Self-supporting hierarchically micro/nano-porous Ni_3P-Co_2P-based film with high hydrophilicity for efficient hydrogen production

Designing efficient and stable non-precious metal HER(hydrogen evolution reaction)electrocatalysts with high large current density adaptability is significant for industrial application of hydrogen production by water electrolysis.Herein,a facile strategy was developed to construct a multi-phase Ni3 P-Co₂P-(Ni-Co)film with self-supporting hierarchically micro/nano-porous structure by using bubble template method electrodeposition of self-supporting micro-porous Ni Co P film,oxygen-free annealing for phase separation producing Ni₃P-Ni-Co₂P-Co structure,and acid etching for constructing surface nano-porous structure.The effective active sites for HER was significantly increased due to the hierarchically micro/nano-porous structure,which not only enlarged the surface roughness,but enhanced the bubble detachment by improving the hydrophilicity.Meanwhile,the HER electrolysis durability was improved benefiting from the Ni₃P-Co₂P phases with high corrosion resistance(especially in acid solution)and the self-supporting film structure without binder.Consequently,the Ni Co P-OA-AE film exhibited high HER catalytic performance,which delivered a current density of 10 m A cm^-2at a low overpotential of 42.9 and 39.7 m V in 1 M KOH and 0.5 M H₂SO₄,respectively.It also possessed high long-term electrolysis durability,and the cell voltage of water electrolysis using self-supporting porous Ni Co P-OA-AE||Ir O₂-Ta₂O₅ electrolyzer at 500 m A cm^-2for 250 h in 0.5 M H₂SO_(4 )is only 2.9 V.     

Chemical vapor deposition of amorphous molybdenum sulphide on black phosphorus for photoelectrochemical water splitting

Non-precious metal electrocatalyst molybdenum sulphide(MoS) and black phosphorus(BP) are highly promising catalysts for H₂ evolution reaction(HER).However,BP is environmentally unstable and the basal planes of crystal MoS₂ are inactive toward HER.Herein,amorphous molybdenum sulphide(MoSx)directly on BP/BiVO4 film dramatically improves the performance of photoelectrochemical water splitting compared with pure BiVO4.Additionally,we demonstrate that a BP layer,inserted between the MoSx and BiVO4,can enhance the photoelectrochemical performance and improve the stability of the electrodes.Finally,MoS_x/B P/BVO electrode shows the excellent current density of 2.1 mA/cm² at the potential of 1.2 V(vs Ag/AgCl),which is twice higher than that of pure BVO electrode.Our novel nanostructure materials will lead to a new class of non-precious metal photocatalysts for hydrogen production.     

Enhanced photoelectrochemical cathodic protection performance of MoS_2/TiO_2 nanocomposites for 304 stainless steel under visible light

In this work,TiO₂nanotube arrays(NTAs)sensitized with MoS₂microspheres(MoS₂/TiO₂nanocomposites)were prepared on a flat Ti substrate via two-step anodization and hydrothermal method sequentially.TiO₂NTAs were composed of many orderly nanotubes,whose large specific surface area was favorable for light absorption and MoS₂microsphere adhesion.The MoS₂microsphere as a narrow band gap semiconductor extended the TiO₂NTAs’absorption band edge to the visible region.The 2D structure of MoS₂microspheres and the construction of heterojunction electronic field at the interface of MoS₂microspheres and TiO₂NTAs promoted the separation of photoinduced carriers.The MoS₂/TiO₂nanocomposites could provide higher photoelectrochemical cathodic protection for 304 stainless steel(304 SS)under visible light than pristine TiO₂NTAs.     

基于简易微波方法制备高性能MoS2/石墨烯纳米复合材料用于高效析氢反应（英文）

用于析氢反应(HER)的低成本、高效能催化剂对于推进基于清洁氢气的能源工业非常重要.二维二硫化钼(MoS2)具有显著的催化性能,因而已被人们广泛深入研究.然而,大多数现有的合成方法耗时、复杂且效率较低.本文通过超快(60秒)微波引发的方法生产MoS2/石墨烯催化剂.石墨烯的高比表面积和导电性为MoS2纳米片的生长提供了有利的导电网络和快速电荷转移动力.文中制备的MoS2/石墨烯纳米复合材料在酸性介质中对HER表现出优异的电催化活性,具有62 mV的低起始电位,高阴极电流和43.3mV/dec的Tafel斜率.除了优异的催化活性外, MoS2/石墨烯还具有较长的循环稳定性,在250 mV的过电位下阴极电流密度高达1000 mA cm^-2.此外, MoS2/石墨烯催化剂在30–120°C范围内具有出色的HER活性和36.51 kJ mol^-1的低活化能,提供了潜在的大批量生产和制备的机会.     

Preparation of High‐Percentage 1T‐Phase Transition Metal Dichalcogenide Nanodots for Electrochemical Hydrogen Evolution

Nanostructured transition metal dichalcogenides (TMDs) are proven to be efficient and robust earth‐abundant electrocatalysts to potentially replace precious platinum‐based catalysts for the hydrogen evolution reaction (HER). However, the catalytic efficiency of reported TMD catalysts is still limited by their low‐density active sites, low conductivity, and/or uncleaned surface. Herein, a general and facile method is reported for high‐yield, large‐scale production of water‐dispersed, ultrasmall‐sized, high‐percentage 1T‐phase, single‐layer TMD nanodots with high‐density active edge sites and clean surface, including MoS₂, WS₂, MoSe₂, Mo_0.5W_0.5S₂, and MoSSe, which exhibit much enhanced electrochemical HER performances as compared to their corresponding nanosheets. Impressively, the obtained MoSSe nanodots achieve a low overpotential of ?140 mV at current density of 10 mA cm^?2, a Tafel slope of 40 mV dec^?1, and excellent long‐term durability. The experimental and theoretical results suggest that the excellent catalytic activity of MoSSe nanodots is attributed to the high‐density active edge sites, high‐percentage metallic 1T phase, alloying effect and basal‐plane Se‐vacancy. This work provides a universal and effective way toward the synthesis of TMD nanostructures with abundant active sites for electrocatalysis, which can also be used for other applications such as batteries, sensors, and bioimaging.     

Unveiling Active Sites for the Hydrogen Evolution Reaction on Monolayer MoS2

Here, the hydrogen evolution reaction (HER) activities at the edge and basal‐plane sites of monolayer molybdenum disulfide (MoS₂) synthesized by chemical vapor deposition (CVD) are studied using a local probe method enabled by selected‐area lithography. Reaction windows are opened by e‐beam lithography at sites of interest on poly(methyl methacrylate) (PMMA)‐covered monolayer MoS₂ triangles. The HER properties of MoS₂ edge sites are obtained by subtraction of the activity of the basal‐plane sites from results containing both basal‐plane and edge sites. The catalytic performances in terms of turnover frequencies (TOFs) are calculated based on the estimated number of active sites on the selected areas. The TOFs follow a descending order of 3.8 ± 1.6, 1.6 ± 1.2, 0.008 ± 0.002, and 1.9 ± 0.8 × 10^?4 s^?1, found for 1T′‐, 2H‐MoS₂ edges, and 1T′‐, 2H‐MoS₂ basal planes, respectively. Edge sites of both 2H‐ and 1T′‐MoS₂ are proved to have comparable activities to platinum (≈1–10 s^?1). When fitted into the HER volcano plot, the MoS₂ active sites follow a trend distinct from conventional metals, implying a possible difference in the reaction mechanism between transition‐metal dichalcogenides (TMDs) and metal catalysts.     

Zirconium‐Regulation‐Induced Bifunctionality in 3D Cobalt–Iron Oxide Nanosheets for Overall Water Splitting

The design of high‐efficiency non‐noble bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is paramount for water splitting technologies and associated renewable energy systems. Spinel‐structured oxides with rich redox properties can serve as alternative low‐cost OER electrocatalysts but with poor HER performance. Here, zirconium regulation in 3D CoFe₂O₄ (CoFeZr oxides) nanosheets on nickel foam, as a novel strategy inducing bifunctionality toward OER and HER for overall water splitting, is reported. It is found that the incorporation of Zr into CoFe₂O₄ can tune the nanosheet morphology and electronic structure around the Co and Fe sites for optimizing adsorption energies, thus effectively enhancing the intrinsic activity of active sites. The as‐synthesized 3D CoFeZr oxide nanosheet exhibits high OER activity with small overpotential, low Tafel slope, and good stability. Moreover, it shows unprecedented HER activity with a small overpotential of 104 mV at 10 mA cm^?2 in alkaline media, which is better than ever reported counterparts. When employing the CoFeZr oxides nanosheets as both anode and cathode catalysts for overall water splitting, a current density of 10 mA cm^?2 is achieved at the cell voltage of 1.63 V in 1.0 m KOH.     

Self-assembly of 0D/2D homostructure for enhanced hydrogen evolution

Efficient exfoliation of layered materials has attracted considerable attention in various applications due to their superior photoelectric, physical and chemical properties. Here, we report a universal, rapid approach to prepare the two-dimensional (2D) nanosheets and zero-dimensional (0D) quantum dots (QDs) using a simple cryo-mediation liquid phase exfoliation of layered materials (graphite, MoS₂, WS₂). The QDs decorated nanosheets 0D/2D homostructure can be subsequently formed by the self-assembly of the as-exfoliated QDs and nanosheets. The unique structural properties of the mono- or few-layer mesoporous nanosheets interspersed with QDs can expose abundant active edge sites as well as improve the conductivity, which exhibits excellent activity and stability towards electrocatalytic hydrogen evolution reaction (HER). This work offers a powerful methodology to prepare 2D homostructures from a variety of layered materials.     

Structurally Deformed MoS2 for Electrochemically Stable,Thermally Resistant,and Highly Efficient Hydrogen Evolution Reaction

The emerging molybdenum disulfide (MoS₂) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade‐off between catalytic activity and long‐term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature‐sensitive chemically exfoliated MoS₂ (ce‐MoS₂) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical‐transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity‐induced‐self‐crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical‐, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.     

Catalytically enhanced thin and uniform TaS<Subscript>2</Subscript> nanosheets for hydrogen evolution reaction

Though the transition-metal dichalcogenides (TMDs) were proven to have a better performance on the hydrogen evolution reaction (HER), the bulk production of active TMD materials remains a challenging work. This report overcomes those barriers by showing a simple procedure to synthesize TaS₂ nanosheets through modifying the arc discharge process. The usage of chloride as the transporting agent reduces the growth period of the formed TaS₂ with active edge sites. TaS₂ is found to have a uniform thickness (4 nm) with high crystallinity and adopt a 2H polytype (double-layered hexagonal) structure. The as-synthesized TaS₂ has superior activity for HER with the potential of 280 mV.     

In Situ Porousized MoS2 Nano Islands Enhance HER/OER Bifunctional Electrocatalysis

2D molybdenum disulfide (MoS₂) is developed as a potential alternative non-precious metal electrocatalyst for energy conversion. It is well known that 2D MoS₂ has three main phases 2H, 1T, and 1T′. However, the most stable 2H-phase shows poor electrocatalysis in its basal plane, compared with its edge sites. In this work, a facile one-step hydrothermal-driven in situ porousizing of MoS₂ into self-supporting nano islands to maximally expose the edges of MoS₂ grains for efficient utilization of the active stable sites at the edges of MoS₂ is reported. The results show that such active, aggregation-free nano islands greatly enhance MoS₂'s hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctional electrocatalytic activities. At a low overpotential of 248 and 300 mV, the porous MoS₂ nano islands can generate a current density of 10 mA cm⁻² in HER and OER, which is much better than typical nanosheet morphology. Surprisingly, the porous MoS₂ nano islands even exhibit better performance than the current commercial RuO₂ catalyst in OER. This discovery will be another effective strategy to promote robust 2H-phase, instead of 1T/1T′-phase, MoS₂ to achieve efficient endurable bifunctional HER/OER, which is expected to further replace precious metal catalysts in industry.     

Engineering 2D Metal–Organic Framework/MoS2 Interface for Enhanced Alkaline Hydrogen Evolution

2D metal–organic frameworks (MOFs) have been widely investigated for electrocatalysis because of their unique characteristics such as large specific surface area, tunable structures, and enhanced conductivity. However, most of the works are focused on oxygen evolution reaction. There are very limited numbers of reports on MOFs for hydrogen evolution reaction (HER), and generally these reported MOFs suffer from unsatisfactory HER activities. In this contribution, novel 2D Co‐BDC/MoS₂ (BDC stands for 1,4‐benzenedicarboxylate, C₈H₄O₄) hybrid nanosheets are synthesized via a facile sonication‐assisted solution strategy. The introduction of Co‐BDC induces a partial phase transfer from semiconducting 2H‐MoS₂ to metallic 1T‐MoS₂. Compared with 2H‐MoS₂, 1T‐MoS₂ can activate the inert basal plane to provide more catalytic active sites, which contributes significantly to improving HER activity. The well‐designed Co‐BDC/MoS₂ interface is vital for alkaline HER, as Co‐BDC makes it possible to speed up the sluggish water dissociation (rate‐limiting step for alkaline HER), and modified MoS₂ is favorable for the subsequent hydrogen generation step. As expected, the resultant 2D Co‐BDC/MoS₂ hybrid nanosheets demonstrate remarkable catalytic activity and good stability toward alkaline HER, outperforming those of bare Co‐BDC, MoS₂, and almost all the previously reported MOF‐based electrocatalysts.     

Metal-organic framework derived CoSe2 nanoparticles anchored on carbon fibers as bifunctional electrocatalysts for efficient overall water splitting

The development of efficient,low-cost,stable,non-noble-metal electrocatalysts for water splitting,particularly those that can catalyze both the hydrogen evolution reaction (HER) at the cathode and oxygen evolution reaction (OER) at the anode,is a challenge.We have developed a facile method for synthesizing CoSe2 nanoparticles uniformly anchored on carbon fiber paper (CoSe2/CF) via pyrolysis and selenization of in situ grown zeolitic imidazolate framework-67 (ZIF-67).CoSe2/CF shows high and stable catalytic activity in both the HER and OER in alkaline solution.At a low cell potential,i.e.,1.63 V,a water electrolyzer equipped with two CoSe2/CF electrodes gave a water-splitting current of 10 mA.cm-2.At a current of 20 mA.cm-2,it can operate without degradation for 30 h.This study not only offers a cost-effective solution for water splitting but also provides a new strategy for developing various catalytic nanostructures by changing the metal-organic framework precursors.     

Bionanofiber Assisted Decoration of Few‐Layered MoSe2 Nanosheets on 3D Conductive Networks for Efficient Hydrogen Evolution

Molybdenum diselenide (MoSe₂) has emerged as a promising electrocatalyst for hydrogen evolution reaction (HER). However, its properties are still confined due to the limited active sites and poor conductivity. Thus, it remains a great challenge to synergistically achieve structural and electronic modulations for MoSe₂‐based HER catalysts because of the contradictory relationship between these two characteristics. Herein, bacterial cellulose‐derived carbon nanofibers are used to assist the uniform growth of few‐layered MoSe₂ nanosheets, which effectively increase the active sites of MoSe₂ for hydrogen atom adsorption. Meanwhile, carbonized bacterial cellulose (CBC) nanofibers provide a 3D network for electrolyte penetration into the inner space and accelerate electron transfer as well, thus leading to the dramatically increased HER activity. In acidic media, the CBC/MoSe₂ hybrid catalyst exhibits fast hydrogen evolution kinetics with onset overpotential of 91 mV and Tafel slope of 55 mV dec^?1, which is much more outstanding than both bulk MoSe₂ aggregates and CBC nanofibers. Furthermore, the fast HER kinetics are well supported by theoretical calculations of density‐functional‐theory analysis with a low activation barrier of 0.08 eV for H₂ generation. Hence, this work highlights an efficient solution to develop high‐performance HER catalysts by incorporating biotemplate materials, to simultaneously achieve increased active sites and conductivity.     

Ruthenium Nanoparticles on Cobalt‐Doped 1T′ Phase MoS2 Nanosheets for Overall Water Splitting

2D MoS₂ nanostructures have recently attracted considerable attention because of their outstanding electrocatalytic properties. The synthesis of unique Co–Ru–MoS₂ hybrid nanosheets with excellent catalytic activity toward overall water splitting in alkaline solution is reported. 1T′ phase MoS₂ nanosheets are doped homogeneously with Co atoms and decorated with Ru nanoparticles. The catalytic performance of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is characterized by low overpotentials of 52 and 308 mV at 10 mA cm^?2 and Tafel slopes of 55 and 50 mV decade^?1 in 1.0 m KOH, respectively. Analysis of X‐ray photoelectron and absorption spectra of the catalysts show that the MoS₂ well retained its metallic 1T′ phase, which guarantees good electrical conductivity during the reaction. The Gibbs free energy calculation for the reaction pathway in alkaline electrolyte confirms that the Ru nanoparticles on the Co‐doped MoS₂ greatly enhance the HER activity. Water adsorption and dissociation take place favorably on the Ru, and the doped Co further catalyzes HER by making the reaction intermediates more favorable. The high OER performance is attributed to the catalytically active RuO₂ nanoparticles that are produced via oxidation of Ru nanoparticles.     

Edge‐Terminated MoS2 Nanoassembled Electrocatalyst via In Situ Hybridization with 3D Carbon Network

Transition metal dichalcogenides, especially MoS₂, are considered as promising electrocatalysts for hydrogen evolution reaction (HER). Since the physicochemical properties of MoS₂ and electrode morphology are highly sensitive factor for HER performance, designed synthesis is highly pursued. Here, an in situ method to prepare a 3D carbon/MoS₂ hybrid catalyst, motivated by the graphene ribbon synthesis process, is reported. By rational design strategies, the hybrid electrocatalysts with cross‐connected porous structure are obtained, and they show a high HER activity even comparable to the state‐of‐the‐art MoS₂ catalyst without appreciable activity loss in long‐term operations. Based on various physicochemical techniques, it is demonstrated that the synthetic procedure can effectively guide the formation of active site and 3D structure with a distinctive feature; increased exposure of active sites by decreased domain size and intrinsically high activity through controlling the number of stacking layers. Moreover, the importance of structural properties of the MoS₂‐based catalysts is verified by controlled experiments, validating the effectiveness of the designed synthesis approach.     

3D Nitrogen‐Anion‐Decorated Nickel Sulfides for Highly Efficient Overall Water Splitting

Developing non‐noble‐metal electrocatalysts with high activity and low cost for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of paramount importance for improving the generation of H₂ fuel by electrocatalytic water‐splitting. This study puts forward a new N‐anion‐decorated Ni₃S₂ material synthesized by a simple one‐step calcination route, acting as a superior bifunctional electrocatalyst for the OER/HER for the first time. The introduction of N anions significantly modifies the morphology and electronic structure of Ni₃S₂, bringing high surface active sites exposure, enhanced electrical conductivity, optimal HER Gibbs free‐energy (ΔG_H*), and water adsorption energy change (ΔG_H2O*). Remarkably, the obtained N‐Ni₃S₂/NF 3D electrode exhibits extremely low overpotentials of 330 and 110 mV to reach a current density of 100 and 10 mA cm^?2 for the OER and HER in 1.0 m KOH, respectively. Moreover, an overall water‐splitting device comprising this electrode delivers a current density of 10 mA cm^?2 at a very low cell voltage of 1.48 V. Our finding introduces a new way to design advanced bifunctional catalysts for water splitting.     

碳基硫化钼电催化制氢催化剂的研究进展

金属铂是目前最高效的电催化制氢催化剂,但由于铂存在高成本、低储量等缺点,难以适合广泛的工业应用。因此,寻找低成本、高储量的替代电催化制氢催化剂成为未来发展的方向。二硫化钼因具有制氢活性较高、储量丰富、易于制备等优势越来越受到关注。二硫化钼的制氢活性主要取决于暴露的催化活性位数量和导电性。因此,利用纳米碳材料的高导电性和高比表面积来提高二硫化钼的导电性和制氢催化活性位的数量,是制备高活性二硫化钼电催化剂的重要策略之一。重点介绍了二硫化钼电催化制氢的基本原理,以及采用不同碳材料,如石墨烯、氧化石墨烯、碳纳米管等,改进二硫化钼电催化制氢性能的合成方法、催化效果及反应机理。最后,展望了利用碳材料辅助制备高活性、低成本电催化制氢催化剂的前景。     

Topotactically Transformed Polygonal Mesopores on Ternary Layered Double Hydroxides Exposing Under-Coordinated Metal Centers for Accelerated Water Dissociation

Layered double hydroxides (LDHs) have been recognized as potent electrocatalysts for oxygen evolution reaction (OER), but are lacking in hydrogen evolution reaction (HER) activities due to the sluggish kinetics of water dissociation in alkaline medium. Herein, aiming to simultaneously bolster the HER and OER kinetics, a metal–organic framework (MOF) mediated topotactic transformation tactic is deployed to fabricate holey ternary CoFeNi LDHs on nickel foam, exposing polygonal mesopores with atomistic edge steps and lattice defects. The optimized catalyst requires only an external voltage of 1.49 V to afford the water splitting current density of 10 mA cm⁻² apart from the superb electrolytic stability, far surpassing the benchmark Pt/C||RuO₂ couple. More importantly, mechanistic investigations utilizing advanced spectroscopies in conjunction with density function theory (DFT) understandings unravel while the synergetic effect among under-coordinated metal centers lowers the energy barrier of water dissociation, Fe-doping enables further modulating the d-band density of states (DOS) of Co and Ni in favor of intermediates binding, thereby promoting the intrinsic HER activity. Operando Raman studies reveal negligible structural change of the LDHs during the HER process, whereas for OER the active sites can quickly turn into oxyhydroxides in the presence of lattice defects and under-coordinated metal centers.     

Hierarchical Ni3S4@MoS2 nanocomposites as efficient electrocatalysts for hydrogen evolution reaction

Hydrogen evolution reaction (HER) through water splitting is a promising way to solve the energy short-age.Noble-metal-free HER electrocatalysts with high efficiency is very important for practical applica-tions.Herein,we prepare the Ni3S4@MoS2 electrocatalyst on carbon cloth (CC) through a two-step hy-drothermal process.The Ni3S4 nanorods are uniformly integrated with the MoS2 nanosheets,forming a hierarchical structure and heterogeneous interfaces.The fast electron transfer on the interface en-hances the kinetics of catalytic reaction.The hierarchical structure provides more exposed active sites.The Ni3S4@MoS2/CC exhibits good catalytic activity and long-term stability for HER.This work provided a practicable strategy to develop efficient electrocatalysts for HER in alkaline media.