Hydrogen evolution reaction on in-plane platinum and palladium dichalcogenides via single-atom doping

Searching for the catalysts with excellent catalytic activity and high chemical stability is the key to achieve large-scale production of hydrogen (H₂) through hydrogen evolution reaction (HER). Two-dimensional (2D) platinum and palladium dichalcogenides with extraordinary electrical properties have emerged as the potential candidate for HER catalysts. Here, chemical stability, HER electrocatalytic activity, and the origin of improved HER performance of Pt/Pd-based dichalcogenides with single-atom doping (B, C, N, P, Au, Ag, Cu, Co, Fe, Ni, Zn) and vacancies are explored by first-principles calculations. The calculated defect formation energy reveals that most defective structures are thermodynamically stable. Hydrogen evolution performance on basal plane is obviously improved by single-atoms doping and vacancies. Particularly, Zn-doped and Te vacancy PtTe₂ have a ΔG_H value close to zero. Moreover, defect engineering displays a different performance on HER catalytic activity in sulfur group elements, in order of S < Te < Se in Pd-based chalcogenides, and S < Se < Te in Pt-based chalcogenides. The origin of improved hydrogen evolution performance is revealed by electronic structure and charge transfer. Our findings of the highly activating defective systems provide a theoretical basis for HER applications of platinum and palladium dichalcogenides.     

Two-dimensional B7P2: Dual-purpose functional material for hydrogen evolution reaction/hydrogen storage

It is well known that the development of dual-purpose materials is more significant and valuable than single-use materials due to the diversity of their use purposes. Based on density functional theory (DFT), the hydrogen evolution/hydrogen storage characteristics of two-dimensional (2D) B₇P₂ monolayer are systematically studied in this paper, focusing on the key word of clean energy-“hydrogen”. The results show that the B₇P₂ monolayer can be used as a stable metal-free decorated catalyst for hydrogen evolution reaction (HER), which is renewable and environmentally friendly. The calculated Gibbs free energy (ΔG_H1) is 0.06 eV, which is comparable or even better than that of Pt catalyst (ΔG_H1 = ?0.09 eV). In addition, we also found that the increase of hydrogen coverage and strain driving (?2%–2%) did not further enhance the HER activity of B₇P₂ monolayer, showing a poor ΔG_H1. In the aspect of hydrogen storage, we have investigated the hydrogen storage performances of alkali-metal (Li, Na and K) doped B₇P₂. It is found that in the fully loaded case, B₇P₂Li₆ is a promising hydrogen storage material with a 7.5 wt% H₂ content and 0.15 eV/H₂ average hydrogen adsorption energy (E_ave). Moreover, ab initio molecular dynamics (AIMD) calculations show that there is no dynamic barrier for H₂ desorption of Li-decorated B₇P₂ monolayer. In conclusion, our results indicate that the B₇P₂ monolayer is not only an excellent catalyst for HER, but also a promising hydrogen storage medium.     

Doping engineering: Highly improving hydrogen evolution reaction performance of monolayer SnSe

By using the first-principles approach, we explore the hydrogen evolution reaction (HER) performance of SnSe monolayer. It is found that the SnSe monolayer with or without intrinsic defects is not good HER catalyst. By doping eighteen different elements at Sn or Se sites of the SnSe monolayer, we find that the elements P and In can effectively reduce the free energies of hydrogen (H) adsorption (ΔG) to −0.1 eV and 0.21 eV, much lower than 1.45 eV of perfect monolayer SnSe. This is attributed to great dispersion of electronic density of states of absorbed hydrogen atom having small interactions with doping elements. However, strong hybridizations between H and doping elements (K and Te) increase the ΔG values of doping systems (ΔG = 2.84 eV and ΔG = 1.77 eV).     

Metal-nonmetal atom co-doping engineered transition metal disulfide for highly efficient hydrogen evolution reaction

The development of effective and non-precious electrocatalyts for hydrogen evolution reaction (HER) has attracted massive research interests. Herein, we report a density functional theory (DFT) investigation on the activation and optimization of Molybdenum disulfide (MoS₂) monolayer as efficient HER electrocatalysts by cobalt-nonmetal atom (X = B, C, N, P, Se) codoping. Our results show that three CoX-MoS₂ (X = C, N, and Se) catalysts display enhanced HER performance with |ΔG_H|s in the range of 0.12–0.23 eV. Careful electronic structure analysis manifests that the favorable H adsorption process on the MoS₂ basal plane is induced by suitable in-gap states upon codoping. Furthermore, appropriate biaxial strain can help optimize the HER performance of these co-doped systems, e.g, the ΔG_Hs of CoC@MoS₂, CoN@MoS₂, and CoSe@MoS₂ reaches 0.0 eV, ?0.04 eV, and ?0.01 eV at 1.86% tensile strain, 5% compressive strain, and 4% compressive strain, respectively. Our work offers a highly promising catalyst for HER and guides the atomic design of more efficient non-noble electrocatalysts.     

High-throughput screening of transition metal single-atom catalyst anchored on Janus MoSSe basal plane for hydrogen evolution reaction

Considerable efforts have been made to enhance the hydrogen evolution reaction (HER) catalytic performance of Janus MoSSe monolayer, which have been considered to be a promising candidate due to the unique asymmetry structure. However, the activation effect remains non-optimal for the inert Janus MoSSe basal plane at present. Herein, a train of transition metal (TM) atoms were anchored on the S-/Se-/Mo-defective MoSSe basal plane to screen effective TM single-atom catalysts for HER through density functional theory (DFT) computations. Interestingly, the single Co atom anchored on Mo-defective MoSSe and the single Zn or Cd atom anchored on S-defective MoSSe were judged to possess excellent HER performance yielding a near-zero ΔG_H (ΔG_H = ?0.050, ?0.095, ?0.098 eV, respectively), which is comparable to the optimized Pt-SACs. The enhanced HER activity is attributed to the doping of TM atoms (Co, Zn and Cd) which improves the conductivity of the original MoSSe and offers unoccupied states near the Fermi level decreasing the energy barrier of electrons transfer between H and TMs@MoSSe surface. In addition, the change of unoccupied antibonding states of active atoms leads to appropriate interaction between the active sites and H. The hybridization between H-s orbital and the TMs@MoSSe systems around the Fermi level also suggests the formation of stable bonding-antibonding hydrogen adsorption states. This work reveals an effective way of activating MoSSe basal plane for HER.     

Mechanistic insights into hydrogen evolution reaction on Ni2B(001) facet using first-principle calculations

In this paper, first-principle calculations based on density functional theory (DFT) were used to investigate the performance and mechanism of the hydrogen evolution reaction (HER) on the typical active (001) facet of the novel electrocatalyst Ni₂B. There were two types of atomic distribution on the Ni₂B (001) surface, namely the B-rich surface and the Ni-rich surface. The investigation of the reaction mechanism revealed that the Volmer-Heyrovsky mechanism was easier to be realized on this Ni₂B (001) facet, and the Heyrovsky reaction was the reaction rate-determining step. The Gibbs free energy(ΔG_H) on the B-rich surface was - 0.02 eV, which was closer to 0 eV than that on the Ni-rich surface of Ni₂B (001). The HER reactivity on the Ni-rich surface was increased by Cr-doping (ΔG_H = - 0.01 eV), which indicated that the introduction of other transition metal atoms might effectively increase the HER electrocatalysis activity of Ni₂B (001) surface. This work paves a new avenue for exploring efficient and durable non-precious metal electrocatalysts for HER in acidic medium.     

Engineering the semiconducting CdS nanostructures by N-doped rGO for enhancing the adsorption sites: Promising electrocatalyst for hydrogen evolution reaction

The development of non-noble electrocatalysts for hydrogen production from water is of immense interest as it is clean and eco-friendly. The present work explores the electrocatalytic performance of morphologically varied CdS NPs synthesized using different sulphur source and ionic liquids via hydrothermal treatment, in catalyzing hydrogen evolution reaction (HER). The hierarchical flower shaped morphology denoted as CdS–N3 outperformed other prepared electrocatalysts with a Tafel slope value of 118 mV dec^?1 and a low overpotential 344 mV @ a current density of 10 mA/cm². However, the outperformed CdS–N3 catalyst when blended with N doped rGO, it showed a superior activity with a low overpotential of 201 mV at 10 mA/cm². The catalyst disclosed a small Tafel slope of 70 mV dec^?1 corroborating that the catalyst contains more electroactive sites and oxygen vacancy voids for the adsorption-desorption of charge carriers generated from the heteroatom doping. The CdS/N-rGO catalyst also revealed a higher TOF value of 5.18 × 10^?3 s^?1, which further proves that catalyst is more efficient in releasing H₂ molecules and this findings affirms that CdS/N-rGO catalyst can be an efficient candidate for initiating HER kinetics with endurable stability in acidic medium for high purity hydrogen production.     

A platinum modulated tungsten oxide on Ag nanowires network as an indicator for in-situ visualized evaluation of the hydrogen evolution performance

The development of the real-time evaluation for the catalytic hydrogen evolution performance under a simple and convinient condiction is urgently needed, but still a great challenge. Herein, a platinum modulated WO_x on Ag nanowires (Pt-WO_x@Ag NWs) is developed as an optical-electrochemical catalyst to realize an in-situ intuitive evaluation for the hydrogen evolution performance, in which the color of as-prepared Pt-WO_x@Ag NWs catalyst changes from the transparent to the deep blue with the increase of the applied potential. The real-time H₂ evolution with an H₂ turnover frequency (from 0 to 2.26 s^?1 per site), optical transmittance (from 80.3% to 48.7% at the wavelength of 630 nm) and energy consumption (from 0 to 0.74 W h in 1 h) is established. The charge transfer and mass transport are greatly promoted by the three demensional Ag NWs conductive network and abundant active sites, which are provided by the platinum modulated WO₃ on the Ag substrate. Density functional theory (DFT) calculations indicate that the modified WO_x shows the preferred adsorption affinity toward H₂O (ΔG_H2O, ?0.17 eV), which reach a high coloration efficiency and optical modulation range for the electrochromic reaction. The Pt sites on WO_x with a suitable H binding energy (ΔG_H1, 0.38 eV) efficiently promote the H1 conversion and H₂ release of water splitting. This work propose an intelligent hydrogen evolution indicator by real-time color change to boost the high-quality development of green hydrogen energy.     

Platinum doped iron carbide for the hydrogen evolution reaction: The effects of charge transfer and magnetic moment by first-principles approach

In this work, the catalytic activity towards hydrogen evolution reaction (HER) was studied for hydrogen adsorption on Pt doped Fe₂C (001) surface configuration (Pt/Fe₂C) and compared with pure Pt (001). The adsorption of H on the pristine Fe₂C, Pt doped Fe₂C, and pure Pt in (001) slab was computed. The best and promising HER activity (ΔG_H1 = −0.02 eV) is obtained at the hollow site adsorption of Pt/Fe₂C (Fe₁₃Pt₃C₈) compared to the experimental value of pure Pt (ΔG_H1 = −0.09 eV) suggesting the possibility of the H₂ formation on the surface of Fe₁₃Pt₃C₈. The structural stabilities of Fe₂C and Pt/Fe₂C were investigated by the formation energy analysis. Also, it is observed that to enhance the HER mechanism, the modification of the d-electron structure of Pt atoms is essential which can be achieved by the increased Pt doping. The Bader charge analysis demonstrated the charge transfer between the substrate and the adsorbed H atoms. The density of states (DOS) of pure Fe₂C and optimal Pt/Fe₂C were calculated which revealed the magnetic and metallic nature of these materials. In addition, the adsorption and resulted activation of H₂ were facilitated by the elongation of H–H bond length in Fe₁₃Pt₃C_8. This work supports the HER over single atom catalysts (SACs) with lower Pt loading but with high catalytic activity and the maximum atom utilization of SACs.     

Enhanced hydrogen evolution reaction performance of MoS2 by dual metal atoms doping

Molybdenum disulfide (MoS₂) has been considered a promising high-efficiency, low-cost hydrogen evolution reaction (HER) catalyst in acidic and alkaline media. However, the lack of active sites in the basal plane become the most significant obstacle hindering the widespread application of MoS₂. Here, we systematically studied the HER performance of MoS₂ plane or edge by co-doping Co atom and other 3d transition metals (TM = Ti–Fe, Ni) by density functional theory calculation methods. Interestingly, the dual atoms doping in both the basal plane and edges of MoS₂ is a feasible fabrication with small or negative formation energies. Compared with the pristine MoS₂ electrocatalyst, the HER performance in these doped systems is largely enhanced in both basal plane and edges due to the effective charge regulation on the S site by dual atom doping. Remarkably, close to zero H adsorption free energy (ΔG_H = ?0.161–0.119 eV) is identified for the TM-Co co-doped MoS₂ basal, indicating that they are potential alternate HER electrocatalysts of Pt. Our study provides a new strategy to design highly efficient non-noble metal electrocatalysts accessibility for energy-related applications.     

Modulation of the B4N monolayer as an efficient electrocatalyst for hydrogen evolution reaction

Exploring stable catalysts with an efficient hydrogen evolution reaction (HER) arises intense concerns due to its renewable and low-cost properties. In this work, we have systematically investigated a two-dimensional (2D) material, namely, B₄N monolayer as efficient HER electrocatalysts based on first-principles computations. When the material is metal-free, the calculated Gibbs free energy (ΔG_H1) corresponding to hydrogen coverages of 2/4 reaches to 0.005 eV, which is better than that of the Pt catalyst. Moreover, we also find that the HER activity of the B₄N monolayer is sensitive to the strains-driven. The single metal atom supported on B₄N can still make the value of ΔG_H1 close to 0 eV for Cr/B₄N and V/B₄N. These results reveal that the B₄N monolayer is a promising candidate for HER applications.     

Transition metal atoms anchored 2D holey graphyne for hydrogen evolution reaction: Acumen from DFT simulation

Here, we report a theoretical design of transition metals (TMs) anchored two-dimensional (2D) holey graphyne (HGY) based catalyst for the hydrogen evolution reaction (HER) through state-of-art density functional theory (DFT) simulation. The studied TMs (Co, Fe, Cr) are bonded strongly on HGY surface due to charge transfer from d orbital of metal to C 2p orbital of HGY. The HGY+TMs systems are stable at room temperature as evident from ab-initio molecular dynamics (AIMD) simulation. We predicted that the Co, Fe and Cr anchored HGY are highly active for HER activity with Gibbs free energy (ΔG) value as low as −0.21, −0.14, and −0.05 eV respectively and which are close to the best-known HER catalyst (Pt metal). The enhanced HER performance is attributed to the increased conductivity as well as redistribution of electrons. As pristine HGY is experimentally synthesized, HGY+TMs (Co, Fe, Cr) systems can be as an efficient catalyst for H₂ production.     

Accelerate the alkaline hydrogen evolution reaction of the heterostructural Ni2P@Ni(OH)2/NF by dispersing a trifle of Ru on the surface

Electrocatalytic water splitting for hydrogen production plays a vital role in the development of new energy field, but there is still a lack of low-content precious metal or cost-effective non-noble metal catalysts for the hydrogen evolution reaction (HER). Therefore, how to develop the catalysts with a smaller amount of precious metal to achieve higher performance is still a major challenge. Herein, we have fabricated Ru–Ni₂P@Ni(OH)₂/NF-2 heterostructure by phosphating Ni(OH)₂/NF and then anchoring Ru on the surface through wet chemical strategy. Benefiting from its optimal ΔG_H1 and synergistic effect, this Ru–Ni₂P@Ni(OH)₂/NF-2 catalyst shows superior electrocatalytic HER kinetics in alkaline electrolyte. A small overpotential of 31 mV is needed for this electrocatalyst to obtain the current densities of 10 mA cm^?2 with remarkable durability over 24 h. This work provides a new strategy for the preparation of effective HER electrocatalyst with a low precious metal content.     

Theoretical study of single-nonmetal-modified V2CO2 MXene as an efficient electrocatalyst for overall water splitting

The electrocatalytic water splitting consists of two half-reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which require low-cost and highly activity catalysts. Two-dimensional transition metal carbon-nitride (MXenes) are considered as the potential catalysts candidates for HER and OER due to their unique physical and chemical properties. In this work, using density functional theory (DFT), we have investigated the effect of single non-metal (NM, NM = B, N, P, and S) atoms doping, strain, and terminal types on the HER and OER activities of V₂CO₂ MXene. Results indicated that P doping V₂CO₂ (P/V₂CO₂) has best HER performance at hydrogen coverage of θ = 1/8, and N doping V₂CO₂ (N/V₂CO₂) has best OER performance among the studied systems. In addition, it can be found that there is a strong correlation between the ΔG_H and strain, ΔG_H and valence charges of the doped atoms after applying strain to the doping structures, with the correlation coefficient (R²) about equal 1. Moreover, the mixed terminal can enhance the performances of HER and OER, which obey the follow rules: mixed terminal (O1 and 1OH) > original terminal (O1) > 1OH terminal. The ab initio molecular dynamics simulations (AIMD) results revealed that the single non-metallic doped structures are stable and can be synthesized experimentally at different terminals.     

Tuning of electrocatalytic activity of mixed metal dichalcogenides supported NiMoP coatings for alkaline hydrogen evolution reaction

The mixed metal dichalcogenides combination of WS₂–MoS₂ was coated onto Cu substrate by electroless NiMoP plating technique and the electrocatalytic hydrogen evolution reaction (HER) performance was investigated. The enhanced structural, morphological parameters and boosted electrocatalytic performance of the various metal-metal molar ratio of WS₂–MoS₂ onto NiMoP plate were identified under variable operating conditions and it was successfully evaluated by various characterization techniques. The well-defined crystalline nature, phase, particle size, structure, elemental analysis and surface morphology of prepared coatings were analyzed by FESEM, XRD, AFM and EDS mapping. The electrochemical analysis was performed using open circuit potential (OCP) analysis, chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), Tafel curves, linear sweep voltammetry (LSV), cyclic voltammetry (CV) and polarization studies to find the activity of prepared electrocatalyst towards electrochemical hydrogen evolution reactions. The performance of bare NiMoP and WS₂–MoS₂/NiMoP plates were compared and found that the HER activity of NiMoP can be reinforced by composite incorporation through the synergic effect arises with in the catalytic system, which improves surface roughness and enhances the magnitude of electrocatalyst toward HER. The achievement of enhanced catalytic performance of coatings was authenticate by the kinetic parameters such as decreases in Tafel slope (98 mV dec^?1), enhanced exchange current densities (9.32 × 10^?4 A cm^?2), and a lower overpotential. The consistent performance and durability of the catalyst were also investigated. The enhanced electrocatalytic activity of WS₂–MoS₂/NiMoP coatings increased with respect to the surface-active sites associated with combination of mixed dichalcogenides and the synergic effect arises in between different components present in the coating system. This work envisages the progressive strategies for the economical exploration of a novel WS₂–MoS₂/NiMoP water splitting catalyst used for large scale H₂ generation. The prepared WS₂–MoS₂/NiMoP embedded Cu substrate possess high catalytic activity due to its least overpotential of 101 mV at a benchmark current density of 10 mA cm^?2, which demonstrated the sustainable, efficient and promising electrocatalytic property of prepared catalyst towards HER under alkaline conditions.     

Hydrothermal preparation of MoX2 (X = S,Se, Te)/TaS2 hybrid materials on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction

The prominent features-based two-dimensional (2D) materials have proven themselves as efficient as well as robust electrocatalysts for the hydrogen evolution reaction (HER) owing to their low-cost, abundance and predominant conductivity. In this work, we report the synthesis of series of molybdenum chalcogenide nanostructures MoX₂ (X = S, Se, Te), hybridized with TaS₂ nanosheets, via a facile hydrothermal method, on self-supported carbon cloth electrode. Used as an electrocatalyst for HER, hybrid phase MoSe₂/TaS₂/CC electrode with a Mo/Se ratio of 1:1.5 exhibits the best HER performance, which could afford the benchmark current densities of 10 mA/cm² at the overpotentials of 75 mV with the measured Tafel slope values of 54.7 mV/dec. In addition, the presented molybdenum dichalcogenides in this work are also complimented with robustness as determined from durability and air stability measurements. The unique aspects of these unique hybrids, such as 1T and 2H phases hybridized MoS₂ and MoSe₂, semimetallic nature 1T′-MoTe₂ petal clusters and strong interface interaction between MoX₂ (X = S, Se, Te) and conductive TaS₂ nanosheets, cause superior HER catalytic performance.     

Phase controlled synthesis and the phase dependent photo-and electrocatalysis of CdS@CoMo2S4/MoS2 catalyst for HER

Herein we report a heterostructure with ultrathin nanosheets of Co-doped molybdenum sulfide on CdS nanorod array (donated as CdS@CoMo₂S₄/MoS₂) by hydrothermal synthesis. Firstly, elemental Co doping MoS₂ (CoMo₂S₄) delivers the double benefits of increased active sites and enhanced conductivity. Secondly, the structural characteristics maximally exposes the MoS₂ edges and enlarges interfacial contact area between the composite catalyst and electrolyte, as well as the efficient interfacial charge transfer. The ratio of CoMo₂S₄/MoS₂ in CdS@CoMo₂S₄/MoS₂ plays a crucial role for the enhanced photo-assistant electrocatalytic hydrogen evolution reaction (HER). We can tune the ratio of CoMo₂S₄/MoS₂ by controlling the preparation time or the ratio of precursor of Co/Mo. The catalyst with predominant MoS₂ phase shows superior photocatalytic HER performance with a high H₂ production rate of 46.60 μmol mg⁻¹ h⁻¹. Meanwhile, the catalyst with predominant CoMo₂S₄ phase exhibits not only relatively low overpotential of 172 mV at 10 mA cm⁻², which outperforms most values that have been reported on catalyst supported on ITO substrate, but also possesses H₂ production rate of 23.47 μmol mg⁻¹ h⁻¹. The superior photo-assistant electrocatalytic HER activity results from the synergistically structural and electronic modulations, as well as the proper energy band alignment between MoS₂ and CdS. This investigation could provide an approach to integrate the electro- and photocatalytic activities for HER, especially the photo responding behaviour at a bias potential which is meaningful to produce H₂ for actual application.     

Investigating hydrogen evolution reaction properties of a new honeycomb 2D AlC

The hydrogen due to its high mass energy density is a new renewable, economically viable and clean resource. The most eco-friendly and economical approaches for the generation of hydrogen through hydrogen evolution is electrochemical water splitting. The two-dimensional (2D) nanomaterials have been recently found as potential candidates as non-noble metal catalyst for hydrogen evolution. In this work, we have systematically studied the structural and electronic properties of the newly predicted hexagonal-aluminium carbide monolayer (h-AlC ML) under the framework of dispersion-corrected density functional theory (DFT) calculations. The calculated electronic total density of states (TDOS) of h-AlC ML predict its metallic nature in contrast to other polar honeycomb 2D materials which are either semiconducting or semimetallic. The metallic behavior of h-AlC monolayer which motivates us to investigate its HER activity results due to the presence of delocalized charge density near Fermi level. Thus, we have investigated the HER activity of h-AlC ML by calculating hydrogen (H) adsorption energy (ΔE_H) and Gibbs free energy (ΔG_H) at three different sites of the 3 × 3 and 4 × 4 supercells of h-AlC ML; top of carbon atom (E_H-C), top of aluminium atom (E_H-Al) and hollow site (E_H-Hollow). Our results show that the hollow site is most catalytically active site in both supercells of h-AlC ML. We believe that our results will inspire experimentalists to fabricate this new 2D material for achieving the desired range of HER activity.     

Greatly improved HER electrocatalytic activity by the composite of CoSe2 and N,S-dual doped graphitic carbon

Several composite catalysts were facilely fabricated by hydrothermal supporting CoSe₂ on N, S dual-doped graphitic mesoporous carbon (SDGC) synthesized by pyrolyzing thiocarbamide and in-situ formed phenolic resin. The synthesized CoSe₂/SDGC composites were characterized to have mesoporous structure distributed on the carbon matrix covered with the sphere like aggregates of CoSe₂. Their electrocatalytic performances were evaluated by hydrogen evolution reaction (HER) in 0.5 M H₂SO₄. The results have shown that the as-prepared catalysts exhibited highly improved electrocatalytic activities for HER compared with the pristine CoSe₂ and SDGC. Especially, the composite CoSe₂/SDGC-60 with the optimized ratio of CoSe₂ to SDGC has exhibited the highest electrocatalytic activity. The catalyst has obtained the lowest overpotential and Tafel slope of 203 mV (at 10 mA/cm²) and 58 mV/dec, respectively. It also showed impressive durability against 0.5 M H₂SO₄ and the electrocatalytic activity hardly decreased even after 5000 cycles.     

The effect of annealing temperature,reaction time,and cobalt precursor on the structural properties and catalytic performance of CoS2 for hydrogen evolution reaction

In this study, cobalt disulfide (CoS₂) nanostructures are synthesized using a simple hydrothermal method. The effects of experimental parameters including cobalt precursor, reaction times, and reaction temperatures are investigated on the structure, morphology and electrocatalytic properties of CoS₂ for hydrogen evolution reaction (HER). The characterization of as-prepared catalysts is performed using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). The HER efficiency of the catalysts is examined using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) methods in 0.5 M H₂SO₄ solution. Furthermore, chronoamperometry (CA) is used for stability evaluation. The catalyst obtained from cobalt acetate precursor, within 24 h at 200 °C exhibits superior electrocatalytic activity with a low onset potential (139.3 mV), low overpotential (197.3 mV) at 10 mA. cm^?2 and a small Tafel slope of 29.9 mV dec^?1. This study is a step toward understanding the effect of experimental parameters of the hydrothermal method on HER performance and developing optimal design approaches for the synthesis of CoS₂ as a common electrocatalyst.