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The lateral size of graphene nanosheets plays a critical role in the properties and microstructure of 3D graphene as well as their application as supports of electrocatalysts for CO2 reduction reactions (CRRs). Here, graphene oxide (GO) nanosheets with different lateral sizes (1.5, 5, and 14 µm) were utilized as building blocks for 3D graphene aerogel (GA) to research the size effects of GO on the CRR performances of 3D Au/GA catalysts. It was found that GO-L (14 µm) led to the formation of GA with large pores and a low surface area and that GO-S (1.5 µm) induced the formation of GA with a thicker wall and isolated pores, which were not conducive to the mass transfer of CO2 or its interaction with catalysts. Au/GA constructed with a suitable-sized GO (5 µm) exhibited a hierarchical porous network and the highest surface area and conductivity. As a result, Au/GA-M exhibited the highest Faradaic efficiency (FE) of CO (FECO = 81%) and CO/H2 ratio at −0.82 V (vs. a Reversible Hydrogen Electrode (RHE)). This study indicates that for 3D GA-supported catalysts, there is a balance between the improvement of conductivity, the adsorption capacity of CO2, and the inhibition of the hydrogen evolution reaction (HER) during the CRR, which is related to the lateral size of GO. [ABSTRACT FROM AUTHOR]

Hydrogen energy is considered as promising renewable resource and desirable alternative to fossil fuels for future energy supply. Hydrogen production from electrocatalytic water splitting is a green and key approach for hydrogen energy development and application, and the effective electrocatalysts for hydrogen evolution reaction (HER) with low cost is the focus of ongoing research. Currently, noble metals‐based materials are the most effective and durable electrocatalysts for HER, while the high cost and low reserves greatly hinder their commercial applications. Recently, layered double hydroxides (LDHs) with interesting properties, such as the tunability of metal cation and interlayer anions, the adjustability of the thickness and spacing for the layers, low cost, and memory effect, have emerged as excellent electrocatalysts to enhance HER performance. Herein, the principal mechanisms and some key parameters for HER are firstly briefly introduced. Afterwards, the structural features and characteristics of LDHs are provided, and the typical design strategies to improve the HER activity of binary and ternary LDHs‐based catalysts are analyzed and discussed. In addition, the relationship between the morphology, structure, composition and involved electronic effects are focused and emphasized. Finally, the challenges and prospects of LDHs‐based catalysts for enhanced HER performance are proposed. [ABSTRACT FROM AUTHOR]

In this research, cast magnesium alloys AZ31-xGd are assessed as anode material candidates for primary Mg-air batteries. The effects of Gd content in the microstructure, discharge behavior and electrochemical properties of cast AZ31 as an anode are studied through microstructure characterization, electrochemical measurements and battery discharge tests. Results indicate that the introduction of Gd can refine α-Mg grains. The discharge and electrochemical properties of magnesium alloys are improved by optimizing its composition. We confirm that the Al2Gd can restrain the kinetics of hydrogen evolution reaction. The acicular structure can connect the magnesium alloy matrix and reduce the chunk spalling. The data suggest that AZ31-5.8Gd alloy has the best self-corrosion resistance performance and discharge behavior among all prepared AZ31-xGd alloys. AZ31-5.8Gd can output a high specific capacity of 1411.8 mAh g−1 and a high energy density of 1153 mWh g−1 at the current density of 40 mA cm−2. The anode efficiency can reach up to 63.21%. The addition of Gd properly can optimize magnesium alloy microstructure and improve the discharge performance. [ABSTRACT FROM AUTHOR]

Large‐scale hydrogen production through electrocatalytic water splitting holds great promise to alleviate the energy crisis and environmental issue. For cathodic hydrogen evolution reaction (HER), developing efficient and low‐cost electrocatalysts is highly desired to accelerate the reactive process and reduce energy consumption. In past few years, ruthenium and ruthenium‐based compounds electrocatalysts emerge as alternatives for the benchmark platinum for HER. Herein, the recent advances for the preparation of ruthenium‐based electrocatalysts towards HER is summarized, then we also discuss the prospect and challenge for the development of effective electrocatalysts based on ruthenium. [ABSTRACT FROM AUTHOR]

Li–S battery is considered as one of the most competitive energy storage devices mainly due to the high theoretical specific capacity and high specific energy. However, when facing with the practical application, some issues, especially poor electro-conductivity of element sulfur and severe polysulfides (LiPSs) migration, are still needed to solve to further improve the performance of the Li–S batteries. Aiming at the above two disadvantages, in this work, multifunctional separators are designed as efficient LiPSs absorber via coating vapor grown carbon fiber/MoS 2 (VGCF/MoS 2) composites on the polypropylene separator (PP) near the cathode side. For the as-prepared VGCF/MoS 2 coated polypropylene separator (VM/PP), MoS 2 could provide strong chemical adsorption for the LiPSs, while the VGCF framework could act as an electronic transmission channel for the conversion of LiPSs, and also provide physical adsorption for LiPSs at the same time. Benefit from these characteristics, the batteries with VM/PP exhibits a high initial capacity of 1208.7 mAh g−1 at 0.2C and maintains at 862.4 mAh g−1 after 200 cycles. Impressively, the VM/PP shows the high specific capacity of 904.3 mAh g−1 and long-lasting cycling stability with 0.03% capacity attenuation per cycle over 600 cycles at 1.0C, demonstrating excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Vertically aligned two-dimensional ReSe 2 are directly grown on conductive substrates by a chemical vapor deposition method for enhanced electrocatalytic hydrogen production. Two-dimensional electrocatalysts with high-density active sites together with a good charge transfer to the conductive substrates can improve their hydrogen evolution reaction performances. Typically, a good contact between catalyst and electrode to enhance charge transfer can be achieved by way of direct growth. However, a controllable growth of vertically aligned two-dimensional ReSe 2 directly on conductive substrates as working electrodes is not reported. In this work, for the first time, vertically aligned ReSe 2 nanosheets directly on conductive substrates (carbon cloth and glass carbon) are realized though a controllable chemical vapor deposition method. Compare to the way of transferring two-dimension ReSe 2 , the electrode with optimized growth of two-dimensional ReSe 2 exhibits superior hydrogen evolution reaction performances. [ABSTRACT FROM AUTHOR]

For electrochemical water splitting, the development of low‐cost, efficient, and robust electrocatalysts for both the oxygen evolution reaction and hydrogen evolution reaction remains challenging. Herein, we report stoichiometric ternary‐phase CoPS with a two‐dimensional ultrathin porous nanosheet structure as an efficient bifunctional electrocatalyst for overall water splitting. Owing to the stable stoichiometric ternary phase, abundant octahedral Co3+ is observed in CoPS, serving as active sites to boost electrocatalytic activities. With the introduction of the ultrathin porous nanosheet structure, more active sites are exposed to enhance the electrochemical performance. Therefore, the samples display remarkable oxygen evolution activity with a low overpotential of 316 mV at 10 mA cm−2 and a small Tafel slope of 50.2 mV dec−1. Combined with their highly efficient hydrogen evolution activity, CoPS ultrathin porous nanosheets are demonstrated to have extraordinary activities for overall water splitting, with a cell voltage of 1.57 V to reach 10 mA cm−2 current density. This work not only provides a bifunctional catalyst with outstanding performance, but also offers a facile route for improving electrocatalytic activity by synergistic morphology design and electronic modulation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • WS 2 /W electrodes completely remove contact resistance effect on the charge transfer. • WS 2 nanosheets have high surface areas and abundant active sites. • WS 2 exhibits good electrical conductivity. • WS 2 /W heterojunction shows remarkably enhanced electrocatalytic HER activity. Abstract In this work, we report a simple bottom-up approach to synthesize seamless tungsten disulfide (WS 2)-tungsten (W) heterojunction electrode for efficient hydrogen evolution reaction (HER). Through one step sulfidation of WO 3 /W, ultra-thin vertically-arranged WS 2 flakes with high surface areas and stepped-structure as well as abundant defects can grow on the W substrate. The synthesized WS 2 /W electrode exhibits outstanding HER activity with an onset overpotential of as small as approximately 30 mV, and an operating potential of only 108 mV for 10 mA/cm2, which is close to the state-of-the-art transition metal dichalcogenides (TMDs) HER electrocatalyst reported in the literature so far. The abundant exposed edges and defects of WS 2 along with excellent electrical contact between WS 2 and W substrate contribute to the high HER activity of WS 2 /W electrode reported in this work. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 1 T-MoS 2 in-situ entrenched on N,P,S-codoped hierarchical carbon microflower. • 10 mA cm–2 HER overpotential of P-MoS 2 @HCMF is low to 86 mV. • 100 h long-term operation with negligible current deterioration. Abstract Phosphorus contained metallic 1T-MoS 2 produced from in-situ ammonium intercalation induced surface sulfur atom distortion of MoS 2 rooted in N,P,S-codoped hierarchical flowerlike carbon (HCMF) hybrids were successfully prepared via a dopamine self-polymerization together with molybdate process followed by a hydrothermal reduction route. On account of the coupling effect of metallic phase, defect-rich character, heteroatomic dopants and highly conductive carbon support, the P-MoS 2 @HCMF demonstrates prominent performances with an overpotential of merely 86 mV to deliver a current density of 10 mA cm–2 and a small Tafel slope of 42.35 mV dec–1 for hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4 , which are among the best results for molybdenum disulfide based HER catalysts. Strikingly, benefiting from S vacancies and P dopant functioning as electron donors, as well as strain arisen from the tensile of rigid carbon microflower scaffold to MoS 2 nanosheets to overcome agglomeration barriers of nanosheets, P-MoS 2 @HCMF remained well the pristine 1 T phase and exhibited superior cycling stability with indistinguishable overpotential decay over 5000 sweeps and extraordinary HER durability during the 100 h long-term operation with negligible current deterioration. These findings highlight the prospective potential of P-MoS 2 @HCMF as a highly efficient and stable noble metal-free electrocatalyst towards HER. [ABSTRACT FROM AUTHOR]

Molybdenum sulfide (MoS2) has emerged as a promising electrocatalyst for hydrogen evolution reaction (HER) owing to its high activity and stability during the reaction. However, the efficiency of hydrogen production is limited by the number of active sites in MoS2. In this work, a simple method of fabricating polycrystalline multilayer MoS2 on Mo foil for efficient hydrogen evolution is demonstrated by controlling the sulfur (S) vacancy concentration, which can introduce new bands and lower the hydrogen adsorption free energy (Δ GH). For the first time, theoretical and experimental results show that the HER performance of synthesized MoS2 with S vacancy can be further enhanced by the very small amount of platinum (Pt) decoration, which can introduce new gap states and more catalytic sites in real space with suitable free energy. The fabricated hybrid electrocatalyst exhibits significantly smaller Tafel slope of 38 mV dec−1 and better HER electrocatalytic activity compared to previous works. This approach provides a simple pathway to design low-cost, efficient and sizable hydrogen-evolving electrode by simultaneously tuning the MoS2 band structure and active sites. [ABSTRACT FROM AUTHOR]

• Critical roles of A, B-site cations, and oxygen vacancies are revealed in Bi 0.15 Sr 0.85 Co 1− x Fe x O 3−δ perovskites. • BiSC 0.8 Fe 0.2 shows excellent OER activity and marvelous durability in 0.1 M KOH. • A link between bulk properties and OER activity has been established. • The highly A-site deficient surface layer also plays a critical role in OER. Development of perovskite-type electrocatalysts with high activity, excellent durability and affordable cost provides a promising solution to promote commercialization of clean energy technologies. Here we prepared Bi 0.15 Sr 0.85 Co 1− x Fe x O 3−δ (x = 0.2, 0.4, 0.6, 0.8, 1) perovskites by the conventional solid-state reaction route, and investigated their OER electrocatalytic activity and durability in 0.1 M KOH solution to reveal the critical role of A, B-site cations and oxygen vacancies. Results show the OER activity decreases with increasing x. The optimum composition, BiSC 0.8 F 0.2 , presents impressive electrocatalytic performances with low overpotential (330 mV on rotation disk electrode, and 283 mV on carbon paper electrode at 10 mA/cm2) and excellent long-time durability showing a small increase in the overpotential of 17 mV in 167.5 h. Comprehensive analysis and discussion on the bulk and surface properties reveal the critical role of A, B-site cations and oxygen vacancies on OER, and interrelations of Co2+ fraction, oxygen non-stoichiometry and the OER overpotential have been established. Most importantly, a highly A-site deficient surface layer is found on the as-synthesized perovskite, which facilitate OER by exposing more active B-site cations. This work not only reports a promising OER electrocatalyst with high activity and superior durability, but also provides perspectives on relational design for highly efficient and stable perovskite electrocatalysts for OER using solid-state reaction method. [ABSTRACT FROM AUTHOR]

Atomically dispersed Pt on ultrafine Ru nanoclusters (∼1.46 nm) loaded by the commercial acetylene black support is fabricated by a facile one-step cold-plasma technique. The Pt single atoms on Ru nanoclusters electrocatalyst (Pt 0.47 -Ru/Acet) with 0.47 wt% content of Pt exhibits an excellent HER activity in all pH, achieving ultralow overpotential of only 17, 28, and 8 mV at 10 mA·cm−2 in 1 M KOH, 0.5 M H 2 SO 4 , and 1 M PBS, respectively. [Display omitted] • Cold plasma enables ultrafine Ru nanoclusters compared with calcination method. • Atomically dispersed Pt-modified Ru is fabricated by a cold-plasma technique. • Pt 0.47 -Ru/Acet displays excellent pH-universal HER activity. • DFT calculations reveal the mechanism of Pt enhancement in alkaline HER. • Both anode and cathode use Pt 0.47 -Ru/Acet in solar-driving water splitting. Exploring highly active and stable electrocatalyst using trace noble metals for hydrogen evolution reaction (HER) is urgently needed but still challenging. Here, atomically dispersed Pt on ultrafine Ru nanoclusters (∼1.46 nm) loaded by the commercial acetylene black (Acet) support is fabricated by a facile one-step cold-plasma technique. The Pt single atoms on Ru nanoclusters electrocatalyst (Pt 0.47 -Ru/Acet) with 0.47 wt% content of Pt exhibit an excellent HER activity in all pH, achieving ultralow overpotential of only 17, 28, and 8 mV at 10 mA·cm−2 in 1 M KOH, 0.5 M H 2 SO 4 , and 1 M PBS, respectively. And the mass activity of Pt 0.47 -Ru/Acet catalyst in alkaline is about 5.54 and 2.15 times that of commercial Ru/C and Pt/C catalyst at an overpotential of 100 mV, respectively. Meanwhile, after 8000 CV cycles, there is barely performance decrease for Pt 0.47 -Ru/Acet, displaying good stability. DFT calculation reveals that the Pt single atoms could effectively regulate the electronic structure of Ru clusters, and reduce the energy barriers of water dissociation (Volmer step) as well as subsequent hydrogen evolution (Heyrovsky step), thus enhancing the alkaline HER performance effectively. This work provides an effective approach to designing a high-performance HER electrocatalyst with the atomic-dimension Pt surface modification. [ABSTRACT FROM AUTHOR]

The catalytic activity of noble-metal nanoparticles (NPs) often has closely connection with their sizes and geometric shape. In the work, polyhedral NPs of palladium (Pd) with controlled sizes, shapes, and different proportions of {100} to {111} facets on the surface were prepared by a seed-mediated approach. Electrochemical experiment demonstrates that the catalytic performance of the Pd nanocubes (NCs) enclosed by {100} facets is more active than Pd octahedrons enclosed by {111} facets for the hydrogen evolution reaction (HER), which is consistent with density functional theory (DFT) calculation results. Meanwhile, with the assistance of a polyethyleneimine–reduced graphene oxide (PEI–rGO) support, the examined Pd cube/PEI–rGO 50:1 (10 wt. %) electrocatalyst presents outstanding HER activity comparable with that of commercial Pt/C catalyst. This correlation between the HER catalytic activity and surface structure will contribute to the reasonable design of Pd catalysts for HER with high efficiency and low metal loading. [ABSTRACT FROM AUTHOR]

Design and synthesis of non-precious-metal catalyst for efficient electrochemical transformation of water to molecular hydrogen in acid environments is of paramount importance in reducing energy losses during the water splitting process. Here, the hybrid material of MoS 2 -coated Cu loaded on the multi-walled carbon nanotubes (MWCNTs@Cu@MoS 2 ) was synthesized using chemical process and hydrothermal method. It was found that the participation of MWCNTs and Cu nanoparticles not only improved the electrical conductivity of the catalyst, but also further enhanced the catalytic activity by synergistic effect with edge-exposed MoS 2 -coating. Electrochemical experiments demonstrated that the catalyst exhibited excellent hydrogen evolution reaction (HER) activity with large cathode currents (small overpotential of 184 mV for 10 mA cm −2 current density) and a Tafel slope as small as 62 mV per decade. Furthermore, it was discovered that the current density of this composite catalyst had a little decrease after the continual 1000 cycling, which showed the catalyst had a high stability in the recycling process. These findings confirmed that this catalyst was a useful and earth-abundant material for water splitting. [ABSTRACT FROM AUTHOR]

• Pt SACs with adjusted dopant were fabricated by varying plasma gas and duration. • DFT predicted Pt-N coordination affected the adsorption free energy of H* (ΔG*). • Pt-C 2 N 1 O 1 moiety exhibits the lowest ΔG* value of 0.04 eV. • PtSA/C-Air presented the optimal HER activity with a TOF of ∼13 H 2 s−1 at 40 mV. • Pt coordination, electron transfer, p-band center, and ΔG* were correlated. Coordination tunability of the single-atom catalysts (SACs) is an essential but challenging issue for the catalyst sifting and structure-activity relationship analysis. Herein, Pt single atoms with tunable coordination are readily achieved via a facile cold-plasma technique by changing the gas type (N 2 , Ar, or Air) and treatment duration. Combining with density functional theory calculation, the Pt-N coordination concentration is predicted to be highly correlated with adsorption free energy of H* atoms (ΔG H*) for the hydrogen evolution reaction (HER), which is further validated experimentally. Remarkably, the sample with N, O co-dopant introduced by air plasma exhibits a high TOF of ∼13 H 2 s−1 at 40 mV, and outstanding mass activity of 7.41 A mg−1 Pt for HER, which is 26.5 times of commercial Pt/C catalyst. The enhanced performance might originate from the optimized electronic structure of active carbon site with moderate electron transfer and p-band center, which enables a suitable binding strength with H* and thus a near-zero ΔG H*. [ABSTRACT FROM AUTHOR]

[Display omitted] Construction of heterogeneous interfaces with dual active components to synergistically promote both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is an effective strategy for facilitating electrochemical water splitting, but the appropriate active component regulation via simple synthesis procedures is still challenging. Herein, the Co and Co 2 Mo 3 O 8 active components are screened to construct effective heterogeneous interfaces and successfully integrated on Ni foam by thermal reduction of cobalt molybdate precursor. And this bifunctional electrode (Co/Co 2 Mo 3 O 8 /NF) required overpotentials of only 164 and 360 mV to drive the 100 mA cm−2 for HER and OER in alkaline media, respectively. Theoretical calculations showed that the electron transfer occurred from Co to Co 2 Mo 3 O 8 at the interface, then the formed interfacial cobalt atoms with deficient electron were beneficial for water activation, and reduced energy barrier of water dissociation under the synergistic effect of Co 2 Mo 3 O 8. Notably, the alkaline electrolyzer based on symmetric Co/Co 2 Mo 3 O 8 /NF electrodes generated 100 mA cm−2 at a voltage of only 1.75 V, surpassing commercially available precious-metal Pt/RuO 2 -based catalysts. [ABSTRACT FROM AUTHOR]

The exploitation of a new adsorbent with a high adsorption performance and recyclability is of great practical significance for the treatment of wastewater containing mercury ions. In this study, a novel membrane adsorbent was fabricated by blending MoS 2 nanosheets into a PVDF polymer matrix (P-PVDF/MoS 2) followed by non-solvent-induced phase conversion. This material was able to bind mercury ions and was not affected by the solution ionic strength, co-existing anions, or interfering heavy metal ions. The optimal pH range for mercury ion elimination was 4.5–6.0, and P-PVDF/MoS 2 exhibited a maximum adsorption capacity of 578 mg g−1. The pseudo-second-order adsorption kinetics and Langmuir isotherm models best described the adsorption process. The adsorption mechanism was mainly monolayer chemisorption, for which the S groups were the major active sites. Furthermore, the membrane could be removed from the aqueous solution easily using tweezers, and the removal efficiency of mercury ions remained over 90% after ten cycles. This study suggests that the inexpensive and recyclable P-PVDF/MoS 2 membranes can be used for the efficient removal of heavy metal ions from wastewater at a large scale. Image 1 • One-step blending fabrication of novel P-PVDF/MoS 2 adsorption membrane. • Removal of Hg(II) with excellent adsorption capacity and reusability. • Adsorption performance is independent of the solution environment. • Chelation, precipitation, and crystal growth were involved in the adsorption. • Shows potential in large-scale practical application for Hg(II) removal. The main finding of the work: The present work, for the first time, reports a PVDF composite membrane decorated by MoS 2 nanosheets that could remove Hg(II) ions selectively from water with high efficiency, inexpensive cost, and recyclability. [ABSTRACT FROM AUTHOR]

[Display omitted] Hydrogen energy is expected to replace fossil fuels as a mainstream energy source in the future. Currently, hydrogen production via water electrolysis yields high hydrogen purity with easy operation and without producing polluting side products. Presently, platinum group metals and their oxides are the most effective catalysts for water splitting; however, their low abundance and high cost hinder large-scale hydrogen production, especially in alkaline and neutral media. Therefore, the development of high-efficiency, durable, and low-cost electrocatalysts is crucial to improving the overpotential and lowering the electrical energy consumption. As a solution, Ni 2 P has attracted particular attention, owing to its desirable electrical conductivity, high corrosion resistance, and remarkable catalytic activity for overall water splitting, and thus, is a promising substitute for platinum-group catalysts. However, the catalytic performance and durability of raw Ni 2 P are still inferior to those of noble metal-based catalysts. Heteroatom doping is a universal strategy for enhancing the performance of Ni 2 P for water electrolysis over a wide pH range, because the electronic structure and crystal structure of the catalyst can be modulated, and the adsorption energy of the reaction intermediates can be adjusted via doping, thus optimizing the reaction performance. In this review, first, the reaction mechanisms of water electrolysis, including the cathodic hydrogen evolution reaction and anodic oxygen evolution reaction, are briefly introduced. Then, progress into heteroatom-doped nickel phosphide research in recent years is assessed, and a discussion of each representative work is given. Finally, the opportunities and challenges for developing advanced Ni 2 P based electrocatalysts are proposed and discussed. [ABSTRACT FROM AUTHOR]

1D/2D CdS-Ti 3 C 2 T x photocatalyst has been synthesized via a facile electrostatic self-assembly approach for application toward photoredox coupling selective ethanol conversion and H 2 evolution under acidic conditions, in which Ti 3 C 2 T x MXene plays multi-roles in enhancing the photocatalytic performance of the binary composites. • 1D/2D CdS-Ti 3 C 2 T x MXene composite is prepared via one-step electrostatic self-assembly. • CdS-Ti 3 C 2 T x MXene is applied to photoredox coupling bioethanol conversion and H 2 evolution. • CH(OH)CH 3 is proved to be the pivotal radical species during photocatalytic process. • Ti 3 C 2 T x MXene plays multi-roles in enhancing photocatalytic performance of binary composites. Exploiting solar energy to photocatalyze integrated selective conversion of bioethanol into fine chemicals and hydrogen (H 2) is a promising avenue in response to current energy and environmental crises. Herein, we have reported the mild synthesis of a binary heterostructure of CdS-Ti 3 C 2 T x MXene (CdS-MX) combining one-dimensional (1D) CdS nanowires (NWs) with two-dimensional (2D) MXene structure, and its application in photocatalytic coupling redox reaction of H 2 evolution and selective conversion of bioethanol into 1,1-diethoxyethane (DEE) under acidic conditions. The results reveal that the synergistic effect of the intimate interfacial contact and matched energy level alignment between electrically conductive 2D MXene and semiconductor 1D CdS NWs benefits the separation and migration of charge carriers. Furthermore, CH(OH)CH 3 has been proven to be the pivotal radical intermediate during photoredox process. This work is anticipated to stimulate further interest on rational construction of MXene-semiconductor based composites toward photoredox coupling organic synthesis and H 2 evolution in a sustainable manner. [ABSTRACT FROM AUTHOR]

[Display omitted] Enhancing double-phase mass transfer capability and reducing overpotential at high currents are critical in the oxygen evolution reaction (OER) catalyst design. In this work, nickel–iron layered double hydroxide (NiFe-LDH) loaded on nickel foam (NF) was used as a self-sacrificing template for subsequent growth of nickel–iron Prussian blue (NiFe-PBA) hollow nanocubes on its sheet arrays. The triple-scale porous structure is therefore in -situ constructed in the produced NiFe-PBA@LDH/NF catalyst, where NiFe-PBA nanocubes, NiFe-LDH sheets and NF skeletons provide pores at hundred-nanometers, microns and hundred-microns, respectively. Due to the successful construction of hierarchical mass transfer channels in the catalyst, the overpotential required to deliver 1000 mA cm−2 OER is only 396 mV, which is 80 mV lower than that of NiFe-LDH/NF with a double-scale porous structure, manifesting the importance of the appropriate mass transfer channels, promoting the potential application of the NiFe-PBA@LDH/NF catalyst in industrial-scale electrolysers. [ABSTRACT FROM AUTHOR]

Amorphous molybdenum sulfide (MoSx) is a highly active noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER). The MoSx was prepared by electrochemical deposition at room temperature. Low-cost precursors of Mo and S were adopted to synthesize thiomolybdates solution as the electrolyte. It replaces the expensive (NH)2MoS4 and avoid the poison gas (H2S) to generate or employ. The (MoO2S2)2−, (MoOS3)2− and (MoS4)2− ions were determined by UV–VIS spectroscopy. The electrodeposition of MoSx was confirmed with XRD, XPS and SEM. The electrocatalyst activity was measured by polarization curve. The electrolyte contained (MoO2S2)2− ion and (MoOS3)2− ion electrodeposit the MoSx thin film displays a relatively high activity for HER with low overpotential of 211 mV at a current density of 10 mA cm−2, a relatively high current density of 21.03 mA cm−2 at η = 250 mV, a small Tafel slope of 55 mV dec−1. The added sodium dodecyl sulfate (SDS) can efficient improve the stability of the MoSx film catalyst. [ABSTRACT FROM AUTHOR]

Loading 2D layered transition metal dichalcogenides (TMDs) on p‐type silicon photocathode is suitable for hydrogen production in solar‐driven photoelectrochemical (PEC) water splitting. Similarly, various nanostructured TMDs exposing more active sites are widely explored for improving the PEC performances of composite photoelectrodes. Here, defect engineering using a controllable argon ion beam bombardment is presented on ReS2/Si photocathode. The atomic vacancy defects are introduced on the 2D ReS2 to realize high‐density active sites, which significantly enhance the solar‐driven hydrogen evolution reaction performance of ReS2/Si photocathode. The highest photocurrent density of 18.5 mA cm−2 (at 0 V vs reversible hydrogen electrode) is achieved, under a simulated sun irradiation. High‐density ReS2 nanosheets are directly grown on p‐Si substrates as ReS2/Si photocathodes. A controllable Ar ion beam bombardment is employed to introduce Re vacancy defects on the ReS2 nanosheets. The defect engineered ReS2/Si photocathode exhibits greatly enhanced photoelectrochemical–hydrogen evolution reaction (PEC–HER) performances with the optimum value of −18.5 mA cm−2 at 0 V versus RHE. [ABSTRACT FROM AUTHOR]

Developing high-efficiency and cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for hydrogen production from electrolysis. Herein, a facile and universal strategy for fabricating organophosphorus (OP) layer encapsulated layered double hydroxide (LDH) is proposed for robust freshwater/seawater oxidation. This approach is based on a self-growing strategy using phytic acid (PA) to realize superb OER activity due to the electron transfer from metal ions in LDH to the phosphate groups in the OP layer. The phosphate group enriched OP layer can also efficiently avoid chloride corrosion via "physical blocking" and "electrostatic repelling", enabling the OP-NiCo-LDH catalyst to show durable seawater oxidation catalysis performance. It requires an overpotential of 330 mV to deliver a 500 mA cm-2 seawater oxidation with excellent durability for 500 h. Moreover, only 1.59 V is required to achieve a 500 mA cm-2 overall seawater splitting for OP-NiCo-LDH||NiMoN cell. The refore, this work provides a strategy to design robust OER catalysts for industrial water/seawater electrolysis. [Display omitted] • A self-grwong strategy to fabricating organophosphorus (OP) layer on LDH. • The phosphate group enriched OP layer can bi-functionally avoid chloride corrosion in seawater. • superb OER activity and stability are achieved in both fresh water and seawater. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We successfully synthesized sea urchin-like ternary cobalt phosphosulfide (CoPS). • CoPS is a high-efficiency bifunctional electrocatalyst for overall water splitting. • DFT calculations reveal the mechanism that CoPS has favorable performance for OER and HER. Abstract The development of efficient non-noble bifunctional electrocatalysts for the overall water splitting is a pressing and challenging task. In this work, we report a sea urchin-like cobalt phosphosulfide (CoPS) ternary compound for overall water splitting. Because CoPS contains more than one nonmetallic element, ternary compounds possess dianions might lead to modulated electronic structure and thus modified their electrocatalytic properties. Our DFT calculation results reveal that the ternary CoPS exhibits favorable performance for both the oxygen evolution reaction and hydrogen evolution reaction. Experimentally set as cathode and anode in a full cell for overall water splitting, the CoPS cell needs a voltage of only ∼1.59 V to reach a current density of 10 mA cm−2 and has outstanding stability. Our results open up a path to search for alternative bifunctional electrocatalyst materials to substitute for noble metals in overall water splitting. [ABSTRACT FROM AUTHOR]

Ni/Mo 2 C hetero-sheet arrays are grown vertically on nickel foam skeleton to utilize the advantages of Ni and Mo 2 C on promotion of HER kinetics and 3D structure on mass transfer and accessibility and only 151 and 271 mV overpotentials are needed to deliver 100 and 1000 mA/cm2 HER, respectively. [Display omitted] • Ni-doped Mo 2 C nanosheet arrays are grown vertically on nickel foam skeleton. • Polyvinylpyrrolidone is used as soft template for catalyst preparation. • 151 and 271 mV overpotentials are needed to deliver 100 and 1000 mA/cm2 HER. • The HER can stably operate for more than 500 h. Practical structural design and electronic regulation are significant for synthesising efficient electrocatalysts. Therefore, a facile soft-template approach has been applied to successfully grow Ni/Mo 2 C heterojunction nanosheet arrays on nickel foam (NF) skeleton (NS-Ni/Mo 2 C@NF) using polyvinylpyrrolidone (PVP) as a soft template. The density functional theory (DFT) calculations reveal that abundant Ni/Mo 2 C heterojunction in NS-Ni/Mo 2 C@NF can provide many active sites with a moderate hydrogen adsorption free energy (ΔG H* , 0.037 eV). Benefiting from this nanosheet array structure and abundant Ni/Mo 2 C heterojunctions, the NS-Ni/Mo 2 C@NF catalyst can efficiently catalyze HER, especially at large current densities. As a result, only 151 and 271 mV overpotentials are needed to deliver 100 and 1000 mA/cm2 HER, respectively. More importantly, the hydrogen production testing with NS-Ni/Mo 2 C@NF as the working electrode can run stably for 500 h without activity decay under the current density of 500 mA/cm2 commonly used in industrial water electrolyzers, indicating that NS-Ni/Mo 2 C@NF has broad application prospects. [ABSTRACT FROM AUTHOR]

The process of water splitting by using efficient non-precious-metal catalyst to make the process economically viable has brought forward an extensive research. In this study, the composite of Cu and MoS 2 on the reduced graphene oxide (rGO) (Cu–MoS 2 /rGO) with high catalytic activity toward hydrogen evolution reaction (HER) was easily synthesized using hydrothermal method and chemical process. It was found that the participation of rGO improved the electrical conductivity of the catalyst, and the MoS 2 nanoflowers (NFs) with a higher number of exposed edges exhibited higher HER activity. In addition, the addition of Cu particles could not only enhance the electrical conductivity of the catalyst, but also further improved the catalytic activity by synergistic effect with MoS 2 NFs. Electrochemical experiments demonstrated that the catalyst exhibited excellent HER activity with large cathode currents and a Tafel slope as small as 90 mV decade −1 . Furthermore, it was discovered that the current density of this composite catalyst had a little decrease after the continual 700 cycling, which showed the catalyst had a high stability in the recycling process. These findings confirmed that this catalyst was a useful and earth-abundant material for water splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel FOR mediated Li electrolysis recovery method is proposed. • Adsorption strength of the intermediate HCOO on Cu-based oxide is low to −0.36 eV. • Only 1.543 V vs. RHE is required to deliver 500 mA cm−2 FOR. • Hydrogen production coupled Li recovery can be experimentally achieved. In response to the increase in retired lithium-ion batteries (LIBs), there is a rising trend in lithium recycling, which can not only address the scarcity of lithium resources but also mitigate environmental pollution caused by battery waste. In this study, we present an electrocatalytic strategy for formate oxidation reaction (FOR) aimed at facilitating lithium recovery coupled hydrogen production. The obtained results have indicated that the synthesized Cu-based oxide can efficiently catalyze FOR, achieving a current density of 500 mA cm−2 at only 1.534 V vs. RHE. According to density functional theory calculations, the adsorption strength of the intermediate specie HCOO on Cu-based oxide is reduced (−0.36 eV) compared to Ni-based oxide (−2.27 eV), resulting in a thermodynamically favorable step for the rate-determining HCOO dehydrogenation reaction. Assembling a FOR coupled hydrogen evolution reaction (HER) electrolysis system can achieve hydrogen production and Li recovery (Li recovery product is Li 2 CO 3) by electrolyzing alkaline raffinate containing lithium. This approach eliminates the need for additional formic acid and sodium carbonate, thereby reducing material consumption and ultimately enhancing the economic efficiency of the lithium battery recovery strategy. [ABSTRACT FROM AUTHOR]

Electrocatalytic conversion of CO 2 to syngas is an attractive pathway for transforming CO 2 into high-value chemicals, but the process still suffers from low selectivity. In our work, we construct a two-dimensional (2D) structure of Cu 2 Se-SnO heterojunction catalyst through a high-temperature thermal reduction method. The catalyst with two phases located in the same plane exhibits efficient charge transfer, and the tunable heterojunction interface acts as active sites for CO 2 adsorption and activation. Additionally, its suitable *CO adsorption energy facilitates the desorption of intermediates, leading to the formation of CO. Finally, this catalyst demonstrates excellent selectivity for syngas, maintaining a Faradaic efficiency (FE) of over 60% across a wide range of potentials (-0.67 ∼ −1.07 V vs. RHE) with adjustable syngas ratios and up to 92% FE at −0.97 V vs. RHE. This research provides a new approach for balancing reduction CO 2 and competing hydrogen evolution reaction. [Display omitted] • Cu 2 Se-SnO nanosheet heterojunction with two phases locates in the same plane. • The tunable heterojunction interface acts as active sites for CO 2 reduction. • The in-plane heterojunction can avoid the shielding of the interface. • The introduction of SnO can decrease the adsorption strength of *CO on Cu 2 Se. • This catalyst demonstrates excellent selectivity for syngas with a FE over 60%. [ABSTRACT FROM AUTHOR]

Regulating interfacial properties of electrocatalysts to enhance the performance of oxygen evolution reaction (OER) possesses practical significance for water splitting. Herein, we report a novel strategy to form a graphitic carbon nitride (g-C 3 N 4) interface layer on nickel foam (NF), followed by the growth of nickel-iron (oxy)hydroxides (NiFe-OH). The NiFe-OH nanosheets are tightly anchored on the g-C 3 N 4 layer, exhibiting enhanced surface and structural characteristics. Therefore, the as-prepared NF/g-C 3 N 4 /NiFe-OH demonstrates superior OER activity with low overpotentials of 272, 342, and 476 mV at the current densities of 50, 100, and 200 mA cm−2, respectively. The reduced Tafel slope and raised TOF values of the electrode compared to NF/NiFe-OH reveal the promoting roles of g-C 3 N 4 , which provides more active sites, induces charge redistribution, and facilitates electron transfer. Furthermore, the electrode presents reliable stability and durability without observable morphological damage, alteration in the surface chemical state, and significant depletion of active components. [Display omitted] • The in-situ strategy is used to form g-C 3 N 4 ultrathin interface layer on NF. • The g-C 3 N 4 interlayer improves surface structure and charge transport of NiFe-OH. • The promoting mechanism of g-C 3 N 4 for efficient OER of the electrode is determined. [ABSTRACT FROM AUTHOR]

Loading cocatalysts can effectively reduce the hydrogen production overpotential and provide additional catalytic sites. Fe 2 P, with abundant active sites, low hydrogen evolution overpotential, is regarded as a promising cocatalyst to replace the noble metals. Fe 2 P nanosheets were grown in situ on the surface of Cd 0.9 Zn 0.1 S nanorods to form unique 2D/1D structure, which was designed to enlarge the interface contact between them. The maximum hydrogen evolution rate was as high as 38.48 mmol h−1 g−1, which was even higher than that of noble metal Pt modified Cd 0.9 Zn 0.1 S. The results of characterization and theoretical computation demonstrated that the electronic interaction existed between Fe 2 P and Cd 0.9 Zn 0.1 S, and Fe 2 P as cocatalyst collected electrons to facilitate the transfer and separation of electrons and holes. This work investigated the transfer process of photogenerated carriers and revealed the photocatalytic mechanism through a combination of theoretical calculation and experimental characterization. [Display omitted] • Fe 2 P was grown in situ on the surface of Cd 0.9 Zn 0.1 S to form unique 2D/1D structure. • The interaction of Fe 2 P and Cd 0.9 Zn 0.1 S redistributes the interfacial charge. • The maximum H 2 evolution rate of Fe 2 P/Cd 0.9 Zn 0.1 S reached 38.48 mmol h−1 g−1. [ABSTRACT FROM AUTHOR]

The electrocatalytic seawater splitting has become an important and necessary way for large-scale hydrogen production with challenges ahead. In this review, a brief introduction to the reaction mechanism of seawater electrocatalytic process is first provided, including the cathodic hydrogen evolution reaction and the anodic oxygen evolution reaction, as well as the competitive chloride evolution reaction. Recent progress in transition metal phosphides-based catalysts for seawater electrolysis, such as phosphorus doped transition metals, binary metal phosphides, and structural engineering are then evaluated and discussed. Finally, the challenges and opportunities of transition metal phosphides are proposed and discussed. [Display omitted] • The reaction mechanism is discussed, especially for the chloride evolution reaction. • Three strategies are introduced to improve the performance of seawater electrolysis. • The challenges and prospects of seawater electrolysis are provided. [ABSTRACT FROM AUTHOR]

Self-supported defect-rich few-layered NiMn-LDH nanosheets was synthesized at room temperature via a simple and time-efficient strategy. Benefiting from the synergistic effect of the few-layered structure and Mn doping, the as-prepared f-NiMn 0.22 -LDH catalyst exhibits compelling UOR activity, requiring only 1.310/1.330/1.387 V for 10/100/400 mA cm−2 UOR, respectively, with an ultralow Tafel slope of 15.8 mV dec−1. When coupled with Pt/C, the urea-assisted water electrolysis cell only required 1.436 V to reach 100 mA cm−2 urea-assisted overall water splitting for more than 100h at room temperature. [Display omitted] • The self-supported few-layered NiMn-LDH nanosheets were facilely prepared. • The defect-rich few-layered structure exposes abundant active sites. • Mn facilitates Ni oxidation and stabilizes in-situ formed NiOOH species. • The f-NiMn 0.22 -LDH exhibits superior UOR (E 10/100/400 = 1.310/1.330/1.387 V) activity. • Superb urea-assisted OWS performance are achieved in alkaline media. Due to its low equilibrium potential, urea oxidation reaction (UOR) is an advantageous alternative to the conventional anodic water oxidation reaction (OER) for energy-saving hydrogen production. Developing energy- and time-saving methods to synthesize active and stable UOR catalysts is significant. Herein, we present a simple and time-efficient method for the direct growth of defect-rich few-layered NiMn-layered double hydroxide (NiMn-LDH) nanosheets on nickel foam at ambient temperature and pressure. The defect-rich, few-layered structure exposes numerous active sites, promoting the formation of high-oxidation state Ni species at low overpotentials. Additionally, the introduction of Mn facilitates Ni oxidation and stabilizes in-situ formed NiOOH species. The optimized f-NiMn-LDH catalyst exhibits compelling UOR activity, requiring only 1.310/1.330/1.387 V for 10/100/400 mA cm−2 UOR, respectively. When used directly in urea-assisted hydrogen production, it achieves a low cell voltage of 1.436 V for a high current density of 100 mA cm−2, representing a substantial 249 mV reduction compared to water electrolysis. This work offers a simple strategy for preparing high-performance electrocatalysts for energy-efficient hydrogen production via urea-assisted water splitting. [ABSTRACT FROM AUTHOR]

Self-confinement synthesized Ni@Mo 2 C/CN can stalely achieve 10 mA/cm2 overall urea oxidation with 1.51 V applied voltage due to the mutual promotion effect of Ni and Mo 2 C on UOR activity and HER activity. [Display omitted] • Ni@Mo 2 C/CN catalyst was synthesized via an in situ self-confinement strategy. • A mutual promotion effect of Ni and Mo 2 C on UOR activity and HER activity exists. • An applied voltage of 1.51 V can achieve 10 m A/cm2 stable overall urea oxidation. Efficient hydrogen production from water splitting is crucial for sustainable energy and yet impeded by sluggish anodic water oxidation. Urea oxidation had been considered as an alternative reaction due to its much lower oxidation potential. Rational design of highly efficient cost-effective electrocatalysts for urea oxidation is therefore urgent for hydrogen production from overall urea oxidation. Here, the Ni/Mo 2 C@CN catalyst consisting of a porous carbon shell and a heterojunction Ni/Mo 2 C core was constructed by an in situ self-confinement synthesis strategy. The mutual promotion effect of Ni and Mo 2 C can boost the urea oxidation and hydrogen evolution reactions at the same time. Only 1.51 V applied potential was needed to achieve stable 10 mA/cm2 overall urea oxidation on the Ni/Mo 2 C@CN catalyst. By considering the great stability resulting from the protective effect of the carbon shell, a practical application potential of Ni/Mo 2 C@CN in overall urea oxidation was achieved. [ABSTRACT FROM AUTHOR]

• F anions in perovskite oxide lattice can active surface O for OER catalysis. • F substituted BSCF delivers 10 mA cm−2 OER at 280 mV overpotential. • Ultra-stable chronoamperometric response prolonged for 50 h. Perovskite oxides, represented by Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF), with O anion partially substituted by F anion are designed. Introduction of F in perovskite lattice initiated the transition of Co(III) and Fe(III) species to lower oxidation states and triggered the surface O anion to be activated to highly oxidative O2−/O‒, which is deemed to be efficient active sites for oxygen evolution reaction (OER) catalysis. As a consequence, the F substituted BSCF (F-BSCF) catalyst exhibits outstanding electrocatalytic activity with overpotential of only 280 mV to deliver 10 mA cm‒2 OER, which is among the results for state-of-the-art metal oxide based catalysts. Strikingly, an stable chronoamperometric response prolonged for 100 h and an impressive cycling stability demonstrate its prominent durability, much superior to the commercial IrO 2 catalyst. These findings highlight the promising potential of F substitution as an efficient strategy for active site engineering in traditional precious metal-free OER electrocatalysts. [ABSTRACT FROM AUTHOR]

• The CoP|S has coral-like nanoporous structures and allows the release of gas evolution in nano-scale design. • Stable nanoporous CoP|S with abundant active sites are fabricated through a simple annealing method. • S-substituting can control the electronic structure and favor more suitable H adsorption of CoP|S to promote HER activity. • Nanoporous CoP|S electrodes present the improved HER performance compared with CoP. The morphology and crystallographic surface can influence the catalytic HER activity of electrocatalyst. With sufficient active sites and surface area, nanoporous materials with three-dimensional interconnected porous networks have shown the promising application in electrocatalyst. In this work, we report a simple method that can synthesize the self-supported nanoporous cobalt phosphosulfate (CoP|S) electrocatalyst. Theoretical calculation shows that the phosphorus substitution by sulfur can control the electronic structures of the active sites and accelerate charge transfer of CoP, therefore improving HER activity. The experimental study shows that nanoporous CoP|S electrodes present the improved HER performance compared with CoP in alkaline media and acidic media, respectively. [ABSTRACT FROM AUTHOR]

• Core-shell structured nanoarrays (NiTe@FeOOH) were designed and fabricated. • Catalyst exhibits outstanding overall seawater splitting performance and excellent stability. • Catalyst ranks amongst the most active electrocatalysts for seawater splitting to date. • The heterointerface and strong interaction facilitated the overall seawater splitting. Electrocatalytic seawater splitting to produce hydrogen has gained wide attention in recent years. However, their scale-up applications are still hindered by the lack of highly active, stable and low-cost electrocatalysts for the anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). In this work, core–shell structured nanoarrays (NiTe@FeOOH) were designed and constructed for efficient overall seawater splitting. The catalyst (NiTe@FeOOH) exhibited superior OER and HER activity, requiring overpotentials as low as 280 mV for OER and 282 mV for HER to achieve 100 mA cm−2 in seawater, respectively. When applied for overall seawater splitting, it only required a cell voltage of 1.79 V to achieve 100 mA cm−2, with high faradic efficiencies (FEs) of nearly 100 % for both OER and HER, as well as excellent durability over 100 h of continuous testing. Based on the characterization results, the strong interactions between NiTe and FeOOH, and the chloride repelling owing to the more negatively charged surface was verified to be the proper reasons for NiTe@FeOOH's high performance and selectivity toward OER and HER. The high performance and stability of the catalyst makes it great potential for seawater splitting. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trace Ru-doped transition metal oxides supported on CNTs (Ru-MOx/CNTs, M = Ni, Co, Cu, Mn, Fe) catalysts are prepared by ion exchange method. • Ru-NiO/CNTs exhibits an ultralow overpotential for alkaline HER. • Ru-NiO/CNTs displays 7 times mass activity (1.82 A·mg Ru -1) of Pt/C benchmark. • The promoted HER activity is originated from the enhanced H 2 O adsorption/dissociation of Ru as well as the optimized electronic structure of Ni. • Ru promotion effect shows a volcano correlation between binding energy shift and HER activity. The exploitation of highly active and durable electrocatalysts that can replace high-cost Pt/C for hydrogen evolution reaction (HER) is urgently required. The challenge lies in diminishing the usage of noble metals without sacrificing HER activity. In this work, trace Ru-doped transition metal oxides (TMOs) nanoparticles (∼7 nm) with high dispersion loaded by the carbon nanotubes (CNTs) were developed. Specifically, Ru-NiO/CNTs with a low Ru content of 0.94 wt% exhibits excellent alkaline HER activity with the low overpotential of 19 mV and 98 mV to achieve the current density of 10 mA·cm−2 and 100 mA·cm−2, respectively, outperforming Ru/CNTs counterpart and most previously Ru-based nanocatalysts. Notably, the mass activity (1.83 A·mg Ru -1) and price activity (301.51 A·dollar-1) of Ru-NiO/CNTs are separately more than 7 times and 18 times higher than that of the commercial 20% Pt/C benchmark. Moreover, the catalyst can operate without activity decay after 100 h long-term stability test. DFT calculation reveals that the synergy effects are originated from (i) the accelerated adsorption and dissociation of H 2 O by Ru, and (ii) the optimized electronic structure of Ni that tunes the H* adsorption/desorption. Furthermore, we discover that Ru-promoted HER activity shows a metal-dependent relationship (Ni ≈ Cu > Mn > Co > Fe), which can use binding energy shift (ΔE) as a highly correlated descriptor. This work may provide an insightful understanding of Ru dopant for enhanced HER activity. [ABSTRACT FROM AUTHOR]

Herein, a "chimney effect" formed on the interface between the metal oxide and nickel metal for the hydrogen evolution reaction is confirmed by using density functional theory calculations and experimental methods. • A "chimney effect" formed on the interface between the metal oxide and nickel metal for the hydrogen evolution reaction is found. • The "chimney effect" is a result of the interfacial charge transfer between the metal and metal oxide. • The chemical environment around interface makes the neighboring sites be immune to H 2 O* and OH* adsorption but tend to adsorb H* selectively. • The metal oxide/metal interface is beneficial for the smooth adsorption of H* and the easy desorption of H 2 from the catalyst surface. • Experiments further reveal the key role of the amount of chimney, i.e., the interfacial metal atoms, for the excellent HER activity. Precise atomic-level control of composition and geometric structure at the interface between two catalyst components can effectively tune the catalytic properties. Herein, we found a "chimney effect" formed on the interface between the metal oxide and Nickel metal for the hydrogen evolution reaction, using density functional theory calculations and experimental methods. This special chemical environment around the interface leads the neighboring sites to be immune to the H 2 O* and OH* adsorption and to only selectively adsorb H* properly. Meanwhile, it is also beneficial for the smooth adsorption of the reactant (H*) on the interface and the easy desorption of the product (H 2) from the catalyst surface (ΔG H* close to zero). This phenomenon appears similar to a chimney of hydrogen evolution around the metal oxide/metal interface. Such "chimney effect" is a result of the interfacial charge transfer between the metal and metal oxide, and should be the nature of the interface-induced synergistic effect in metal oxide/metal composite catalysts for HER. Experiments further confirm that the catalytic activity of metal oxide/metal composites for HER can be enhanced by increasing the amount of the chimney - the interfacial metal atoms. [ABSTRACT FROM AUTHOR]

In this study, graphitized carbon black (g-CB) curled nanoribbons (CNs) were adopted as supports for 1 T-MoS 2 /MoO 3 heterostructures to enhance electrocatalytic hydrogen evolution reaction (HER). By the dual regulation on the composition of 1 T-MoS 2 and the interfacial interactions, the well-organized 1 T-MoS 2 /MoO 3 /g-CB composites exhibited excellent electrocatalytic activity and enhanced stability for HER. The optimized 1 T-MoS 2 /MoO 3 /g-CB 27 -20% exhibited the lowest over-potential of 183 mV at the current density of 10 mA·cm−2, and the lowest Tafel slope of 64 mV·dec−1. It also displayed high stability during 1000 cycles. The enhanced electrocatalytic performance of 1 T-MoS 2 /MoO 3 /g-CB 27 -20% could be attributed to the synergistic effect of high conductivity and loop structure of g-CB CNs, which not only improved the charge mobility but also prevented the agglomeration of 1 T-MoS 2 /MoO 3 nanosheets during long-term cycling. This study broadens the family of carbon supports for electrocatalysts, which could shed light for the design and fabrication of non-noble metal catalysts with high efficiency and stability. [Display omitted] • Graphitized carbon black (g-CB) curled nanoribbons were adopted as carbon support. • 1 T-MoS 2 /MoO 3 nanosheets cover on the skeleton of g-CB CNs. • 1 T-MoS 2 /MoO 3 /g-CB 27 -20% exhibits excellent electrocatalytic HER performance. • g-CB provided synergistic effect of high conductivity and loop structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inducing lattice distortion in NiFe-LDH nanosheets by Ce-doping towards accelerating electrocatalytic oxygen evolution reaction. • The optimal NiFeCe-LDH@CP only requires 267 mV to deliver 100 mA cm−2, which is 41 mV lower than pure NiFe-LDH@CP. • NiFeCe-LDH@CP have retained their structural property after 70 h stability. • DFT calculations reveal that lattice distortion could optimize the electronic structure of the Ni element in active sites and lower the energy barrier, thus accelerating the OER. Nickel-iron layered double hydroxide (NiFe-LDH) is a promising active electrocatalyst for oxygen evolution reaction (OER). However, the development of NiFe-LDH is limited by poor electrical conductivity and inferior cycling stability. Herein, we present a structural perturbation and distinct distorted lattice strategy via Ce doping in NiFe-LDH on carbon paper (CP) (NiFeCe-LDH@CP) to boost its OER performance. Lattice distortion results in a large accessible surface area and induces more O vac , accelerating the OER by modifying the intrinsic electronic structure and optimizing the adsorption energy of intermediates. As a result, the optimized NiFeCe-LDH@CP possesses excellent stability over 70 h and can deliver the current density of 100 mA/cm2 with the overpotentials of only 267 mV, which is 41 mV lower than pure NiFe-LDH@CP. Theoretical calculations indicate that the introduction of lattice distortion into NiFe-LDH could optimize the electronic structure of the Ni element in active sites and lower the energy barrier, thus leading to a significant increase in OER activity. This work figures out the effect of lattice distortion strategy on the improvement of OER performance, which opens new perspectives on the development of defect-rich OER electrocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • A silver decorated amorphous cobalt hydr(oxy)oxide is fabricated through a pre-oxidation process. • The catalyst exhibits outstanding OER performance and excellent stability. • The catalyst ranks amongst the highest OER activity for cobalt-based catalysts of recent studies. • Ag decoration induced greater Co3+ content, higher electrochemically active specific surface area, and better electron conductivity synergistically enhance the catalytic performance. "Soft" and "flexible" amorphous materials have gained traction recently due to their self-adjustability toward environmental changes. Unfortunately, poor conductivity and limited stability seriously hamper their commercial applications. In this work, we develop an Ag-decorated amorphous and efficient oxygen evolution reaction (OER) catalyst, requiring overpotentials of only 170 and 250 mV to yield current densities of 10 and 100 mA cm−2 in a 1.0 M KOH solution, respectively. The catalyst also exhibits outstanding stability, maintaining 93.1% of its initial performance after 27 h of continuous testing. When used as an air-electrode catalyst in a zinc-air battery, it recorded a charge–discharge cycle life of 330 h at a current density of 5 mA cm−2, with a voltage gap of 0.87 V. And the Ag decoration induced better electrical conductivity, more active specific surface, and higher Co3+ content are found to be the proper reasons for the catalyst's outstanding OER performance and stability. [ABSTRACT FROM AUTHOR]

Designing low-cost, high-efficiency hydrogen evolution reaction (HER) catalysts to break the bottleneck of current electrocatalytic water splitting processes remains a formidable challenge. Here, we report a strong metal-support interaction (SMSI) effect constructed with ruthenium nanorods (Ru NRs) loaded in porous titanium nitride (TiN) nanosheet assembled hollow tube (labeled as Ru NRs/TiN). Ru NRs/TiN exhibits outstanding HER performance in 1.0 M KOH solution, requiring an overpotential of only 25 mV to achieve a current density of 10 mA cm−2, and demonstrates ultra-high mass activity (20 times than that of Pt/C) and superior turnover frequency values with respect to most Ru-based catalysts. Density functional theory calculations show that the SMSI can induce a notable charge redistribution at the Ru-TiN interface and enhance the HER activity of the catalyst. Moreover, the catalyst exhibits excellent stability (10,000 cycles without decay) due to the SMSI effect between the Ru species and the TiN support. Our work has broadened the range of support options for Ru-based catalysts for HER, and provided new insights into the SMSI engineering. [Display omitted] • The irregularly curved Ru nanorods loaded on TiN support (Ru NRs/TiN) is designed as HER catalyst. • Compared with Pt/C, Ru NRs/TiN exhibits ultra-high mass activity and superior turnover frequency values. • Strong metal-support interaction at the Ru-TiN interfaces enhances the free energy for atomic hydrogen adsorption. [ABSTRACT FROM AUTHOR]

Developing highly efficient electrocatalysts is yet an important challenge for water electrolysis. Herein, the in-situ growth of Co-doped NiSe 2 on nickel foam (Co-NiSe 2 /NF) has been synthesized. Co-NiSe 2 /NF exhibited an overpotential of 136 mV at 10 mA cm−2 with a Tafel slope of 80.9 mV dec−1. In addition, the stability testing showed 92.4% of its initial HER activity after 60 h at 10 mA cm−2. The results showed that the introduction of Co tunes the electronic structure of Co-NiSe 2 /NF, resulting in fast reaction kinetics, and an enhanced stability due to the in situ growth of NiSe 2 on the NF surface. [Display omitted] • Co-NiSe 2 /NF is prepared by in-situ growth hydrothermal method. • Co-NiSe 2 /NF catalyst shows an overpotential of 136 mV at 10 mA cm−2 with 60 h durability. • The introduction of Co changes the electronic structure to enhance catalytic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-situ reduced graphene oxide supported Ru nanoparticles is synthesized. • A stable Ru O C interface is established by a simple annealing strategy at 700 ℃. • The introduction of oxygen leads to the electron-deficient of Ru NPs. • The catalyst shows high activity and stability for the hydrogen evolution reaction. Exploring efficient and robust electrocatalysts with low cost for hydrogen evolution reaction (HER) is critical for the practical application of electrochemical water splitting. Ruthenium (Ru)-based catalysts exhibit great potential in HER, whereas the extensive application is largely hampered by the insufficient performance and durability at current stage. In addition, understanding and revealing the activity enhancement mechanism of Ru-based catalysts is still very tempting while challenging. Herein, we use the oxygen-rich functional groups of graphene oxide (GO) to adsorb Ru species and in situ generate reduced graphene oxide supported Ru nanoparticles (NPs) catalysts by annealing (Ru/rGO-700). Ru/rGO-700 exhibits low overpotential of 26 mV at 10 mA cm−2 in alkaline electrolytes, and simultaneously the strong interaction induced by the Ru-O bond between the support and the anchored Ru NPs endows the catalyst a desirable stability, thus the activity of the catalysts barely decays after 50,000 cycles of durability testing. Density functional theory (DFT) calculations demonstrate that the introduction of anionic oxygen leads to the electron-deficient characteristics of Ru NPs, which weakens the Ru-H affinity and accelerates/ or favors water dissociation and hydrogen desorption. In addition, the integrated crystal orbital Hamilton population (ICOHP) confirms that the introduction of electron holes weakens the antibonding interactions between Ru atoms, thus the stability of the catalysts is greatly improved. [ABSTRACT FROM AUTHOR]

[Display omitted] • • S, N co-doped carbon nanotube encased Co NPs (S,N-Co@CNT) is successfully prepared. • • The S,N-Co@CNT demonstrate excellent activity and durability toward ORR and OER. • • As cathode catalyst for ZAB, S,N-Co@CNT exhibits a good battery performance. • • The enhanced ORR and OER mechanism have been investigated by DFT calculations. • • S-doping efficiently regulates the oxygen adsorption energy of carbon nanotube. For the practical application of metal-air batteries, developing high-active and low-cost bifunctional oxygen reduction reaction (ORR) and oxygen evolution reduction (OER) catalysts is crucial and challenging. This study designed a unique ordered three-dimensional (3D) core–shell nanostructure bifunctional ORR and OER electrocatalysts consisting of Co nanoparticles (NPs) embedded in S, N co-doped carbon nanotubes (S,N-Co@CNT). The prepared S,N-Co@CNT exhibited excellent bifunctional electrocatalytic performance, with a high half-wave potential of 0.874 V versus reversible hydrogen electrode (RHE) toward ORR, and a low overpotential of 276 mV at 10 mA·cm−2 for the OER. The unique core–shell nanostructure has delivered considerable durability and stability in the S,N-Co@CNT, demonstrating almost no change in the potential gap between the ORR and OER after more than 5000 cycles of the accelerated durability test. Moreover, the S,N-Co@CNT serves as a high-active and low-price air–cathode catalyst for a rechargeable zinc-air battery, with a high peak power density of 171 mW·cm−2, and a long continuous charging-discharging ability. Based on mechanistic studies, the high activity of the S,N-Co@CNT was derived from the suitable oxygen adsorption energy due to the effects from S, N co-doping. The outcomes from this study offer a novel strategy to prepare non-noble metal bifunctional oxygen catalysts for metal-air batteries. [ABSTRACT FROM AUTHOR]

For the large-scale industrialization of hydrogen production from water electrolysis, cost-effective catalyst toward efficient cathodic hydrogen evolution reaction (HER) has to be developed. Mo 2 C possesses similar electronic structure to Pt and is considered as a potential alternative HER catalyst while there is still a certain distance to reach the ideal HER activity. Porous nanorod with dense Mo 2 C/MoO 2 heterointerfaces (h -Mo 2 C/MoO 2) was designed via a facile F etching strategy to utilize the electronic effect of spontaneously generated surface MoO 2 on Mo 2 C. Overpotential to deliver 100 mA/cm2 HER for h -Mo 2 C/MoO 2 is low to 152 mV, which is half of that for commercial Pt/C catalyst. Activity in terms of the HER current dentistry at 150 mV overpotential of h -Mo 2 C/MoO 2 is hence 1.23 times higher than that of Pt/C. By considering the good stability as well, the h -Mo 2 C/MoO 2 catalyst shows good application prospect in the practical alkaline water electrolysis devices. Porous nanorod with dense Mo 2 C/MoO 2 heterointerfaces was designed via a facile F etching strategy to utilize the electronic effect of spontaneously generated surface MoO 2 on Mo 2 C and the significantly boosted HER activity 1.23 times higher than that of Pt/C was achieved. [Display omitted] • Porous nanorod with dense Mo 2 C/MoO 2 heterointerfaces was synthesized. • F etching strategy was used to achieve the porous structure. • Spontaneously generated surface MoO 2 can confine the electron state of Mo 2 C. • HER activity is 1.23 times higher than that of Pt/C. [ABSTRACT FROM AUTHOR]

A binary nickel surface-modified ZnIn 2 S 4 (Ni:ZIS) composite has been synthesized via photochemical reduction approach. The synergy of improved photogenerated charge transfer behavior and Ni-assisted α-H abstraction leads to the boosted photocatalytic performance of Ni:ZIS for product-oriented alcohol oxidation integrated with hydrogen evolution. • Nickel surface modified ZnIn 2 S 4 (Ni:ZIS) composites are synthesized. • The Ni:ZIS composites exhibit enhanced photoactivity for photoredox reaction. • Ni-assisted α-H abstraction tunes the selectivity of benzyl alcohol (BA) conversion. • A tentative photocatalytic BA conversion mechanism over the Ni:ZIS composites is proposed. The photocatalytic coupling reaction can be conducted in one pot to realize the simultaneous utilization of electrons and holes, thereby obtaining value-added fine chemicals and fuels. Herein, we report a binary nickel modified ZnIn 2 S 4 (Ni:ZIS) for highly efficient photocatalytic selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD) integrated with hydrogen (H 2) evolution, in which Ni can promote photogenerated charge transfer for enhancing photoactivity. Particularly, the products of converting BA to aromatic compounds over blank ZnIn 2 S 4 (ZIS) and Ni:ZIS show a marked difference under the same reaction conditions. Hydrobenzoin (HB) is the primary product over blank ZIS. After the introduction of Ni, the formation of HB is dramatically suppressed, resulting in higher selectivity of BAD, because the introduction of Ni facilitates the α-H abstraction. In addition, an analogous phenomenon has been observed on Ni-based compounds modified ZIS, such as Ni x P and NiS. It is hoped that this work would provide a feasible paradigm for modifying the surface of photocatalysts to tune the selectivity of product-oriented alcohols oxidation coupled with H 2 evolution in water. [ABSTRACT FROM AUTHOR]

• Electron transport efficiency of catalyst-electrode system is optimized. • The adsorption/desorption of H is modified by tuning the electronic properties of the electron state of surface of MoS 2. • High HER performance in alkaline and acidic electrolyte. Metal sulfides (MoS 2) for hydrogen evolution reaction (HER) catalysts typically suffer from inert kinetics, especially in alkaline conditions, due to its improper hydrogen adsorption/desorption capability on the basal plane S atoms. However, the hydrogen adsorption/desorption can be tuned by modulating the electron state by introducing the dopants in the basal plane of MoS 2. Herein, we report a MoO 2 /MoS 2 structure for efficient HER in alkaline and acidic electrolyte. The design of this high-performance MoO 2 /MoS 2 |P electrode is verified by density functional theory (DFT) calculation. The calculation demonstrates that the electron state of ultra-thin MoS 2 can be modulated by the substitution reaction (S-O or P-O) on MoO 2 surface to optimize hydrogen binding behavior and thus promote HER kinetics. Particularly, MoO 2 /MoS 2 |P (P doped) electrode exhibits an overpotential of 45 mV for 10 mA/cm2, which is a record low value among the reported transition metal dichalcogenides (TMDs) measured in the alkaline electrolyte so far. [ABSTRACT FROM AUTHOR]

• The ternary Ni-N-P microparticles is in-situ grown through one-step phosphorization. • The ternary Ni-N-P microparticles possess high activity for catalyzing both HER and OER. • Ni-N-P microparticles based electrolyzer enables effective water splitting with high stability. The development of high-activity and low-cost electrocatalysts through simple one-step method is of vital importance for electrocatalytic water splitting, but still remains a challenge. In this work, ternary Ni-N-P microparticles, an analogue of NiC x , are in-situ grown on nickel foam through one-step phosphorization at low temperature under atmosphere of ammonia. The unique microparticles-like morphology and suitable electronic structure render them enhanced electron and mass transfer ability, ensuring superior activity and good durability in catalyzing oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) under alkaline condition. Specifically, the optimal Ni-N-P microparticles can deliver 10 mA/cm2 at the overpotential of 260 mV and 180 mV vs. reversible hydrogen electrode (RHE) for OER and HER, respectively. Additionally, only a cell voltage of 1.7 V is required to afford 10 mA/cm2 when the prepared Ni-N-P microparticles serve as both anode and cathode in two-electrode configuration for overall water splitting. The Ni-N-P microparticles hold promise as cost-effective and efficient candidate for practical water splitting devices. [ABSTRACT FROM AUTHOR]

The research on developing efficient and durable overall water splitting electrocatalysts that based on earth-abundant metals is of extreme importance, but still challenging. Herein, a facile one-pot method for constructing a class of ultrafine trimetallic oxyphosphide nanoparticles (FeCoMo P–O NPs), with the merits of rich oxygen vacancies, large electrochemical active surface (ECSA), fast electron transport and long-term stability, is reported. The optimal Fe 1 Co 3 Mo 3 P–O NPs show ultralow overpotentials of 111 mV and 231 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at the current density of 10 mA cm−2 in 1 M KOH, respectively. To get insight into the overall water splitting, the water electrolyte device, fabricated by Fe 1 Co 3 Mo 3 P–O NPs as both the cathode and anode, only requires a voltage of 1.604 V to achieve the current density of 10 mA cm−2 associated with a long-time stability for at least 50 h. Image 1 • A class of ultrafine 0D FeCoMo P–O NPs is designed via a facile hydrothermal method. • The FeCoMo P–O catalysts show enhanced electrocatalytic performance for OER and HER. • The optimal Fe 1 Co 3 Mo 3 P–O display excellent performance for overall water splitting. [ABSTRACT FROM AUTHOR]