of its high electrochemical activity and earth-abundant nature. In this paper, bionic Ni x Se y /MoSe 2 coralline-liked heterogeneous structures were successfully prepared on 3D nickel foam (NF) via a simple solvothermal process complemented by hydrothermal strategy with selenization and alkali treatment. Furthermore, to overcome the less active sites and poor electrical conductivity of MoSe 2 , we learned from the coral structure for the inspiration, and reported a novel hollow rod-like structure with increased active sites. Also, 1 T-2H MoSe 2 improved the electrical conductivity of single phase MoSe 2. We first confirmed the multi-phase of catalyst by XPS analysis with Mo 3d 5/2 splited into two independent regions with the 2H and 1 T phase transition. The optimal ratio of Ni x Se y/ MoSe 2 /NF-5 exhibited excellent electrocatalytic activity towards HER in 1 M KOH, driving current densities of 10, 100 and 200 mA cm−2 at only 76, 165 and 194 mV with stability over 24 h. The work provides new ideas for the construction of transition metal selenides hollow rod array structures of efficient HER electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] As a promising dopant, electron deficient B atom not only tunes the electronic structure of electrocatalysts for improving their intrinsic catalytic activities, but also combines with hydroxy radical as strong adsorption sites for accelerating the water dissociation during the hydrogen evolution reaction (HER). In this paper, we report an electrocatalyst based on boron-modified Ru anchored on carbon nanotubes (B-Ru@CNT) that shows impressive HER activity in acidic and alkaline media. The boron-rich closo -[B 12 H 12 ]2- borane was selected as a moderately strong reductant for the in situ reduction of a Ru salt, which yielded B-doped Ru nanoparticles. The experimental and theoretical results indicate that the incorporation of B not only weakens the Ru-H bond and downshifts the d-bond centre of Ru from the Fermi level by reducing the electron density at Ru but also accelerates the water dissociation reaction by providing B sites, which strongly adsorb OH* intermediates, and nearby Ru sites, which act as sites for the adsorption of the H* intermediate, thus boosting the HER performance and enhancing the HER kinetics. As a result of the tuning of the electronic structure via B doping, B-Ru@CNT showed excellent HER performance, yielding overpotentials of 17 and 62 mV at a current density of 10 mA cm−2 in alkaline and acidic solutions, respectively. These results indicate that our synthetic method is a promising route to B-doped metallic Ru with enhanced pH-independent HER performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • WN nanosheets were prepared by sol–gel method. • CdS/WN was prepared by one pot solvothermal method. • Intimate interfacial contact between CdS NPs and WN engenders Schottk junction. • The evolution rate of optimal CdS/WN H 2 was 9.28 times that of CdS NPS. Based on the strategy that electrocatalysts can be used as additives to improve the performance of photocatalysts, and the unique metalloid properties of tungsten nitride (WN), it can form a Schottky junction with the semiconductor at the heterogeneous interface to improve the photocatalytic performance of semiconductor catalysts. In this paper, WN with excellent electrical conductivity was selected as a new noble-metal-free co-catalyst to improve the photoreduction hydrogen (H 2) evolution performance of CdS nanoparticles (NPs). Firstly, WN nanosheets were prepared by sol–gel method; then, a novel and noble-metal-free heterojunction photocatalyst, which is CdS NPs deposited on the surface of WN, was successfully fabricated via one-pot solvothermal method. Under visible light irradiation, the H 2 production rate of the WN/CdS composite catalyst is 24.13 mmol/g/h, which is 9.28 times that of pure CdS NPs. The observably boosted H 2 generation activity could be ascribed to the broadened visible-light absorption and intimate interfacial contact between CdS NPs and WN engenders Schottky junction. This study provides a novel and cost-effective approach for designing efficient noble-metal-free photocatalysts and improving H 2 evolution activity of CdS under visible-light-driven photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

Sovolthermally synthesized Co-MOFs exhibits high activity and stability for water oxidation. [Display omitted] The development of efficient and robust non-precious electrocatalysts for water oxidation at a mild condition is extremely desirable for industrial water splitting. Herein we developed a facile solvothermal strategy to synthesize cobalt metal organic frameworks (Co-MOFs) with sheet-like structure, which showed highly promising performance for electrocatalytic oxygen evolution. The best Co-MOF sample afforded an ultra-high oxygen evolution current density of 63.4 mA cm−2 at 1.75 V in 1 M KOH with a catalyst loading of only 0.21 mg cm−2. Notably, its electrochemical performance remained unchanged after 10,000 cyclic voltammograms indicating very promising long-term stability. Detailed study of the mechanism of the oxygen evolution by density functional theory (DFT) indicated that the strong π-conjugation formed between the central cobalt ion and adjacent aromatic rings favored the high electrocatalytic performance. The solvothermally synthesized MOFs proposed in this paper are expected to inspire the rational design of high-performance electrocatalysts for water oxidation with atomic and molecular level structural control and the exploration of structure-performance relationships to understand the electrocatalytic origin. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystalline Ni(OH) 2 /Amorphous NiMoS electrocatalyst were designed and synthesized by two-step hydrothermal process. • The as-obtained material shows excellent hydrogen evolution over all pH ranges. • The synergistic mechanism and the role of crystalline Ni(OH) 2 and amorphous NiMoS was elucidated. Designing and fabricating efficient electrocatalysts is a practical step toward the commercial application of the efficient hydrogen evolution reaction (HER) over all pH ranges. Herein, novel Ti@Ni(OH) 2 -NiMoS heterostructure with interface between crystalline Ni(OH) 2 and amorphous NiMoS was rationally designed and fabricated on Ti mesh (denoted as Ti@Ni(OH) 2 -NiMoS). Acid etching and calcination experiments helped in accurate elucidation of the synergistic mechanism as well as the vital role on crystalline Ni(OH) 2 and amorphous NiMoS. In acidic solutions, the HER performance of Ti@Ni(OH) 2 -NiMoS was mainly attributed to the amorphous NiMoS. In neutral, alkaline, and natural seawater solutions, the HER performance was mainly determined by the synergistic interface behaviors between the Ni(OH) 2 and NiMoS. The crystalline Ni(OH) 2 accelerated water dissociation kinetics, while the amorphous NiMoS provided abundant active sites and allowed for fast electron transfer rates. To deliver current densities of 10 mA·cm−2 in acidic, neutral, alkaline, and natural seawater solutions, the Ti@Ni(OH) 2 -NiMoS required overpotentials of 138, 198, 180 and 371 mV, respectively. This paper provides general guidelines for designing efficient electrocatalyst with crystalline/amorphous interfaces for efficient hydrogen evolution over all-pH ranges. [ABSTRACT FROM AUTHOR]

The lamellar Ni-MOF-74 are used to modify the Mn 0.2 Cd 0.8 S for the first time through a reasonable and handy design. Mn 0.2 Cd 0.8 S nanorods are uniformly dispersed on the surface of Ni-MOF-74, and the matching of morphology reduces the aggregation of the original Mn 0.2 Cd 0.8 S nanorods and improves the response ability of the composite catalyst to visible light. A special electrons transfer channel (Ni-S bond) between lamellar Ni-MOF-74 and Mn 0.2 Cd 0.8 S nanorods is constructed in this paper compared with previous similar work [26], which greatly accelerates the directional transfer of photo-generated carriers from Mn 0.2 Cd 0.8 S to Ni-MOF-74. The characterization results show that the composite catalyst has the longest carrier lifetime, the fastest charge transfer rate and the lowest hydrogen evolution overpotential by comparing with the Ni-MOF-74 and Mn 0.2 Cd 0.8 S. [Display omitted] The morphology modification and the construction of heterojunction of the photocatalyst are considered as the main means to significantly improve the performance of photocatalytic hydrogen evolution. In this study, Mn 0.2 Cd 0.8 S nanorods are successfully assembled on the surface of Ni-MOF-74 with flake morphology. Specifically, the Ni-S bond is constructed between Ni-MOF-74 and Mn 0.2 Cd 0.8 S, which provides a unique transfer channel for photo-induced carriers. Meanwhile, the electrons in the conduction band of Mn 0.2 Cd 0.8 S can be injected into the conduction band of Ni-MOF-74 quickly due to the potential energy difference between the two. This shows that the recombination of photogenerated carriers in Mn 0.2 Cd 0.8 S can be greatly inhibited. Fluorescence spectroscopy and electrochemical characterization reveal that the composite catalyst has the longest carrier lifetime, the fastest charge transfer rate and the lowest overpotential compared with the Mn 0.2 Cd 0.8 S and Ni-MOF-74. The optimal hydrogen production rate of the composite can reach 7.104 mmol g−1h−1, which is 6.96 times that of Mn 0.2 Cd 0.8 S. This work provides a novel strategy for the modification of MnCdS-based photocatalysts by metal–organic framework materials. [ABSTRACT FROM AUTHOR]

The energy level diagram for electronic transfer vs. Vacuum level; (B and C) The photocatalytic mechanism over EY-sensitized UiO-66/WP. The abundant transition metal phosphides co-catalysts on the earth can satisfy the sustainable and clean solar H 2 production through photocatalytic water splitting, which is promising to replace the rare precious metals, such as Pt, Au, Pd, Ru and so on. In this paper, we use the temperature-programmed solid phase method to prepare WP nanoparticles. Based on the Density Functional Theory (DFT) calculations, we demonstrate that the WP nanoparticles possess outstanding electrical conductivity and excellent capability to transport electrons. WP nanoparticles are loaded onto the surface of UiO-66 via the ultrasound-assisted impregnation method to induce a highly efficient visible-light photocatalytic H 2 production activity of 384 µmol in 5 h, which is 10.67 times than that of pure UiO-66. The catalytic performance is attributed to the excellent metallic conductivity and the favourable Fermi level position of WP nanoparticles. Further studies of PL, TRPL and Mott-Schottky curves, we can not only know that the modification of WP nanoparticles do improve the electron transfer ability, but also that the matched work functions between the EY and UiO-66 provides a feasible thermodynamic path for the transmission of electrons. Our work demonstrates that the earth-abundant transition metal phosphides material have the potential to construct cheaper and high catalytic performance photocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical hydrogen evolution reaction (HER) from water splitting is a promising way to promote the utilization of renewable energy. Designing and fabricating electrocatalysts with low cost, high catalytic activity and robust stability is desirable. In response, we prepared carbon shells encapsulating ultrafine β-Mo 2 C nanoparticles with N and P dual-doping as advanced electrocatalyst used for HER in both acidic and alkaline mediums. This paper gives a discussion on element doping and porosity which have influence on the HER performance. As introducing heteroatoms into carbon matrix to create active sites and enhance electron transfer capacity, the as-prepared electrocatalyst exhibits high catalytic activity with low overpotential of 117 mV and 121 mV to achieve current density of 10 mA cm−2 in acidic and alkaline solutions. Due to the strategy of carbon shells encapsulating, the catalyst presents robust stability for a long time at various applied potential. Furthermore, the design idea of using multiple strategies preparing catalysts may serve some inspiration to fabricate advanced electrocatalysts. [ABSTRACT FROM AUTHOR]

Graphical abstract Three-dimensional hierarchically meso-macroporous carbon nanosheets with vast alloy nanoparticles embedding (denoted as Fe 3 Co 7 @PCNSs) were successfully synthesized and acted as high-efficiency water splitting catalyst. Abstract Developing high-efficiency catalysis electrodes towards both HER (hydrogen evolution reaction) and OER (oxygen evolution reaction) is critical to the popularity and practical application of devices for conversion and storage of clean and renewable hydrogen energy by overall water splitting. In this paper, a series of transition metal alloy nanoparticles embedded hierarchically porous carbon nanosheets (denoted as Fe x Co y @PCNSs) have been successfully designed and synthesized. After optimizing the metallic contents in Fe x Co y alloy, Fe 3 Co 7 @PCNSs displays superior water electrolysis performances compared to other control samples and previously reported non-noble metal catalysts. This advance is mainly due to the synergistic effect of increased carbon edges exposure, abundant accessible active sites, and improved electron/mass transport capability of 3D hierarchically porous architecture. More importantly, when Fe 3 Co 7 @PCNSs is applied as both cathode and anode in a two-electrode cell for carrying out the overall water splitting process, it just needs the corresponding cell voltages of 1.667 and 1.707 V to attain the 10 and 20 mA cm−2 current densities respectively. The synthesis of Fe 3 Co 7 @PCNSs confirms the importance of Fe and Co elements in designing catalyst structures. The electrochemical measurements further display the key roles of structural features and metal alloy@C active sites for boosting water splitting performances. [ABSTRACT FROM AUTHOR]

The intriguing features of two-dimensional (2D) materials such as better charge carrier separation and abundant surface reaction sites endow them with potential applications as cocatalysts in photocatalysis. In this paper, a ternary 2D nickel hydroxide/sulfides nanosheet composed of Ni(OH) 2 , Ni 3 S 2 and Ni x S 6 was loaded on CdS nanospheres by a simple chemical deposition route. The composition of nickel hydroxide/sulfides was determined clearly through an overall analysis using X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Mott-Schottky, electrochemical impedance, steady-state and time-resolved photoluminescence spectroscopy were used to investigate the charge transfer process in CdS and Ni(OH) 2 /Ni 3 S 2 /Ni x S 6 -CdS. The results confirm that a synergistic effect of Ni(OH) 2 /Ni 3 S 2 /Ni x S 6 on CdS has occurred under light irradiation, where the Ni(OH) 2 and nickel sulfides act as hole storage and surface reaction sites, respectively, to promote the charge transfer on CdS. The improved charge transfer and separation efficiency as well as the increased surface reaction sites in Ni(OH) 2 /Ni 3 S 2 /Ni x S 6 -CdS finally result in a dramatically improved photocatalytic performance. The photocatalytic H 2 evolution rate of Ni(OH) 2 /Ni 3 S 2 /Ni x S 6 -CdS is ca . 46 times higher than that of CdS, and the photocatalytic stability of CdS is also improved substantially under visible light irradiation. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (CN) is considered as a promising photocatalyst for solar energy conversion. However, low specific surface area and fast electrons and holes recombination restrict the photocatalytic applications of CN material. Herein, a nitrogen defect-rich and highly porous CN nanostructure (CN-LT) was prepared by combining two strategies, i.e., LiOH treatment and heat etching. The as-prepared nitrogen defect-rich porous CN-LT not only has a larger specific surface area, as compared with pristine CN, but also the photogenerated electron-hole separation was boosted remarkably. Using Pt as a co-catalyst and lactic acid aqueous solutions as sacrificial reagent under visible light irradiation (λ > 400 nm), the hydrogen evolution reaction (HER) rate for CN-LT (1.54 mmol h−1 g−1) was 19.25 times higher than that for pristine CN (0.08 mmol h−1 g−1). While subjecting pristine CN to heat etching under the same experimental conditions, excepting the use of LiOH (CN-T), an increase in HER rate of 7.5 times was obtained. Our current study may shed more light on the enhancement of the photocatalytic activity of bulk CN materials by altering their microstructure. [ABSTRACT FROM AUTHOR]