Efficient Catalyst For Hydrogen Evolution Reaction Research Articles

Superhydrophilic/superaerophobic amorphous Ni3S2/NiMoS electrocatalyst for enhanced hydrogen evolution

It is important to develop electrocatalysts that are cheap and have high activity for hydrogen evolution reaction (HER). In this work, Ni3S2/NiMoS with amorphous phase and unique candied-haws shaped nanoarray structure was successfully grown on nickel foam (Ni3S2/NiMoS/NF) as efficient HER catalyst. Combining Ni3S2 with NiMoS resulted in the extension of the heterointerfaces between the materials, which facilitated the HER process in alkaline medium. The amorphous Ni3S2/NiMoS with disordered atom arrangement provided abundant active sites. Also, the unique morphology of the catalytic electrode simultaneously enabled it exhibit superhydrophilicity and underwater superaerophobicity. It is beneficial for the sufficient diffusion of the electrolyte onto the catalyst surface and the fast departure of hydrogen bubbles from the surface. As a result, the activity of Ni3S2/NiMoS/NF was higher than that of Pt/C even at high current densities. It is very valuable for industrial applications that require high current density. The superior stability of Ni3S2/NiMoS/NF compared to Pt/C further demonstrated that this catalytic electrode has potential for industrial applications.

Chemical Vapor Deposition of Ru/RuSe2 Catalyst for Electrolytic Hydrogen Evolution Reaction

AbstractA one‐step synthesis of highly stable Ru/RuSe2 nanoparticles (NPs) on carbon paper is achieved using low temperature and pressure chemical vapor deposition (CVD), resulting in a heterointerface with multiple active sites for catalysis. The catalyst exhibits outstanding performance for the hydrogen evolution reaction (HER) in an alkaline solution, with low overpotentials and fast hydrogen adsorption and desorption kinetics. The Ru/RuSe2/C nanoparticle structure has the potential for large‐scale production and can be used as an efficient catalyst for HER.

Modulating the crystallinity of 1D MoO3 and its conversion to 2D MoS2 nanosheets for efficient hydrogen evolution reaction catalysts

Molybdenum sulfide (MoS2) has been identified as a promising and ample electrocatalyst for hydrogen evolution reaction (HER). Herein, we have synthesized 2D MoS2 from 1D Molybdenum oxide (MoO3) prepared via hydrothermal method and subsequent annealing. The HER of the prepared MoO3 and MoO3 annealed at temperature varying from 100 to 700 °C is evaluated by utilizing linear sweep voltammetry (LSV) in acidic electrolyte medium with MoO3@300 °C displaying the best overpotential at 229 mV vs RHE, respectively. The enhanced HER activity of MoO3 annealed at 300°C is attributed to its higher crystallinity. Further, the MoO3 annealed at 300 °C is converted to MoS2 exhibiting excellent HER performance with overpotential of 197 mV. The Tafel slope, electrochemical active surface area (ECSA) and turn over frequency (TOF) values of MoS2, MoO3, at different annealed temperatures have also been analysed in this work.

Nickel-nitride composite: An eco-friendly and efficient alternative to platinum for electrocatalytic hydrogen production

Water electrolysis using the hydrogen evolution reaction (HER) is a promising method for sustainable hydrogen production. Platinum-based catalysts have traditionally been the most efficient HER catalysts, but their scarcity and sluggish water dissociation limit their practical applications. Here we report on a novel superhydrophilic catalyst of nickel supported on nickel molybdenum nitride (Ni/Ni0.8Mo4.2N6) that outperforms platinum-based nanomaterials. Despite the low catalytic activity of Ni or Ni0.8Mo4.2N6 alone, their optimized composite exhibits exceptional HER activity, with respective 500% and 150% increases in the exchange current and turnover frequency compared to commercial Pt/C. Density of states calculations reveal a decrease in electron density of the supported nickel in Ni/Ni0.8Mo4.2N6, leading to a lower free energy of the HER. These findings demonstrate a powerful electron-engineering strategy for designing supported electrocatalysts with outstanding performance for the HER and related processes.

Cu@S-Co(OH)2 hybrid electrocatalysts with high performance for alkaline hydrogen evolution reaction

Transition metal hydroxides have superior oxygen evolution reaction (OER) activity but poor hydrogen evolution reaction (HER) performance, which greatly limits the water splitting for hydrogen production. Herein, copper modification of sulfur doped Co(OH)2 hybrid catalyst (Cu@S-Co(OH)2) was prepared by one-step of electrodeposition method which can serve as efficient hydrogen evolution reaction catalyst. In the presence of sulfur and copper, Cu@S-Co(OH)2 hybrid catalyst exhibits the best catalytic activity, showing ultralow overpotential of 42 mV at a current density of 10 mA cm−2. Compared with Co(OH)2, the overpotential is improved by nearly 100 mV as well as enhanced stability. In addition, the active site poison experiments proved that the active center is cobalt metal. Combined with the adsorption strength of the catalyst for OH and H species, it is considered that both S and Cu can enhance the adsorption of OH for Co(OH)2, while S is contributed to the adsorption of H, and Cu can promote the desorption of H. This work provides a facile method and new insight to enhance the HER activity for transitional metal hydroxides via metal and non-metallic elements co-modulation.

Constructing crystalline/amorphous interfaces in crystalline vanadium disulfide/amorphous molybdenum sulfide/reduced graphene oxide nanocomposites via a hydrothermal-plasma method toward efficient hydrogen evolution reaction

Developing earth-abundant, efficient and durable catalysts toward the hydrogen evolution reaction (HER) is critical for the large-scale deployment of sustainable hydrogen production from renewable energies. Transition metal dichalcogenides (TMDs) are promising candidates for the replacement of precious and state-of-the-art platinum-groups-metals, but their HER performance still needs improvement. Constructing crystalline/amorphous interfaces is effective in terms of creating abundant active sites for boosted catalytic activity. Therefore, in this study, defective crystalline vanadium disulfide/amorphous molybdenum sulfide/reduced graphene oxide (c-VS2/a-MoSx/RGO) nanocomposites are fabricated via a combined hydrothermal-plasma method. The HER performance of c-VS2/a-MoSx/RGO is optimized by tuning the plasma treatment duration and the amount of precursors, and the corresponding mechanisms were investigated by morphological and elemental analyses. Taking advantage of the high reactivity of low-temperature plasma, the strategy presented in this work is effective in terms of constructing crystalline/amorphous interfaces and introducing multiple defects, which creates abundant active sites and ultimately results in boosted HER performance. The optimal c-20VS2/a-40MoSx/RGO catalyst exhibited excellent HER activity (η@100 mA cm−2 = 193 mV and η@500 mA cm−2 = 244 mV) and good stability. This work provides a facile and effective strategy for promoting the HER performance of TMDs and sheds light on rationally designing efficient HER catalysts using earth-abundant elements.

Orbital hybridization manipulated by doped Cu+ in NbC for boosting hydrogen evolution

Surface adsorption behavior and electron transfer determine the catalytic activity in hydrogen evolution reaction (HER). However, the inevitable surface oxidation of NbC hinders electron transfer and hydrogen conversion. The surface adsorption behavior and electron transfer of NbC are optimized by doping Cu+ as well as modifying the orbital hybridizations. Benefiting from the introduced electron interaction of Cu+, the lower p-d hybridization between Nb and O reduces the Nb-O bond and affords the Cu-NbC thinner surface oxidation layer. The reduced surface oxidation degree favors electron transfer. Further, the electron orbital hybridization modulates the electron states and optimizes the hydrogen adsorption behavior of Cu-NbC for efficient hydrogen conversion. As the electrochemical results, the obtained Cu-NbC demands 271 mV to drive 10 mA cm−2, which is 50 times higher than that of NbC (only 0.2 mA cm−2 at the same overpotential). Hence, we believe the orbital hybridization manipulation strategy renders a valuable solution for designing efficient HER catalysts.

Synergistic Acid Hydrogen Evolution of Neighboring Pt Single Atoms and Clusters: Understanding Their Superior Activity and Mechanism.

The hydrogen evolution reaction (HER) involves two-step elementary reactions, providing an opportunity to establish dual-site synergistic catalysts. This work demonstrates carbon-supported Pt single atoms and clusters (Pt1+Cs-NPC) as an efficient catalyst for acidic HER, which exhibits an ultralow Tafel slope of 12.5 mV/dec and an overpotential of 24 mV at 10 mA/cm2 with an ultralow platinum content of 3.8 wt %. The Pt mass activity and turnover frequency (TOF) are 10.2 times and 5.4 times that of commercial Pt/C, respectively. The density functional theory (DFT) study shows that the Pt cluster regulates the electronic state structure of the adjacent Pt single atom, so that the ΔGH* at the Pt1 site approaches 0. Moreover, the DFT study confirms that Pt clusters and neighboring Pt single atoms can synergistically catalyze the Tafel step and reduce the energy barrier in forming the H-H bond. At the same time, the platinum cluster reduces the energy barrier of the nearby platinum single-atom site to the Heyrovsky step and accelerates the reaction with hydrated hydrogen ions. Studies have shown that platinum clusters and platinum single-atom composite loading structures exhibit excellent activity for the Volmer-Tafel or Volmer-Heyrovsky reaction paths of HER reactions. This work provides a clear understanding of the synergistic effect of Pt1+Cs-NPC, which provides guidance for developing efficient HER catalysts.

High-throughput screening of H2 production catalysts from doped In2SSe monolayer: Valence electrons-based descriptor

Recently, the novel Janus In2SSe monolayer attracts great attention as a potential catalyst for hydrogen evolution reaction (HER). In this work, high-throughput calculations are carried out to screen the numerous transition-metal-doped In2SSe monolayers for designing hydrogen production catalysts. A series of doped In2SSe monolayers have been screened out with comparable or even better catalytic activity than that of Pt (111). Particularly, The AuS@In2SSe possess the best catalytic performance with a hydrogen adsorption free energy of 0 eV. These results suggest that the catalytic activity is influenced by the local environment of the active center. In addition to the revised pz band center, the valence electrons of the dopants also have a highly linear relationship with the hydrogen adsorption free energy, which can be used as a new descriptor for screening efficient HER catalysts. Machine learning is used to reveal the intrinsic relationship between structure and catalytic performance. Our work offers a new perspective for the design of novel HER catalysts.

Interstitial Hydrogen Atom to Boost Intrinsic Catalytic Activity of Tungsten Oxide for Hydrogen Evolution Reaction.

Tungsten oxide (WO3 ) is an appealing electrocatalyst for the hydrogen evolution reaction (HER) owing to its cost-effectiveness and structural adjustability. However, the WO3 electrocatalyst displays undesirable intrinsic activity for the HER, which originates from the strong hydrogen adsorption energy. Herein, for effective defect engineering, a hydrogen atom inserted into the interstitial lattice site of tungsten oxide (H0.23 WO3 ) is proposed to enhance the catalytic activity by adjusting the surface electronic structure and weakening the hydrogen adsorption energy. Experimentally, the H0.23 WO3 electrocatalyst is successfully prepared on reduced graphene oxide. It exhibits significantly improved electrocatalytic activity for HER, with a low overpotential of 33mV to drive a current density of 10mA cm-2 and ultra-long catalytic stability at high-throughput hydrogen output (200 000 s, 90mA cm-2 ) in acidic media. Theoretically, density functional theory calculations indicate that strong interactions between interstitial hydrogen and lattice oxygen lower the electron density distributions of the d-orbitals of the active tungsten (W) centers to weaken the adsorption of hydrogen intermediates on W-sites, thereby sufficiently promoting fast desorption from the catalyst surface. This work enriches defect engineering to modulate the electron structure and provides a new pathway for the rational design of efficient catalysts for HER.

A descriptor of IB alloy catalysts for hydrogen evolution reaction

AbstractAlloying is regarded as one of the most promising strategies for boosting performance of catalysts for hydrogen evolution reaction (HER) due to the adjustable electronic structure and intermediate adsorption. However, there is no theory (including d‐band center theory) can accurately guide the preparation and design of alloy catalysts, and thus resulting all the reported alloy catalysts are obtained by time‐consuming and laborious experimental exploration. Herein, we proposed a mean d‐band center (εas) as a new accurate descriptor for alloy activity prediction. Theoretical simulation and experiment results revealed that this descriptor exhibits a strong scaling relation with H adsorption energy. Besides, the obtained Cu–Ag alloy displays an optimal overpotential of 223 mV at 10 mA/cm2 in 0.5 mol/L H2SO4, which is more than 300 mV lower than those of pristine Cu (530 mV) and Ag (569 mV) powder. Our work provides a new idea toward designing highly efficient HER catalysts and broadens the applicability of d‐band theory to activity prediction of alloys.

Unraveling the Role of Orbital Interaction in the Electrochemical HER of the Trimetallic AgAuCu Nanobowl Catalyst.

Unraveling the origins of the electrocatalytic activity of composite nanomaterials is crucial but inherently challenging. Here, we present a comprehensive investigation of the influence of different orbitals' interaction in the AuAgCu nanobowl model electrocatalyst during the hydrogen evolution reaction (HER). According to our theoretical study, AgAuCu exhibits a lower energy barrier than AgAu and AgCu bimetallic systems for the HER, suggesting that the trimetallic AgAuCu system interacts optimally with H*, resulting in the most efficient HER catalyst. As we delve deeper into the HER activity of AgAuCu, it was observed that the presence of Cu allows Au to adsorb the H* intermediate through the hybridization of s orbitals of hydrogen and s, dx2-y2, and dz2 orbitals of Au. Such orbital interaction was not present in the cases of AgAu and AgCu bimetallic systems, and as a result, these bimetallic systems exhibit lower HER activities.

Defect engineered Janus MoSiGeN4 as highly efficient electrocatalyst for hydrogen evolution reaction

It is well known that defect engineering is very important to the improvement of catalyst activity. In this paper, defect engineering is introduced into Janus MoSiGeN4 to regulate hydrogen evolution reaction (HER) activity. Based on density functional theory, a theoretical study is carried out to clarify the roles of vacancy and transition metal (TM) atom doping in Janus MoSiGeN4. Five different vacancies are considered, and results suggest that outmost N vacancy can effectively enhance the HER activities. For VN2@MoSiGeN4 and VN1@MoSiGeN4 structures, the hydrogen adsorption Gibbs free energy (ΔGH*) is 0.015 eV and 0.145 eV, respectively. Moreover, a systematic screening of eleven non-precious TM atoms (V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ta and W) doped MoSiGeN4 as HER catalysts reveals that Fe-, Mn-, and Nb-doped MoSiGeN4 show better HER activity than that of Pt with theΔGH* of 0.013 eV, 0.061 eV, and 0.087 eV, respectively. Electronic properties, electron charge density difference and Bader charge are employed to explore the origin of electrocatalytic activity. Our study confirms that vacancy and TM atom doping are effective means to enhance electrocatalytic performance and defect engineered Janus MoSiGeN4 can be served as highly efficient HER catalyst.

A post synthetically modified metal–organic framework as an efficient hydrogen evolution reaction catalyst in all pH conditions

Transition-metal-based metal–organic frameworks (MOFs) have received great interest for the development of low cost, platinum-free, non-precious water splitting electrocatalysts for hydrogen generation to resolve the energy crisis.

Ultrasonic spray pyrolysis synthesis of nano-cluster ruthenium on molybdenum dioxide for hydrogen evolution reaction

Platinum (Pt)-based catalyst is a state-of-the-art catalyst for hydrogen evolution reaction (HER) of electrochemical water splitting. Nevertheless, to minimize the overall water electrolysis cost, a new catalyst must be developed. Ruthenium (Ru)-based catalyst has recently been found to be an efficient HER catalyst in all pH ranges of electrolytes. However, they demonstrated lower HER activity than Pt-based catalysts. Hence, to maximize the electrocatalytic activity, a highly dispersed Ru-based catalyst should be studied while maintaining a high-loading amount. This study prepares a high-dispersed Ru catalyst using the ultrasonic spray pyrolysis (USP) process on a molybdenum dioxide (MoO2) support. The USP process enabled the dispersion of Ru on MoO2 with high-loading (10.3 wt%) and dispersion. The high dispersion of Ru and the strong interaction between Ru and MoO2 improved the HER activity.

A non-two-dimensional van der Waals InSe semispherical array grown by vapor–liquid–solid method for hydrogen evolution

Two-dimensional (2D) layered materials with layer-number dependent properties are promising candidates for next-generation noble-metal-free electrocatalytic reaction. However, the main group metal chalcogenides (MMCs) used for this purpose are rarely explored. Herein, we report the controlled growth of indium selenide (InSe) with a novel morphology (semispherical array) on a silicon substrate and its application in hydrogen evolution reaction (HER). The formation of the spherical InSe is explained with a vapor-liquid-solid growth mechanism, in which the distribution and size of the spheres could be facilely tuned by the reaction parameters. The InSe semispherical array was demonstrated as more efficient catalyst for HER than the flake-like 2D InSe counterparts, originating from the fully exposed InSe spherical surface with abundant adsorbing sites and the high crystalline quality for electron transport. This work provides a controlled synthesis way of the layered InSe with a distinct spherical morphology used for the electrocatalysis applications and could be extended to other main group metal chalcogenides.

Ultrafine Ru nanoparticles derived from few-layered Ti3C2Tx MXene templated MOF for highly efficient alkaline hydrogen evolution

It is meaningful to search high-efficient and inexpensive electrocatalysts for hydrogen evolution reaction (HER) due to the energy crisis and environmental pollution. Here, we report the preparation of ultrafine Ru nanoparticles from a hybrid of ZIF-L(Co) MOF and polydopamine coated few-layered Ti3C2Tx MXene (FL-Ti3C2Tx). FL-Ti3C2Tx is used as a template to grow regular leaf-shaped ZIF-L(Co) nanosheets through the reaction of Co ions anchored on the MXene surface with 2-methylimidazole. The obtained hybrid is then doped with Ru ions through ion exchange between Ru and Co ions, followed by thermal annealing at a temperature of 350 °C in an Ar atmosphere to produce ultrafine Ru nanoparticles. The obtained Ru@ZIF-L(Co)/FL-Ti3C2Tx nanocomposite shows outstanding HER performance with a low overpotential of 16.2 mV at a current density of 10 mA cm−2, a small Tafel slope of 21.0 mV dec−1 and excellent stability in 1.0 M KOH solution. This work provides a new strategy for the design and synthesis of highly efficient HER catalyst via MOFs with tunable composition and structure.

Electrochemical Surface Treatment to Enhance the Activity and Stability of Ni-P/CFP Electrocatalysts in Hydrogen Evolution Reaction

To construct an efficient and eco-friendly hydrogen economy, it is necessary to improve a cost competitiveness of green hydrogen. In this respect, a water electrolysis has been considered as an ideal production method of green hydrogen, where hydrogen evolution reaction (HER) is an irreplaceable cathodic reaction, while the various oxidative reactions such as oxygen evolution reaction (OER) or chlorine evolution reaction (CER) can be coupled as an anodic reaction. Because the HER becomes an essential reaction of water electrolysis, to facilitate efficient HER is one of the most important goal in a water electrolysis, in particular, to adopt and design the cost-effective HER catalysts are needed to lower the high activation energy of HER.As a theoretical and practical researches, a platinum (Pt) based compound is known as the most effective catalyst which has a zero-like proton adsorbed free energy in both of acidic and alkaline media, however its high cost owing to a high rarity of Pt becomes the research gap of HER catalyst. As a substitution of Pt based catalyst, transition metal phosphide (TMP) has received a lot of attention among the various non-noble metal based catalyst. Among them, nickel phosphide (Ni-P) is evaluated as the most suitable catalyst for HER due to the high catalytic activity and practical usefulness. The nickel (Ni) has lower electronegativity than phosphorus (P), and the electron transfers from the Ni to P. In other words, a proton and hydride adsorbed at the negatively charged P and positively charged Ni, respectively. Because homogeneous Ni metal has a lower kinetic of proton desorption than adsorption, the higher interaction between adsorbed proton and hydride increases the kinetic of not only desorption step but also overall HER. However, in conventional fabrication methods of Ni-P such as hydrothermal and electroplating, it is difficult to control the ratio of Ni and P, which might maximize the kinetics and moreover, stability.In this context, we suggest a surficial engineering process to control the ratio between Ni and P after the electroplating of Ni-P compound on carbon fiber paper (CFP) for the efficient HER catalyst in both of acidic and alkaline media. Because ‘isolated Ni’ which has a low bonding with P has different redox potential with Ni-P, the surficial engineering is designed as a dealloying cycle of metal alloy to selectively remove the isolated Ni. As a result, The Ni-P/CFPx10 and Ni-P/CFPx20 (10, 20 times dealloying-cycled Ni-P/CFP catalyst) catalysts show higher P content of 29.6 and 36.5 at% on the surface (24.9 at% before dealloying treatment). Furthermore, the surficial engineering arouses the recrystallization of Ni-P compound, thus the permeated amount of P increases according to the number of surficial engineering cycle. In particular, the Ni-P/CFPx20 and Ni-P/CFPx10 catalysts shows the 55 mV and 58 mV lower overpotential at -10 mA cm-2 the pristine Ni-P/CFP catalyst (179 mV for acidic HER and 247 mV for alkaline HER) in acidic and alkaline HER, respectively. Figure 1

Bimetallic Cobalt–Nickel Electrode Made by a Sputtering Technique for Electrocatalytic Hydrogen Evolution Reaction: Effect of Nickel Ratios

Electrocatalytic hydrogen evolution reaction (HER), a half-reaction of water splitting, is highly important to be developed for green and sustainable hydrogen production. In this work, a bimetallic cobalt–nickel (CoNix) alloy is deposited on nickel foam with a home-made target by using a radio frequency (RF) magnetron sputtering technique at a low deposition temperature. The as-sputtered CoNix was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy to evaluate its physical and chemical properties. The electrochemical measurement exhibited that the bimetallic CoNix alloy had a promising performance for HER in alkaline solutions. CoNi4, as the optimum ratio, possessed low overpotentials of 53 and 175 mV to achieve current densities of 10 and 100 mA/cm2, respectively. Moreover, among the as-sputtered CoNix, CoNi4 had the largest electrochemical surface-active area (485 cm2) and the lowest electron-transfer resistance (1.14 Ω). CoNi4 was also quite stable under the continuous operation of constant current densities of 10 and 50 mA/cm2 for 20 h. This work is based on the RF magnetron sputtering technique for developing bimetallic CoNix alloy as an efficient HER catalyst for electrochemical energy.

Dissociation of Pyridinethiolate Ligands during Hydrogen Evolution Reactions of Ni-Based Catalysts: Evidence from X-ray Absorption Spectroscopy.

The protonation of several Ni-centered pyridine-2-thiolate photocatalysts for hydrogen evolution is investigated using X-ray absorption spectroscopy (XAS). While protonation of the pyridinethiolate ligand was previously thought to result in partial dechelation from the metal at the pyridyl N site, we instead observe complete dissociation of the protonated ligand and replacement by solvent molecules. A combination of Ni K-edge and S K-edge XAS of the catalyst Ni(bpy)(pyS)2 (bpy = 2,2′-bipyridine; pyS = pyridine-2-thiolate) identifies the structure of the fully protonated catalyst as a solvated [Ni(bpy)(DMF)4]2+ (DMF = dimethylformamide) complex and the dissociated ligands as the N-protonated 2-thiopyridone (pyS-H). This surprising result is further supported by UV–vis absorption spectroscopy and DFT calculations and is demonstrated for additional catalyst structures and solvent environments using a combination of XAS and UV–vis spectroscopy. Following protonation, electrochemical measurements indicate that the solvated Ni bipyridine complex acts as the primary electron-accepting species during photocatalysis, resulting in separate protonated ligand and reduced Ni species. The role of ligand dissociation is considered in the larger context of the hydrogen evolution reaction (HER) mechanism. As neither the pyS-H ligand nor the Ni bipyridine complex acts as an efficient HER catalyst alone, the critical role of ligand coordination is highlighted. This suggests that shifting the equilibrium toward bound species by addition of excess protonated ligand (2-thiopyridone) may improve the performance of pyridinethiolate-containing catalysts.