Electrocatalytic Performance For Hydrogen Evolution Reaction Research Articles

Synthesis of Stable and Efficient Electrocatalysts for Hydrogen Evolution: Hierarchical NiMo-Based Hollow Nanotubes

Large-scale development of low-cost, efficient, and stable powder electrocatalysts for the hydrogen evolution reaction (HER) in alkaline solutions is a key step toward commercial hydrogen production. Herein, a hierarchical NiMo-MoO3-x hollow nanotube (NiMo-MoO3-x-HNT) with bifunctional groups as an efficient HER electrocatalyst was strategically invented using an MoO3 nanorod (MoO3−NR) as the precursor. The synthesis mechanism of the NiMo-MoO3-x-HNT is established based on in-depth investigations using diffraction, spectral, and microscopy results. Experimental results suggest that the NiMo-MoO3-x-HNT exhibits excellent electrocatalytic HER performance in 1 M KOH, with a low overpotential of 26.5 mV@10.0 mA cm-2 and a small Tafel slope of 32.6 mV dec–1. These values are comparable to those of cutting-edge electrocatalysts based on platinum-group metals. Moreover, it exhibits an almost unaffected cyclic stability over 50,000 cycles and robust durability over 98 h. This remarkable performance is attributed to its bifunctional groups and the porous hierarchical hollow nanotubular morphology. In summary, this study proposes a novel, efficient, and cost-effective strategy for the development of noble metal-free, high-performance HER electrocatalysts.

The electrocatalytic HER activity of MoS2 decorated with adjustable-size ruthenium nanoparticles

MoS2 is a potential electrocatalytic material for its excellent durability and stability. Here, we investigate the electrocatalytic hydrogen evolution reaction performance of MoS2 nanosheets decorated with size-controlled Ru nanoparticles. The MoS2 compounded with 2.46 nm-Ru exhibits the good electrocatalytic performance with overpotential of 53 mV at 10 mA/cm2 in 0.5 M H2SO4 condition. The enhanced electrocatalytic activity of Ru@MoS2 results from accelerated charge migration between the Ru metal and MoS2 semiconductor, as well as the addition of Ru increases the number of active sites on the surface of MoS2. Furthermore, the first-principles calculations demonstrated the ΔGH* of Ru@MoS2 (−0.05 eV) is lower than P–MoS2 (2.04 eV) and the narrowed bandgap facilitates more efficient electron migration. And the theoretical calculations further reveal that the Ru nanoparticles with suitable size at the interface own the ideal ΔGH* by manipulating the D-band center of the Ru.

Aqueous pH influence on the electrocatalytic hydrogen evolution reaction with carbon nanotube-supported diiron dithiolato compound

Biomimetic chemistry on structure, function and external environment of [FeFe]-hydrogenases for hydrogen evolution reaction (HER) has shown a promising way to develop non-precious metal electrocatalysts for H2 production in the current Pt-dominated HER system. Herein, three new diiron dithiolato compounds [{(μ-SCH2)2N(C6H4CH2CO2R)}Fe2(CO)6] (R = H (1), C6H4CHO-p (2), and C6H4Me-m (3)) were first prepared and identified as a library of [FeFe]-hydrogenase models in this work. Subsequently, the as-prepared diiron molecule 2 can be covalently attached onto carbon nanotubes (CNTs), resulting in the obtainment of target CNT-supported [FeFe]-hydrogenase model labeling as covalent hybrid 2Fe2S-f-CNT. Notably, the electrocatalytic HER performance and stability of the resulted hybrid 2Fe2S-f-CNT immobilized respectively on a gassy carbon (GC) electrode are systematically studied and compared in 0.1 M KOH (pH = 13), 0.1 M phosphate buffer (pH = 7), and 0.05 M H2SO4 (pH = 1) aqueous solutions by various spectroscopic and electrochemical techniques. The result has shown that the higher electrocatalytic HER activity is observed in alkaline solution (pH = 13) relative to neutral and acidic solutions (pH = 7, 1), being attributed to the different electrochemical HER processes of diiron cluster in wide pH aqueous media as revealed by post operando analysis.

Enabling built‐in electric fields on rhenium‐vacancy‐rich heterojunction interfaces of transition‐metal dichalcogenides for pH‐universal efficient hydrogen and electric energy generation

AbstractMost advanced hydrogen evolution reaction (HER) catalysts show high activity under alkaline conditions. However, the performance deteriorates at a natural and acidic pH, which is often problematic in practical applications. Herein, a rhenium (Re) sulfide–transition‐metal dichalcogenide heterojunction catalyst with Re‐rich vacancies (NiS2‐ReS2‐V) has been constructed. The optimized catalyst shows extraordinary electrocatalytic HER performance over a wide range of pH, with ultralow overpotentials of 42, 85, and 122 mV under alkaline, acidic, and neutral conditions, respectively. Moreover, the two‐electrode system with NiS2‐ReS2‐V1 as the cathode provides a voltage of 1.73 V at 500 mA cm−2, superior to industrial systems. Besides, the open‐circuit voltage of a single Zn–H2O cell with NiS2‐ReS2‐V1 as the cathode can reach an impressive 90.9% of the theoretical value, with a maximum power density of up to 31.6 mW cm−2. Moreover, it shows remarkable stability, with sustained discharge for approximately 120 h at 10 mA cm−2, significantly outperforming commercial Pt/C catalysts under the same conditions in all aspects. A series of systematic characterizations and theoretical calculations demonstrate that Re vacancies on the heterojunction interface would generate a stronger built‐in electric field, which profoundly affects surface charge distribution and subsequently enhances HER performance.

The dependence of electrocatalytic HER activity of decorated MoS2 with Cu nanoclusters

Molybdenum disulfide is a potential electrocatalytic material for water splitting with excellent stability and durability. Here, the electrocatalytic hydrogen evolution reaction performance of Molybdenum disulfide nanosheets decorated with copper nanoclusters was investigated. The Cu@MoS2–1:10 exhibited remarkable hydrogen evolution reaction activity, with an overpotential as low as 150 mV under acidic conditions. The First-principles calculations further confirmed the superior electrocatalytic performance of Cu@MoS2, with a minimum hydrogen adsorption free energy of -0.10 eV. The improved electrocatalytic activity of Cu@MoS2 arises from the accelerated charge migration at the interface. And the addition of Cu increases the number of active sites on the surface of MoS2. This work could offer insights into the advancement of additional non-precious metals and transition metal dichalcogenides.

Multi-dimensional MoS2/S-doped-CoP heterostructure nanoarrays as an efficient electrocatalyst for hydrogen evolution reaction

Developing efficient and economical electrocatalysts for hydrogen evolution reaction (HER) over a broad pH range has received considerable attention. In this work, we prepared multi-dimensional MoS2/S-CoP heterojunction catalysts by utilizing the carbon clothes supported ZIF-67 array as templates combining with Mo-ion exchange and high-temperature phosphorization-sulfidation strategy. The introduction of MoS2 into S-CoP results in electron redistribution and the formation of a distinctive space charge region at the two-phase contact interface, thereby effectively tuning surface properties, enhancing electron conductivity, and improving electrocatalytic activity. According to Density Functional Theory (DFT) calculations, the introduction of MoS2 is advantageous for the adsorption and desorption of H*, resulting in the value of ΔGH* very close to zero. Furthermore, the adsorbed water molecules are more readily activated, rendering the ΔGH2O-dis decrease, thus significantly promoting HER activity. These features contribute to robust HER electrocatalytic performance in a wide pH range and even in seawater, which is also beneficial for industrial applications. In particular, MoS2/S-CoP exhibits superior HER performance in alkaline seawater, requiring only 197 and 228 mV to reach the current densities of 100 and 200 mA cm-2, respectively. This study offers novel perspectives on high-performance heterostructures for HER electrocatalysts in alkaline seawater environments.

Synergistic Effects of PtRhNiFeCu High Entropy Alloy Nanocatalyst for Hydrogen Evolution and Oxygen Reduction Reactions.

The unique properties of high entropy alloy (HEA) catalysts, particularly their severe lattice distortion and the synergistic effect of multiple components, endow them with exceptional multifunctional catalytic performance. Herein, it is revealed for the first time, that the ultrasmall PtRhNiFeCu HEA nanoparticles catalyst shows outstanding catalytic activity for both hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). The catalyst exhibits an impressively low overpotential of 13mV at 10mAcm-2 , a Tafel slope of 29.6mVdec-1, and high mass activity of 7.6AmgPt -1 at -50mV in alkaline media, and long-term stability of at least 20h. Moreover, the catalyst also demonstrates effective catalytic activity for acidic ORR with a commendable performance of 1.23AmgPt -1 , much exceeding the commercial Pt/C catalyst. Density functional theory (DFT) calculations unveil that the efficient electrocatalytic performance for HER and ORR can be primarily attributed to the synergistic effect between components tailors and optimizes the electronic structure of PtRhNiFeCu/C HEA, which not only enhances the HER activity through increasing water capture capability, decreasing energetic barrier for water dissociation, and optimizing hydrogen absorption but also initiates non-platinum active sites with high ORR activity, achieving the improved ORR performance.

Insights of the efficient hydrogen evolution reaction performance in bimetallic Au4Cu2 nanoclusters.

The design of efficient electrocatalysts for improving hydrogen evolution reaction (HER) performance using atomically precise metal nanoclusters (NCs) is an emerging area of research. Here, we have studied the HER electrocatalytic performance of monometallic Cu6 and Au6 nanoclusters and bimetallic Au4Cu2 nanoclusters. A bimetallic Au4Cu2/MoS2 composite exhibits excellent HER catalytic activity with an overpotential (η10) of 155 mV vs. reversible hydrogen electrode observed at 10 mA cm-2 current density. The improved HER performance in Au4Cu2 is due to the increased electrochemically active surface area (ECSA), and Au4Cu2 NCs exhibits better stability than Cu6 and Au6 systems and bare MoS2. This augmentation offers a greater number of active sites for the favorable adsorption of reaction intermediates. Furthermore, by employing X-ray photoelectron spectroscopy (XPS) and Raman analysis, the kinetics of HER in the Au4Cu2/MoS2 composite were elucidated, attributing the favorable performance to better electronic interactions occurring at the interface between Au4Cu2 NCs and the MoS2 substrate. Theoretical analysis reveals that the inherent catalytic enhancement in Au4Cu2/MoS2 is due to favorable H atom adsorption over it and the smallest ΔGH* value. The downshift in the d-band of the Au4Cu2/MoS2 composite influences the binding energy of intermediate catalytic species. This new catalyst sheds light on the structure-property relationship for improving electrocatalytic performance at the atomic level.

Strategic design of NiS2/Co3S4 heterojunction for enhanced electrocatalytic hydrogen evolution in acidic media

The construction of heterogeneous interface significantly contributes to the boosted electrocatalytic activity for hydrogen evolution reaction (HER). This enhancement is achieved through the modulation of the electronic structure, facilitation of electron redistribution, and optimization of the electrocatalyst's chemisorption towards the reaction intermediates. Herein, NiS2/Co3S4 heterojunction was synthesized using a straightforward one-pot hydrothermal method, and the impact of heterogeneous interface on the electrocatalytic HER performances was investigated. The heterogeneous interface and strengthened interfacial effects between NiS2 and Co3S4 were confirmed by HRTEM and XPS. The NiS2/Co3S4 heterojunction demonstrate significantly enhanced HER performance in acidic solutions, owing to their clever structural design and the robust interfacial coupling effects within the heterogeneous interface structure, surpassing that of single-component NiS2 materials. The optimum NiS2/Co3S4 heterojunction presents a low overpotential of 253 mV and a Tafel slope of 62.0 mV dec−1 at 10 mA cm−2 toward HER. Density functional theory (DFT) calculation indicates that NiS2/Co3S4 heterostructure exhibit lower ΔGH* values compared to NiS2 and Co3S4. This suggests that the creation of heterogeneous interface can significantly optimize the adsorption capacity for hydrogen intermediates, thereby enhancing the HER in acidic media.

Solution combustion synthesis of nanostructured Ni/W-containing electrocatalysts for hydrogen evolution reaction: The effect of fuel-to-oxidant ratio

The effect of varying fuel-to-oxidant ratio (φ) on the physicochemical properties and electrocatalytic performance for the hydrogen evolution reaction (HER) of nanostructured NiW materials produced via solution combustion synthesis (SCS) method was investigated. Agar and nickel nitrate served as the fuel and oxidant, respectively. TGA-MS results revealed that a fuel-to-oxidant ratio of 9 (φ9) provides the optimal conditions for reducing metal oxides to metallic phases due to the highest emission of reducing gas species (H2, CH4, and NH3). N2 adsorption/desorption measurements indicated that under fuel-rich conditions (φ > 1), both the specific surface area and porosity expanded with increasing the fuel quantity. Microscopy characterization was found to be consistent with N2 adsorption/desorption and TGA-MS results, revealing that the increased gas expulsion from higher fuel content led to more pronounced coral-like structures comprising of nano-sized particles and pores. Evaluation of electrocatalytic activity in an acidic medium (0.5 M H2SO4) revealed that the φ9 sample demonstrated the highest electrocatalytic HER performance. XRD and XPS analyses correlated well with this result, attributing the enhanced HER activity to the presence of the Ni0.9W0.1 metallic phase, limited oxide formation, and the highest proportions of metallic Ni and W atomic states, beyond mere surface area effects. Consequently, this study provides valuable insights into the importance of the fuel-to-oxidant ratio in optimizing the SCS method for controlled synthesis of nanostructured NiW materials in terms of morphology and composition, with implications for their potential development as high-performance, cost-effective electrocatalysts.

Two-dimensional ferroelectric heterostructures for overall water-splitting from DFT aspects

Currently, the construction of direct Z-type heterojunctions is an effective way to improve the overall water splitting catalytic efficiency of existing two-dimensional(2D) materials, which can simultaneously combine spatial separation of active sites and enhanced redox ability. In particular, when the internal structure of heterojunction was polarized, the polarization can effectively tune electronic properties and remove band gap (1.23 eV) limitation on water splitting. So far, the effect of polarization on water-splitting reactivity in heterojunctions based on the 2D layered polarized In2Y3 (Y = S, Se) and the nonpolarized 2D β-Sb monolayer is unclear. Therefore, we constructed a series of such heterojunctions and made theoretical predictions of overall water splitting performance by first-principles calculations. The predictions shown that As/In2Se3(up), Sb/In2Se3(down) and Sb/In2S3(down) are potential photocatalysts with direct Z-scheme band positions, and hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) will occur on different surfaces of system. It is found that the intrinsic polarization electric field of In2Y3 (Y = S, Se) monolayer effectively enhances photogenerated carrier driving force of reaction. Notably, the promising photocatalysts have a high solar-hydrogen (STH) efficiency of 17.71 %, which has potential commercial applications. Also, Bi/In2S3up (S) and As/In2Te3up (As) exhibit desirable electrocatalytic HER performance. These insights provide an important strategy for application of ferroelectric heterojunctions in water splitting.

He+ beam irradiation boosting electrocatalytic performance of NiS2 nanosheets for hydrogen evolution reaction

Hydrogen evolution by water splitting is one of the most popular methods in the new generation energy exploration. During the hydrogen evolution reaction (HER), NiS2, which is an electrochemical catalyst, has been widely investigated. However, the electrochemical catalytic performance of NiS2-based catalysts is still dissatisfied due to their relatively poor intrinsic catalytic activities. Herein, we introduced vacancies into NiS2 nanosheets and the activation of initial inert sulfur sites by He+ ion irradiation (at a dose of 1 × 1015/cm2) to improve the HER electrocatalytic performance of NiS2. Additionally, density functional theory (DFT) calculations were adopted. Clearly, the intrinsic vacancies (both Ni and S vacancies) of NiS2 can reduce the band gap of NiS2 and improve its electron transfer efficiency in the HER process. This work provides a candidate strategy for NiS2-based electrocatalysts to optimize HER performance.

Modulating the electronic structure at the interface of CoSe and MoSe2 for enhanced electrocatalytic hydrogen evolution reaction

Metal selenide is a group of promising electrocatalysts for hydrogen evolution reaction (HER). However, Molybdenum selenide (MoSe2) exhibits sluggish HER kinetics in alkaline electrolytes mainly due to inherently inferior electrical conductivity and disappearance of edge active sites. Herein, we reported the preparation of MOF-derived CoSe/MoSe2 heterogeneous structure with excellent electrocatalytic activity in HER. The overpotential of CoSe/MoSe2 at current density of 10 mA cm−2 was only 135 mV. DFT calculations and characterization results revealed that the excellent HER electrocatalytic performance was attributed to the fabrication of the CoSe/MoSe2 interface. As-fabricated interface not only improved the electrical conductivity through modulating the electronic structure, but also enhanced H∗ adsorption thereby alleviating the energy barrier. Moreover, CoSe derived from the ZIF-67 with porous structure can provide the larger surface for the uniform growth of MoSe2 and then expose abundant edge active sites of MoSe2. This work enriched and developed the strategies for the designing of more highly efficient electrocatalysts via the heterogeneous interface modulation.

Direct Electrosynthesis of Metal Nanoparticles on Ti3C2Tx-Mxene during Hydrogen Evolution.

Herein, we propose a simple yet effective method to deposit metal nanoparticles on Ti3C2Tx-MXene via direct electrosynthesis. Without using any reducing reagent or annealing under reducing atmosphere, it allows the conversion of metal salts (e.g., PtCl4, RuCl3·yH2O, IrCl3·zH2O, AgNO3, and CuCl2·2H2O) to metal nanoparticles with a small particle size (ca. 2 nm). Under these circumstances, it was realized that the support effect from Ti3C2Tx-MXene (electron pushing) is quite profound, in which the Ti3C2Tx-MXene support will act as an electron donor to push the electron to Pt nanoparticles and increase the electron density of Pt nanoparticles. It populates the antibonding state of Pt-Pt bonds as well as the adsorbate level that leads to a "weakening" of the ΔGH* in the optimal position. This rationalizes the outstanding activity of Pt/Ti3C2Tx-MXene (5 wt %, η10 = 16 mV) for the hydrogen evolution reaction (HER). In addition, this direct electrosynthesis method grants the growth of two or multiple types of metal nanoparticles on the Ti3C2Tx-MXene substrate that can perform dual or multiple functions as desired. For instance, one can prepare an electrocatalyst with Pt (2.5 wt %) and Ru nanoparticles (2.5 wt %) on the Ti3C2Tx-MXene support from the same synthetic method. This electrocatalyst (Pt_Ru/Ti3C2Tx-MXene) can display good electrocatalytic HER performance in both acid (0.5 M H2SO4) and alkaline electrolytes (1.0 M KOH).

Engineering Double Sulfur-Vacancy in CoS1.097@MoS2 Core-Shell Heterojunctions for Hydrogen Evolution in a Wide pH Range.

Heterostructured nanomaterials have arisen as electrocatalysts with great potential for hydrogen evolution reaction (HER), considering their superiority in integrating different active components but are plagued by their insufficient active site density in a wide pH range. In this report, double sulfur-vacancy-decorated CoS1.097@MoS2 core-shell heterojunctions are designed, which contain a primary structure of hollow CoS1.097 nanocubes and a secondary structure of ultrathin MoS2 nanosheets. Taking advantage of the core-shell type heterointerfaces and double sulfur-vacancy, the CoS1.097@MoS2 catalyst exhibits pH-universal HER performance, achieving the overpotentials at 10 mA cm-2 of 190, 139, and 220 mV in 0.5 M H2SO4, 1.0 M KOH, and 1.0 M PBS, respectively. Systematic theoretical results show that the double sulfur-vacancy can endow the CoS1.097@MoS2 core-shell heterojunctions with promoted electron/mass transfer and enhanced reactive kinetics, thus boosting HER performance. This work clearly demonstrates an indispensable role of double sulfur-vacancy in enhancing the electrocatalytic HER performance of core-shell type heterojunctions under a wide pH operating condition.

Optimization of the in-plane activity of MoS2 monolayer by Pd-S bonds for hydrogen evolution reaction

Simulate to hydrogenase, 2D molybdenum disulfide (MoS2) as a typical member among transition metal dichalcogenides have received extensive attentions for hydrogen evolution reaction (HER). However, it is found that the exposure plane of 2D MoS2 is inert to HER whereas the edge sites are more active. Herein, Pd doping strategy is applied to significantly enhance the in-plane activity of MoS2 monolayer, and the structure–activity relationship is studied in detail. The centimeter-scale monolayer Pd-MoS2 films with Pd-S bonds were prepared. For the Pd-MoS2 with 7.4 at% Pd amount, the overpotential of HER decreases to 163 mV (vs. RHE) at 5 mA cm−2 and 205 mV (vs. RHE) at 10 mA cm−2. DFT calculations reveal that the ΔGH* is dramatically reduced to −0.12 eV at the S site adjacent to Pd atom in 2H Pd-MoS2. Moreover, the charge transfer efficiency significantly increases with increasing the Pd dopant amount for the Pd-MoS2 when compared to the MoS2. This work provides insights into the structure modification of 2D MoS2 for tuning the electrocatalytic HER performance.

Regulating the tip effect on urchin-like N-NiCoP/NF as high-performance electrocatalyst for hydrogen evolution reaction

Transition metal phosphides (TMPs) have emerged as highly promising electrocatalysts for the hydrogen evolution reaction (HER) due to their earth-abundance reserves, rich electrochemical active sites and high stability. Herein, to cope with the inert atoms on the basal plane and sluggish electrochemical kinetics, we propose a novel strategy involving the in-situ conversion of urchin-like NiCo-LDH into a nitrogen-doped NiCoP electrocatalyst on nickel foam (N-NiCoP/NF) via a hydrothermal-phosphorylation approach. In this structure, NiCoP nanoneedles are assembled into a tip-rich urchin-like structure on NF substrates, delivering abundant mismatched active sites for capturing catalytic intermediates, accelerating charge transport and constructing an optimized heterogeneous interface. Additionally, heterogeneous N-atom doping can further regulate the charge distribution of NiCoP needles, and significantly contribute to enhancing the electrocatalytic performance for HER. Benefitting from the synergistic effect of the abundant active sites provided by tip-rich NiCoP nano-urchin, electronic modulation by heterogeneous N-species and optimized interfacial coupling, the N-NiCoP/NF electrocatalyst displays low overpotentials of 75 mV and obtains 10 mA cm−2 in alkaline electrolyte without significant decrease even after 5000 cycles, indicating high catalytic activity and stability. This study provides a low-cost and controlled approach for developing novel heteroatom-doped TMPs for HER applications.The various properties of the materials surprisingly demonstrate that our diatomic codoping strategy prepared by facile hydrothermal phosphatization with annealing can effectively enhance the HER properties of the materials. The unique morphology possessed by the material provides advantages such as active sites and accelerated charge transport that can further enhance the catalytic performance of the material, which is further formalized by our DFT calculations. Our theoretical and experimental studies provide a good case for the development of simple and low-cost electrocatalytic materials.

Co-Ru alloy nanoparticles decorated onto two-dimensional nitrogen doped carbon nanosheets towards hydrogen/oxygen evolution reaction and oxygen reduction reaction

Constructing highly-efficient electrocatalysts toward hydrogen evolution reaction (HER)/oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) with excellent stability is quite important for the development of renewable energy-related applications. Herein, Co-Ru based compounds supported on nitrogen doped two-dimensional (2D) carbon nanosheets (NCN) are developed via one step pyrolysis procedure (Co-Ru/NCN) for HER/ORR and following low-temperature oxidation process (Co-Ru@RuOx/NCN) for OER. The specific 2D morphology guarantees abundant active sites exposure. Furthermore, the synergistic effects arising from the interaction between Co and Ru are crucial in enhancing the catalytic performance. Thus, the resulting Co-Ru/NCN shows remarkable electrocatalytic performance for HER (70 mV at 10 mA cm−2) in 1 M KOH and ORR (half-wave potential E1/2 = 0.81 V) in 0.1 M KOH. Especially, the Co-Ru@RuOx/NCN obtained by oxidation exhibits splendid OER performance in both acid (230 mV at 10 mA cm−2) and alkaline media (270 mV at 10 mA cm−2) coupled with excellent stability. Consequently, the fabricated two-electrode water-splitting device exhibits excellent performance in both acidic and alkaline environments. This research provides a promising avenue for the advancement of multifunctional nanomaterials.

Facile synthesis of flower-like MoSxSe2-x nanocomposites for efficient hydrogen evolution

To solve the poor conductivity and limited active sites of MoSe2, ternary MoSxSe2-x nanosheets with defects were synthesized by a convenient hydrothermal process. The results showed that the introduction of S element not only improved the electron transfer ability, but also provided more electrocatalytic active sites. Consequently, the optimized MoSxSe2-x with a S/Se molar ratio of 1:1 (MoSSe) presented superior electrocatalytic hydrogen evolution reaction performance with a low Tafel slope of 47 mV/dec, and a small overpotential of −165 mV at −10 mA/cm2 as well as good durability. This work provides an additional route for better understanding the modulation of multi-factors in designing and synthesizing MoSe2-based catalysts to improve their electrochemical activity.

Keplerate polyoxomolybdate nanoball mediated controllable preparation of metal-doped molybdenum disulfide for electrocatalytic hydrogen evolution in acidic and alkaline media

Rationally designed novel cost-effective hydrogen evolution reaction (HER) electrocatalysts with controlled surface composition and advanced structural superiority is extremely critical to optimize the HER performance. Polyoxometalates (POMs) with structural diversity and adjustable element compositions represent a promising precursor for rational design and preparation of HER electrocatalysts. Herein, a series of transition metal-doped MoS2 materials with different surface engineered structures (Fe, Cr, V doping and S vacancies) (M-MoS2/CC, M = Fe, Cr and V) were fabricated by a simple hydrothermal-vulcanization strategy using Keplerate polyoxomolybdate nanoball ({Mo72Fe30}, {Mo72Cr30}, {Mo72V30}, {Mo132}) as precursors. The enlarged interlayer spacing as well as the integration of homogeneous transition metal doping and abundant sulfur vacancies endows prepared M-MoS2/CC with superior HER electrocatalytic performance and excellent long-term working stability in both acidic and alkaline media. The optimized Fe-MoS2/CC afford current densities of 10 and 50 mA/cm2 at overpotentials of 188/272 mV and 194/394 mV in 0.5 mol/L H2SO4 and 1.0 mol/L KOH aqueous solution, respectively, outperforming most of reported typical transition metal sulfide-based catalysts. This work represents an important breakthrough for POMs-mediated highly efficient transition metal sulfide-based HER electrocatalysts with wide range pH activity and may provide new options for the rational design of promising HER electrocatalysts and beyond.