High-performance Hydrogen Evolution Reaction Research Articles

In situ construction of layered transition metal phosphides/sulfides heterostructures for efficient hydrogen evolution in acidic and alkaline media

Construction of electrocatalysts with exceptional intrinsic activity and rich active sites has proved to be an effective strategy for remarkably enhancing the activity of the hydrogen evolution reaction (HER). In this work, durable and highly efficient layered Re2P/ReS2 (RePS) heterostructures were successfully fabricated by an in-situ phosphating layered ReS2. Taking advantage of the unique layered structure can provide abundant reaction active sites and the strong electronic interaction between ReS2 and Re2P can enhance the intrinsic activity, the optimized RePS electrocatalysts show superior catalytic activities of 69 and 57 mV at 10 mA cm−2 for HER in alkaline and acidic media, respectively. The density functional theory results suggest that the formed heterostructures between ReS2 and Re2P play an important role in optimizing the catalytic kinetics of the electrocatalysts. This work not only demonstrates that modulation of the electronic structure of catalysts is an efficient way to improve the HER activity but also confirms that the layered RePS heterostructure is a promising candidate for robust and high performance HER catalysts.

Interface engineering of MoS2–CoS2 heteronanosheets for enhanced electrochemical hydrogen evolution reaction

The heterostructured electrocatalysts with tunable electronic interaction and distinct synergetic effects have been confirmed as an efficient strategy for realizing high-performance hydrogen evolution reaction (HER). Herein, a simple synthetic strategy is reported for the growth of MoS2–CoS2 nanosheets on highly conductive reduced graphene oxide (MoS2–CoS2/RGO) to innovatively construct an electron-reconfiguration heterointerface. The strong electronic interactions between MoS2 and CoS2 interfaces lead to the redistribution of charge, which optimizes the adsorption-desorption of intermediates. Thus, the MoS2–CoS2/RGO exhibits superior catalytic activity toward HER with small overpotentials of 67 mV (1.0 M KOH) and 95 mV (0.5 M H2SO4), and remarkable stability. In addition, theoretical calculations reveal the redistribution of charge at the heterointerfaces, which decreases the energy barrier of adsorption for H intermediates and simultaneously enhances the kinetic of water dissociation. This work provides a simple strategy for designing heterostructured bimetallic electrocatalysts with a highly active interface.

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.

Ultrasmall and Highly Dispersed Pt Entities Deposited on Mesoporous N-doped Carbon Nanospheres by Pulsed CVD for Improved HER.

Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300°C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (≈1nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250°C) reveals a Pt HER mass activity of 22.2 ± 1.2Amg-1 Pt at -50mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2Amg-1 Pt at -50mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far.

Boosting electrocatalytic activity of Ru for hydrogen evolution through engineering Ru on multiple interfaces of 1T-MoS2 and carbon

Ru is considered as highly efficient Pt-free catalyst in hydrogen evolution reaction (HER) due to its fast water dissociation kinetics. However, its strong affinity to OH* and H* greatly limits its HER performance. Herein, Ru nanoparticles (NPs) anchored on the mixed substrates of MoS2 (different 1T contents) and carbon fiber paper (Ru@MoS2-1T%/CFP) is designed and synthesized with three kinds of interfaces (MoS2/CFP, Ru/CFP, and Ru/MoS2) as excellent electrocatalyst for HER. Particularly, the Ru2@MoS2-85%/CFP presents superb HER performance with overpotential of 19 mV at 10 mA cm−2, a low Tafel slope of 29 mV dec–1 and stability of up to 10 days, outperforming reported Ru-based catalysts and Pt/C. The experimental and DFT studies disclose that the hydroxyl migration-assisted dissociation of water and interface-engineering desorption of H2 process, occurring at the mutually hybridized interface sites of Ru/MoS2/CFP, simultaneously speed Volmer/Tafel processes. Compared to Ru, the stronger interaction of 1T-MoS2 to OH* makes OH* migrate from Ru to MoS2, alleviating the poisoning of Ru sites. Also, only Ru NPs close to the interface of 1T-MoS2/CFP can achieve an optimal hydrogen adsorption energy for high HER performance. This designed strategy provides a novel idea for preparing supported Ru catalysts for excellent HER performance.

Electrochemical deposition of nickel sulfide catalysts on commercial carbon rods as low-cost electrodes for hydrogen generation

Nowadays, the challenge of the world and the scientific community is to find and effectively use renewable energy sources. One of the renewable energy research subjects that has been hotly discussed recently is the water-splitting reaction to produce hydrogen. In this study, we focus on fabricating nickel sulfide (NiS) materials deposited on commercial carbon rod (CR) substrates and using them as electrodes for the electrochemical water-splitting reaction to produce hydrogen gas. In detail, NiS materials were decorated on commercial carbon rods (NiS/CR) by cyclic voltammetry electrochemical deposition with a potential range from 0.2 to −1.2 V (versus Ag/AgCl), a scan rate of 10 mV s−1, and 15 cycles. Benefiting a strong interfacial synergetic effect based on NiS/CR materials shows an excellent electrocatalytic activity for hydrogen evolution reaction (HER). Specifically, the NiS/CR electrode exhibits a high performance with low overpotential (70 mV for HER) and a slight Tafel slope (50 mV dec−1). Besides, annealing temperature helps increase the crystal properties, causing the appearance of NiS2 and Ni3S2 phases in NiS/CR@400 samples. Interestingly, the electrochemical surface area (ESCA) of the NiS/CR@400 sample significantly increased (17.3%) compared to the NiS/CR sample (5.8% of the total physical surface area) is due to the presence of NiS2 and Ni3S2, leading to NiS/CR@400 sample enhances the active sites by 16.0 mF cm−2. Furthermore, the long-term durability of NiS/CR@400 electrodes is good electrocatalytic over a continuous cycling 12-hour operation at 20 mA cm−2 in an alkaline environment. The NiS/CR is a promising electrode candidate for high HER performance, and here is a new design of electrocatalysts for water splitting.

Unravelling the role of work function difference on supported Ru nanoclusters for alkaline hydrogen evolution reaction

Fine tuning the work function difference (ΔΦ) between support and Ru which in turn affects the electron distribution of Ru is an effective method for the design of high-performance alkaline hydrogen evolution reaction (HER) catalysts. However, it remains a challenge to understand the intrinsic relationship between HER activity and ΔΦ at the atomic level. Herein, taking N doped graphene supported Ru nanoclusters (Ru/CxNy) as the theoretical model, we demonstrate that the HER activity can be correlated with the variation of ΔΦ. For Ru/C50 with smaller ΔΦ, we find that the Ru atoms located at the top layer of Ru nanoclusters (Ru-t) with lower coordination numbers are the main reaction sites. For Ru/C30N20 with larger ΔΦ, the stronger charge redistributions of Ru is observed, and the electron-deficient Ru atoms closing to the interface (Ru-i) are the main reaction sites with significant improvement HER activity. Our findings demonstrate the role of ΔΦ on Ru/CxNy systems for the alkaline HER, which can provide valuable theoretical guidance for the design of high efficient HER catalysts.

Screening of transition metal dual-atom catalysts for hydrogen evolution reaction based on high-throughput calculation and searching surrogate prediction model using simple features

Dual-atom catalysts for hydrogen evolution reaction have received widespread attention, but precise screening and prediction of high-performance catalysts through simple methods remains a challenge. In this study, we perform high-throughput density functional theory (DFT) calculation and machine learning (ML) to screen and predict the transition metal dual-atom catalysts with N-doped graphene support (TMDACs) for acidic hydrogen evolution reaction (HER). The Fe_Zn and V_Fe DACs were proposed to be the most promising candidates for Pt-based catalyst toward acidic HER from 406 TMDACs, based on the characteristics of HER activity, formation, thermodynamic stability, abundance, environmental friendliness. The Fe_Zn and V_Fe DACs with excellent HER performance is due to the synergistic effect deriving from the interaction between H and dual metal atoms in TMDACs. By determining 6 different ML models with four kind of input features, we find the artificial neural networks (ANN) model can predict the HER performance of TMDACs most accurately only using simple input features, including one-hot-encoding of atomic number and Gibbs free energies of transition metal single-atom catalysts. This work not only proposed the potential TMDACs with high HER performance, but also verified that the ANN model can accurately predict the HER activity of diatomic catalysts with simple input features.

Comparative study on various morphologies of WS2 for electrochemical hydrogen evolution reaction

Nowadays, the advancement of cost-effective and efficient electrocatalysts holds significant importance in facilitating the progress of high-performance electrochemical hydrogen evolution reaction (HER). Tungsten disulfides (WS2) are well recognized as highly promising electrocatalysts for HER due to their exceptional catalytic performance, outstanding stability, and comparatively affordable price. In this study, we used ammonium metatungstate hydrate and thioacetamide as precursors to fabricate WS2 nanoflowers (NFs) by hydrothermal method, whereas WS2-flakes were prepared from ammonium tetrathiotungstate through the thermolysis technique. These structures were evaluated for HER electrocatalytic activity in acidic media. The results revealed that WS2-NFs exhibit higher catalytic activity than WS2-flakes, with an overpotential of 325 mV to obtain a current density of 10 mA cm−2 and a Tafel slope of 92.3 mV dec−1. This performance was attributed to the larger electrochemically active surface area of WS2-NFs compared to WS2-flakes materials. The results of this study could bring the basis for further studies on the synthesis of WS2-based catalytic materials for HER. ® 2023 Journal of Science and Technology - NTTU

Compressed Ru skin on atomic-ordered hexagonal Ru-Ni enabling rapid Volmer-Tafel kinetics for efficient alkaline hydrogen evolution

Ru-based materials are promising electrocatalysts for hydrogen evolution reaction (HER) owing to their low-cost (one twenty-fifth of Pt) and similar Gibbs free energy of H* adsorption (ΔGH*) to that of Pt. However, the inadequate ability for the water dissociation of Ru catalysts is significantly impeding the water splitting efficiency. In this work, we demonstrate an atomically ordered hexagonal Ru-Ni alloy with compressive-strained Ru skin as a high-performance HER catalyst for significantly boosting the water dissociation. The Ordered Ru-Ni achieves an optimized catalytic activity for alkaline HER with a low overpotential of 23 mV at 10 mA cm−2, Tafel slope of 25.9 mV dec−1 and superior mass activity of 4.83 A mg−1Ru, which is 15.1 times higher than Ru/C. According to DFT calculations, the ordered RuNi core imposes homogeneous compressive strain on the Ru skin, resulting in an optimum binding energy towards H*/OH* intermediates on Ru active sites for rapid Tafel step kinetics. Moreover, the decreased H2O dissociation energy barrier of Ordered Ru-Ni suggests a promoted Volmer-Tafel kinetics is achieved, significantly boosting the overall HER efficiency. This work provides a practical avenue for surface strain engineering of Ru-based catalysts to promote the HER activity.

P-Ni co-doped Mo2C embedded in carbon-fiber paper as a highly efficient electrocatalyst for hydrogen evolution in alkaline media

The development of noble-metal-free electrocatalysts with high electrocatalytic performance and stability by adopting a scalable route is key to solving the energy crisis. We report a PNi co-doped Mo2C-based electrocatalyst with high hydrogen evolution reaction (HER) catalytic activity prepared by a molten-salt method. Using phosphating times of 2 h and 4 h yielded P-Ni-Mo2C-2h and P-Ni-Mo2C-4h, respectively, both of which exhibited nanoflower-like structures that provided abundant active sites for the reaction. P-Ni-Mo2C-2h possessed good electrocatalytic properties with a low overpotential of only 140.5 mV at j = 10 mA cm−2 and a small Tafel slope of 50.7 mV dec−1 in an alkaline environment. P-Ni-Mo2C-2h exhibited excellent stability after 20 h of continuous hydrogen production. The use of an excessively long phosphating time caused a narrow down of spaces formed by nanoflakes, thereby reducing the HER performance of the electrocatalyst. The results of this study provide guidelines for the preparation of high-efficiency PNi co-doped electrocatalysts.

Spin Polarization of 2D Weyl Semimetal Fe2Sn Enabling High Hydrogen Evolution Reaction Activity.

It is well known that magnetic field is one of the effective tools to improve the activity of hydrogen evolution reaction (HER), but considering the inconvenient application of an external magnetic field, it is essential to find a ferromagnetic material with high HER activity itself. Fortunately, recent study has shown that the two-dimmention (2D) Fe2Sn monolayer is a stable ferromagnetic topological Weyl semimetal material with high Tc of 433 K. Here, we report the Fe2Sn monolayer can be used as an alternative HER catalyst compared with expensive platinum (Pt). Our first-principles results show that the Gibbs free energy (ΔGH*) value of the spin polarized Fe2Sn monolayer is -0.06 eV, much better than that without considering spin polarization (-1.23 eV). Moreover, the kinetic analysis demonstrates that the HER occurs on the Fe2Sn monolayer according to the Volmer-Tafel mechanism with low energy barriers. Hence, our findings provide obvious evidence for spin-polarization-improved HER activity, paving a new way to design high-performance HER catalysts.

In Situ Active Site Refreshing of Electro‐Catalytic Materials for Ultra‐Durable Hydrogen Evolution at Elevated Current Density

AbstractEnhancing the durability of catalysts is of critical significance to industrialize green hydrogen production. Herein, a novel active site in situ refreshing strategy is proposed and demonstrated to fabricate highly active and ultra‐durable hydrogen evolution reaction (HER) electro‐catalytic material by HER activation. Briefly, a composite catalytic material is synthesized, which features Ni(PO3)2 active sites being embedded inside the amorphous Mo compound matrix (named NiMoO‐P). The Mo compound matrix undergoes gradual dissolution during HER followed by a dynamic equilibrium between the dissolution and deposition of the amorphous matrix. This process promotes the continuous exposure of insoluble Ni(PO3)2 and Ni2P partially converted from Ni (PO3) 2 in situ on the surface during HER activation. Thus, activated catalyst exhibits excellent HER performance featuring an extremely high current density of 1500 mA cm−2 at a rather low overpotential of 340 mV, and more attractively, an ultra‐long durability for hydrogen evolution for at least 1000 h at an industrial‐applicable current density of 900 mA cm−2. The mechanisms for the especially high HER performance are attributed to the exposure and continuous refreshing of Ni(PO3)2 and the in situ formed Ni2P during the HER process based on the DFT calculations and quasi‐in situ Raman spectroscopic monitoring.

Universal electronic descriptors for optimizing hydrogen evolution in transition metal-doped MXenes

The integration of transition metal (TM) atoms into two-dimensional (2D) transition metal carbides and nitrides (MXenes) has been identified as a promising strategy for enhancing hydrogen evolution reaction (HER) performance. However, the vast combinatorial space presents challenges for rapid catalyst screening. In response, high-throughput calculations were conducted on Ti2CO2 and Zr2CO2 doped with a wide array of TM single atoms. The local structural and corresponding electronic structural changes were analyzed, with an emphasis on their implications for HER performance. Furthermore, universal electronic descriptors were developed using the Sure Independence Screening and Sparsifying Operator (SISSO) method, harmonizing the Gibbs free energy of hydrogen adsorption (ΔGH*) trends across different MXenes substrates doped with TM atoms. These descriptors enabled the prediction of Cr, Fe, Ru, Pd, Os, and Ir as effective dopants for optimizing the ΔGH* of Hf2CO2, resulting in a reduction of ΔGH* from 1.082 eV to within ±0.2 eV. Our work not only highlights the potential of these TM dopants in significantly enhancing the catalytic activity of MXenes but also underscores the value of universal electronic structure descriptors in rapidly identifying and developing high-performance HER catalysts.

Defect engineering of 1T′ MX 2 (M = Mo, W and X = S, Se) transition metal dichalcogenide-based electrocatalyst for alkaline hydrogen evolution reaction

The alkaline electrolyzer (AEL) is a promising device for green hydrogen production. However, their energy conversion efficiency is currently limited by the low performance of the electrocatalysts for the hydrogen evolution reaction (HER). As such, the electrocatalyst design for the high-performance HER becomes essential for the advancement of AELs. In this work, we used both hydrogen (H) and hydroxyl (OH) adsorption Gibbs free energy changes as the descriptors to investigate the catalytic HER performance of 1T′ transition metal dichalcogenides (TMDs) in an alkaline solution. Our results reveal that the pristine sulfides showed better alkaline HER performance than their selenide counterparts. However, the activities of all pristine 1T′ TMDs are too low to dissociate water. To improve the performance of these materials, defect engineering techniques were used to design TMD-based electrocatalysts for effective HER activity. Our density functional theory results demonstrate that introducing single S/Se vacancy defects can improve the reactivities of TMD materials. Yet, the desorption of OH becomes the rate-determining step. Doping defective MoS2 with late 3d transition metal (TM) atoms, especially Cu, Ni, and Co, can regulate the reactivity of active sites for optimal OH desorption. As a result, the TM-doped defective 1T′ MoS2 can significantly enhance the alkaline HER performance. These findings highlight the potential of defect engineering technologies for the design of TMD-based alkaline HER electrocatalysts.

Comparative study on various morphologies of WS2 for electrochemical hydrogen evolution reaction

Nowadays, the advancement of cost-effective and efficient electrocatalysts holds significant importance in facilitating the progress of high-performance electrochemical hydrogen evolution reaction (HER). Tungsten disulfides (WS2) are well recognized as highly promising electrocatalysts for HER due to their exceptional catalytic performance, outstanding stability, and comparatively affordable price. In this study, we used ammonium metatungstate hydrate and thioacetamide as precursors to fabricate WS2 nanoflowers (NFs) by hydrothermal method, whereas WS2-flakes were prepared from ammonium tetrathiotungstate through the thermolysis technique. These structures were evaluated for HER electrocatalytic activity in acidic media. The results revealed that WS2-NFs exhibit higher catalytic activity than WS2-flakes, with an overpotential of 325 mV to obtain a current density of 10 mA cm−2 and a Tafel slope of 92.3 mV dec−1. This performance was attributed to the larger electrochemically active surface area of WS2-NFs compared to WS2-flakes materials. The results of this study could bring the basis for further studies on the synthesis of WS2-based catalytic materials for HER.
 ® 2023 Journal of Science and Technology - NTTU

Ultrathin core–shell–satellite structured Au@PtPd@Pt nanowires for superior electrocatalytic hydrogen evolution

The rational structural and compositional design of Pt-based electrocatalysts is effective in synergizing the physicochemical and electrochemical properties of Pt for developing high-performance hydrogen evolution reaction (HER) electrocatalysts.

Honeycomb-like hollow carbon loaded with ruthenium nanoparticles as high-performance HER electrocatalysts

A honeycomb-like N-doped hollow carbon material loaded with a low content of ruthenium nanoparticles was prepared as an efficient HER catalyst, and its performance is even superior to that of commercial Pt/C.

In Situ Construction of Built-In Opposite Electric Field Balanced Surface Adsorption for Hydrogen Evolution Reaction.

Achieving a balance between H-atom adsorption and binding with H2 desorption is crucial for catalyzing hydrogen evolution reaction (HER). In this study, the feasibility of designing and implementing built-in opposite electric fields (OEF) is demonstrated to enable optimal H atom adsorption and H2 desorption using the Ni3(BO3)2/Ni5P4 heterostructure as an example. Through density functional theory calculations of planar averaged potentials, it shows that opposite combinations of inward and outward electric fields can be achieved at the interface of Ni3(BO3)2/Ni5P4, leading to the optimization of the H adsorption free energy (ΔGH*) near electric neutrality (0.05eV). Based on this OEF concept, the study experimentally validated the Ni3(BO3)2/Ni5P4 system electrochemically forming Ni3(BO3)2 through cyclic voltammetry scanning of B-doped Ni5P4. The surface of Ni3(BO3)2 undergoes reconstruction, as characterized by Grazing Incidence Wide-Angle X-ray Scattering (GIWAXS) and in situ Raman spectroscopy. The resulting catalyst exhibits excellent HER activity in alkaline media, with a low overpotential of 33mV at 10mA cm-2 and stability maintained for over 360 h. Therefore, the design strategy of build-in opposite electric field enables the development of high-performance HER catalysts and presents a promising approach for electrocatalyst advancement.

Synthesis of FeNi-based heterostructure on a nickel foam at room temperature for efficient catalyzing hydrogen evolution reaction

The FeNi-based heterostructure was synthesized on a nickel foam by a simple dip-coating method with zero-energy consumption at room temperature. The obtained heterostructure is flower-like and has high-performance for electrocatalyzing the hydrogen evolution reaction (HER). On the FeNi-based heterostructure, the overpotential was only 228 mV at a current density of 100 mA cm−2 in 1 M KOH, and can maintain 10 h stability with chronoamperometry test. The outstanding catalytic activity was attributed to the unique structure with a large electrochemical active surface area and the synergistic effect between different transition metal elements. This research afforded a new way to design low-cost and high-performance HER electrocatalyst.