Alkaline Hydrogen Evolution Reaction Research Articles

Mo Migration‐Induced Crystalline to Amorphous Conversion and Formation of RuMo/NiMoO4 Heterogeneous Nanoarray for Hydrazine‐Assisted Water Splitting at Large Current Density

AbstractManipulating the atomic structure of the catalyst and tailoring the dissociative water‐hydrogen bonding network at the catalyst‐electrolyte interface is essential for propelling alkaline hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR), but remains a great challenge. Herein, we constructed an advanced a‐RuMo/NiMoO4/NF heterogeneous electrocatalyst with amorphous RuMo alloy nanoclusters anchored to amorphous NiMoO4 skeletons on Ni foam by a heteroatom implantation strategy. Theoretical calculations and in situ Raman tests show that the amorphous and alloying structure of a‐RuMo/NiMoO4/NF not only induces the directional evolution of interfacial H2O, but also lowers the d‐band center (from −0.43 to −2.22 eV) of a‐RuMo/NiMoO4/NF, the Gibbs free energy of hydrogen adsorption (ΔGH*, from −1.29 to −0.06 eV), and the energy barrier of HzOR (ΔGN2(g)=1.50 eV to ΔGN2*=0.47 eV). Profiting from these favorable factors, the a‐RuMo/NiMoO4/NF exhibits excellent electrocatalytic performances, especially at large current densities, with an overpotential of 13 and 129 mV to reach 10 and 1000 mA cm−2 for HER. While for HzOR, it needs only −91 and 276 mV to deliver 10 and 500 mA cm−2, respectively. Further, the constructed a‐RuMo/NiMoO4/NF||a‐RuMo/NiMoO4/NF electrolyzer demands only 7 and 420 mV to afford 10 and 500 mA cm−2.

Synergistic Alkaline Hydrogen Evolution Catalysis over MoC Triggered by Doping Single Ru Atoms

AbstractThe rational design of single atom‐based catalysts and precise elucidation of the synergistic interaction between the metal site and substrate are pivotal to identifying the real active sites and explicating the catalytic mechanisms at the atomic scale, thus contributing to the development of high‐performance catalysts for diverse industrial implementations. Herein, a Ru single‐atom doping strategy is developed to activate the MoC substrate with superior hydrogen evolution reaction (HER) activity in an alkaline medium. The atomically dispersed Ru sites are elaborately doped into MoC nanoparticles loaded on 3D N‐doped carbon nanoflowers (Ru‐SAs@MoC/NCFs hereafter). The experimental results and theoretical calculations manifest that the atomically isolated Ru dopants can effectively trigger the Mo sites with thermodynamically favorable water adsorption/dissociation energies and facilitate the OH− desorption on Ru sites and H adsorption on N sites, thus synergistically expediating the overall alkaline HER kinetics. As such, the well‐designed Ru‐SAs@MoC/NCFs demonstrate extraordinary HER activity with a low overpotential of 16 mV at 10 mA cm−2 in 1.0 m KOH electrolyte, outperforming Pt/C benchmark and a vast of molybdenum/ruthenium‐based HER catalysts reported to date. These findings disclose the alkaline HER mechanistic induced by the atomic doping modulation and suggest a design principle of high‐efficiency electrocatalysts via the atomic‐level manipulation leverage.

Efficient Solvothermal Synthesis of Defect-Rich Cu-BTC•MOF with Enhanced Electrocatalytic Activity in Alkaline Hydrogen Evolution Reaction

Efficient Solvothermal Synthesis of Defect-Rich Cu-BTC•MOF with Enhanced Electrocatalytic Activity in Alkaline Hydrogen Evolution Reaction

Multi-synergy enabling Ni-doped MoS2@N-doped carbon composite as versatile catalysts toward hydrogen production and photovoltaics

Construction of efficient non-precious catalyst with desired chemical composition and well-defined nanostructure is of great essential to enhance the kinetics of hydrogen evolution reaction (HER) and triiodide (I3−) reduction reaction (IRR), which is conducive to promote the development of green hydrogen production and obtain impressive photovoltaic performance of dye-sensitized solar cells (DSSCs). Herein, ZIF-8 derived N-doped carbon (NC) wrapped with two-dimensional Ni-doped MoS2 nanosheets (Ni–MoS2@NC) are elaborately designed. The catalytic activity of Ni–MoS2@NC for HER and IRR are significantly improved by modifying electronic structure through heteroatom doping. The optimized Ni–MoS2@NC has lower overpotential of 122 mV at 10 mA cm−2 in comparison with counterpart. Meanwhile, the power conversion efficiency (PCE) of DSSCs based on Ni–MoS2@NC CE catalyst is comparable to that of Pt. Density functional theory (DFT) calculation is used to unveil the mechanism of Ni–MoS2@NC for alkaline HER and IRR, namely, the multi-synergy of various sites endows Ni–MoS2@NC with appropriate Gibbs free energy for H∗ adsorption and water dissociation energy, while the top and interfacial S sites of Ni–MoS2@NC are responsible for the adsorption and activation of I3−. Our work provides a feasible route to design efficient catalysts in the field of energy conversion and understand mechanism.

Sustainable hydrogen production with synergistic electron transfer enhancement in nickel-based alkaline HER electrocatalyst empowered by graphene oxide

The hydrogen evolution reaction (HER) plays a crucial role in driving forward the transition to a hydrogen-based economy by providing a means to generate pure hydrogen. However, the efficient and cost-effective production of hydrogen via HER faces significant challenges, particularly at the cathode. To address these challenges, we produced a hybrid material – 2D graphene oxide (GO) sheets coated onto nickel sulfide (NiS) microspheres anchored on Ni Foam (GO@NiS/Ni Foam) using a straightforward synthesis technique. Our research highlights the significant influence of the interaction between GO and NiS on the performance of HER, attributed to the enhancement of electron transport at the interface. Furthermore, the GO@NiS/Ni Foam composite exhibits remarkable durability over extended periods, maintaining its superior functionality for up to 40 h of continuous operation. This underscores its potential for practical implementation in efficient water-splitting processes, offering a promising solution to the challenges hindering widespread adoption of hydrogen technology.

Application of Hydrogen Spillover to Enhance Alkaline Hydrogen Evolution Reaction

AbstractAlkaline water splitting has shown great potential for industrial‐scale hydrogen production. However, its broad application is constrained by hydrogen evolution reaction (HER) electrocatalysts, which struggle to achieve optimal current density at low overpotential. The utilization of the hydrogen spillover effect to augment the performance of HER represents a burgeoning area of research. Although previous studies mainly focused on hydrogen spillover in acidic media, the latest studies have shown that hydrogen spillover also exists under alkaline conditions, and its role in improving HER performance cannot be ignored. This review examines the mechanisms of HER under acidic and alkaline conditions, elucidating the distinctive behavior of hydrogen spillover in these environments and its influence on catalytic processes. At the same time hydrogen spillover characterization methods are systematically summarized, these technologies for understanding and control of hydrogen release process provides strong support. Finally, the recent electrocatalysts that enhance the catalytic performance of alkaline HER by hydrogen spillover effect are comprehensively sorted out and summarized. This review not only demonstrate the practical value of hydrogen spillover under alkaline conditions, but also provide new directions for future design and optimization of electrocatalysts.

Coupled Lattice‐Expanded Ni and MoO2 Array for Efficient Alkaline Hydrogen Evolution

AbstractTransition metal oxides have attracted much attention due to their good electrical conductivity, high chemical stability, and easy electronic structure modulation. However, it is still a great challenge to solve the problems of sluggish reaction kinetics and high overpotential in the alkaline hydrogen evolution reaction (HER) due to their poor intrinsic activity. Herein, a lattice‐expanded Ni‐decorated MoO2 array (Ni‐MoO2‐700) catalyst is prepared for the alkaline HER. Unlike most of the reported literature, the decoration of metal heteroatoms may lead to lattice expansion of the carrier catalyst. In contrast, lattice expansion of Ni is also achieved by adjusting the annealing temperature in this work. The Ni‐induced lattice‐expanding effect can not only modulate the electronic structure of the catalyst but also accelerate electron transfer during the reaction, thus increasing its intrinsic activity for the HER. As a result, Ni‐MoO2‐700 exhibits significantly enhanced catalytic activity with an overpotential of 74.9 mV at 10 mA cm−2 in 1.0 m KOH, which is far superior to that of most of the reported advanced Ni‐ and Mo‐based materials. This work provides deep intrinsic insight and a great opportunity to design efficient transition metal oxide catalysts for the alkaline HER.

Boosting HER performance by using plasma prepared N-doped CNTs to support Pt nanoparticles

Developing highly-efficient and stable Pt-based catalysts towards alkaline hydrogen evolution reaction (HER) offers a promising strategy for future renewable energy. In this work, radio-frequency (RF) cold plasma-prepared N-doped MWCNTs were adopted to support Pt nanoparticles (NPs) (Pt/NCNTs) via pretreating MWCNTs with RF nitrogen plasma and combining with traditional thermal reduction method. The as-synthesized Pt/NCNT featured an ultra-small size of Pt NPs (1.5 nm) and plentiful doped nitrogen, exhibiting ultra-low overpotential of 28 mV@10 mA cm−2 and ultra-high mass activity of 3.2 A mg Pt−1@100 mA in 1 M KOH solution, which are superior to those of commercial 20 wt% Pt/C catalyst. This is because RF plasma can realize fast, high-efficient and specific N-doping structure of MWCNTs. The lone electron pairs of N species (mainly pyri-N and pyrr-N) on MWCNTs surface transfer to the empty orbitals of Pt NPs, forming a strong coordination effect between Pt and nitrogen, thereby boosting the alkaline HER catalytic performance.

Self-Supporting FeCoNiCuTiGa High-Entropy Alloy Electrodes for Alkaline Hydrogen and Oxygen Evolution Reactions: Experimental and Theoretical Insights

Self-Supporting FeCoNiCuTiGa High-Entropy Alloy Electrodes for Alkaline Hydrogen and Oxygen Evolution Reactions: Experimental and Theoretical Insights

Rationally Designed Mo/Ru-Based Multi-Site Heterogeneous Electrocatalyst for Accelerated Alkaline Hydrogen Evolution Reaction.

The rational design of multi-site electrocatalysts with three different functions for facile H2O dissociation, H-H coupling, and rapid H2 release is desirable but difficult to achieve. This strategy can accelerate the sluggish kinetics of the hydrogen evolution reaction (HER) under alkaline conditions. To resolve this issue, a Mo/Ru-based catalyst with three different active sites (Ru/Mo2C/MoO2) is rationally designed and its performance in alkaline HER is evaluated. The experimental results and density functional theory calculations revealed that, at the heterogeneous Mo2C/MoO2 interface, the higher valence state of Mo (MoO2) and the lower valence state of Mo (Mo2C) exhibited strong OH- and H-binding energies, respectively, which accelerated H2O dissociation. Moreover, the interfacial Ru possessed an appropriate hydrogen binding energy for H-H coupling and subsequent H2 evolution. Thus, this catalyst significantly accelerated the Volmer step and the Tafel step and, consequently, HER kinetics. This catalyst also demonstrated low overpotentials of 19 and 160mV at current densities of 10 and 1000mA cm-2, respectively, in alkaline media and long-term stability superior to that of most state-of-the-art alkaline HER electrocatalysts. This work provides a rational design principle for advanced multi-site catalytic systems, which can realize multi-electron electrocatalytic reactions.

Self-Standing Mo/MoO2 Porous Flake Arrays for Efficient Hydrogen Evolution Reaction in High-pH Media.

The alkaline hydrogen evolution reaction (HER) is limited by scarce proton availability, resulting in slower reaction kinetics compared to those under acidic conditions. Enhancing the local chemical environment of protons on the catalyst surface can improve the intrinsic reaction kinetics. Here, we design a Mo/MoO2 metallic heterojunction that creates an acidic-like environment with a proton-rich surface, significantly enhancing HER performance in alkaline electrolytes, as confirmed by in situ spectroscopy and electrochemical analysis. A self-standing Mo/MoO2 catalytic electrode is fabricated via a controlled pyrolysis-reduction strategy. This electrode exhibits exceptional HER activity, with low overpotentials of 65 mV at 10 mA cm-2 and 315 mV at 500 mA cm-2, a Tafel slope of 38.2 mV dec-1, and stability exceeding 60 h at -300 mA cm-2 in alkaline solution. The porous flake array structure of the Mo/MoO2 heterojunctions enhances the adjacent hydronium (H3O+) concentration, resulting in a ΔGH* value of 0.15 eV and a water dissociation energy barrier of 0.37 eV in an alkaline medium. The successful preparation of a large-area electrode (2 cm × 2 cm) demonstrates the scalability of this approach for fabricating molybdenum-based catalytic electrodes with enhanced HER activity in alkaline environments.

Multi-interface and rich-defects 1T phase MoS2 combine with FeS anchored on reduced graphene oxide for efficient alkaline hydrogen evolution

Exploring and fabricating noble-metal-free and cost-effective electrocatalysts to minimise the excessive potential required is of great significance for alkaline hydrogen evolution reaction (HER). Herein, we report FeS/1T-MP MoS2@rGO heterostructure with 1T and 2H mixed phase MoS2 (1T-MP MoS2) combining with FeS anchored on reduced graphene oxide (rGO) matrix, which is synthetized by utilizing Anderson polyoxometalate as Fe–Mo precursor by a facile hydrothermal method. The FeS/1T-MP MoS2@rGO heterostructure in the form of interconnected nanosheet arrays with multiple interfaces and rich-defects, which is in favor of the immersion of the electrolyte and exposing more active sites. Benefiting from the synergistic advantages of 1T-MoS2, FeS and rGO, FeS/1T-MP MoS2@rGO heterostructure delivers enhanced conductivity, enlarged electrochemical active surface area, and eventually promote the HER kinetics. As expected, FeS/1T-MP MoS2@rGO heterostructure emerges prominent HER activity with low overpotentials of 102 and 256 mV to achieve current density of 10 and 100 mA cm−2, outperforming vast majority of the advanced 1T MoS2-based alkaline HER electrocatalysts.

Evaluating the Hydrogen Evolution Reaction Activity of Colloidally Prepared PtSe2 and PtTe2 Catalysts in an Alkaline Medium.

The hydrogen evolution reaction (HER) in alkaline electrolytes using transition metal dichalcogenides is a research area that is not tapped into. Alkaline HER ( ) is harder to achieve relative to acidic HER ( ), this is attributed to the additional water dissociation step that occurs in basic HER to generate H+ ions. In fact, for most catalysts, their HER activity decreases tremendously when the electrolyte is changed from acidic to basic conditions. Platinum dichalcogenides, PtX2 (X=S, Se, Te), are an interesting member of transition metal dichalcogenides (TMDs) as these show an immense hybridization of the Pt d orbitals and chalcogen p orbitals because of closely correlated orbital energies. The trend in electronic properties of these materials changes drastically as the chalcogen is changed, with PtS2 reported to exhibit semi-conductor properties, PtSe2 is semi-metallic or semi-conductive, depending on the number of layers, while PtTe2 is metallic. The effect of varying the chalcogen atom on the HER activity of Pt dichalcogenides will be studied. Pt dichalcogenides have previously been prepared by direct high-temperature chalcogen deposition of Pt substrate and evaluated as electrocatalysts for HER in H2SO4. The previously employed synthesis procedures for PtX2 limit these compounds' mass production and post-synthesis treatment. In this study, we demonstrated, for the first time the preparation of PtSe2 and PtTe2 by colloidal synthesis. Colloidal synthesis offers the possibility of large-scale synthesis of materials and affords the employment of the colloids at various concentrations in ink formulation. The electrochemical HER results acquired in 1 M KOH indicate that PtTe2 has a superior HER catalytic activity to PtSe2. A potential of 108 mV for PtTe2 and 161 mV for PtSe2 is required to produce a current density of -10 mA cm-2 from these catalysts. PtTe2 has a low Tafel slope of 79 mVdec-1, indicating faster HER kinetics on PtTe2. Nonetheless, the stability of these catalysts in an alkaline medium needs to be improved to render them excellent HER electrocatalysts.

Bimetal Metaphosphate/Molybdenum Oxide Heterostructure Nanowires for Boosting Overall Freshwater/Seawater Splitting at High Current Densities.

Exploring excellent non-noble bifunctional electrocatalysts for freshwater/seawater splitting at high current densities has attracted extensive interest owing to strong anodic oxidation and severe chloride corrosion challenges. Herein, hierarchical bimetal Ni-Co metaphosphate/molybdenum oxide heterostructure nanowires (NiCoMoPO) are rationally designed and fabricated to efficiently boost oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline freshwater/seawater, where the favorable electronic structure from heterostructures, signified by X-ray absorption spectra, endows NiCoMoPO with the enhanced intrinsic activity, while its hierarchical nanowire structure and heterostructures provide abundant active sites. Additionally, the PO3 - improves the chloride-corrosion resistance and efficiently facilitates the OER kinetics verified by theoretical and experimental studies. Therefore, NiCoMoPO drives 1000mA cm-2 at low overpotentials of 467 and 442mV for OER and HER in alkaline freshwater respectively, as well as a small cell voltage of 2.135V for overall freshwater splitting with robust durability of 300h. Impressively, due to the strong corrosion resistance, at 500mA cm-2 of overall seawater splitting, NiCoMoPO maintains almost 2.096V for 1200h, indicating promising practical applications. This work sheds light on the rational design and fabrication of outstanding electrocatalysts at high current densities of seawater/freshwater splitting.

Unlocking Efficient Alkaline Hydrogen Evolution Through Ru-Sn Dual Metal Sites and a Novel Hydroxyl Spillover Effect.

Alkaline hydrogen evolution reaction (HER) has great potential in practical hydrogen production but is still limited by the lack of active and stable electrocatalysts. Herein, the efficient water dissociation process, fast transfer of adsorbed hydroxyl and optimized hydrogen adsorption are first achieved on a cooperative electrocatalyst, named as Ru-Sn/SnO2 NS, in which the Ru-Sn dual metal sites and SnO2 heterojunction are constructed based on porous Ru nanosheet. The density functional theory (DFT) calculations and in situ infrared spectra suggest that Ru-Sn dual sites can optimize the water dissociation process and hydrogen adsorption, while the existence of SnO2 can induce the unique hydroxyl spillover effect, accelerating the hydroxyl transfer process and avoiding the poison of active sites. As results, Ru-Sn/SnO2 NS display remarkable alkaline HER performance with an extremely low overpotential (12mV at 10mA cm-2) and robust stability (650h), much superior to those of Ru NS (27mV at 10mA cm-2 with 90h stability) and Ru-Sn NS (16mV at 10mA cm-2 with 120h stability). The work sheds new light on designing of efficient alkaline HER electrocatalyst.

Electronic Communication between Co and Ru Sites Decorated on Nitrogen-doped Carbon Nanotubes Boost the Alkaline Hydrogen Evolution Reaction

Electronic Communication between Co and Ru Sites Decorated on Nitrogen-doped Carbon Nanotubes Boost the Alkaline Hydrogen Evolution Reaction

Manipulating d-Band Center of Nickel by Single-Iodine-Atom Strategy for Boosted Alkaline Hydrogen Evolution Reaction.

Ni-based electrocatalysts have been predicted as highly potential candidates for hydrogen evolution reaction (HER); however, their applicability is hindered by an unfavorable d-band energy level (Ed). Moreover, precise d-band structural engineering of Ni-based materials is deterred by appropriative synthesis methods and experimental characterization. Herein, we meticulously synthesize a special single-iodine-atom structure (I-Ni@C) and characterize the Ed manipulation via resonant inelastic X-ray scattering (RIXS) spectroscopy to fill this gap. The complex catalytic mechanism has been elucidated via synchrotron radiation-based multitechniques (SRMS) including X-ray absorption fine structure (XAFS), in situ synchrotron radiation-based Fourier transform infrared (SR-FTIR) spectroscopy, and near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). In particular, RIXS is innovatively applied to reveal the precise regulation of Ni Ed of I-Ni@C. Consequently, the role of such single-iodine-atom strategy is confirmed to not only facilitate the moderate Ed of the Ni site for balancing the adsorption/desorption capacities of key intermediates but also act as a bridge to enhance the electronic interaction between Ni and the carbon shell for forming a localized polarized electric field conducive to H2O dissociation. As a result, I-Ni@C exhibits an enhanced alkaline hydrogen evolution performance with an overpotential of 78 mV at 10 mA/cm2 and superior stability, surpassing the majority of the reported Ni-based catalysts. Overall, this study has managed to successfully tailor the d-band center of materials from the SRMS perspective, which has crucial implications for nanotechnology, chemistry, catalysis, and other fields.

A "Two-Pronged" Strategy to Boost Hydrogen Evolution Kinetics on NiFe-Based (Oxy)hydroxides via Oxygen Deficient Ni-Mo-Fe Coordinate Structures for Ultra-Stable Ampere-Level Alkaline Overall Water Splitting.

NiFe (oxy)hydroxides have been regarded as one of the state-of-the-art catalysts for oxygen evolution reaction (OER). Unfortunately, the sluggish hydrogen evolution reaction (HER) kinetics limit its application as bifunctional electrocatalyst for alkaline overall water splitting (OWS). Herein, a "two-pronged" strategy is proposed to construct highly active oxygen deficient Ni-Mo-Fe coordinate structures in NiFe (oxy)hydroxide (NFM-OVR/NF), which simultaneously reduces the energy barrier of Volmer and Heyrovsky steps during alkaline HER process and significantly accelerate the reaction kinetics. Consequently, NFM-OVR/NF delivers overpotentials as low as 25 and 234mV to achieve 10 and 1000mA cm-2 in 1.0M KOH, respectively. Furthermore, benefiting from excellent HER and OER activity, NFM-OVR/NF exhibits a remarkable OWS activity with cell voltages of 1.44V and 1.77V at 10 and 1000mA cm-2 in 1.0M KOH, and displays ultralong-term stability for 600h at 500mA cm-2, while remaining durable for 300h in an alkaline water electrolyzer in 30% KOH at 80°C. The calculated price per gallon of gasoline equivalent for the produced H2 is $ 0.92, which is much lower than 2026 U.S. Department of Energy target ($ 2.00), demonstrating feasibility and practicability of NFM-OVR/NF for industrial applications.

Hydrogen Evolution Reactivity of Pentagonal Carbon Rings and p-d Orbital Hybridization Effect with Ru.

Topological defects are inevitable existence in carbon-based frameworks, but their intrinsic electrocatalytic activity and mechanism remain under-explored. Herein, the hydrogen evolution reaction (HER) of pentagonal carbon-rings is probed by constructing pentagonal ring-rich carbon (PRC), with optimized electronic structures and higher HER activity relative to common hexagonal carbon (HC). Furthermore, to improve the reactivity, we couple Ru clusters with PRC (Ru@PRC) through p-d orbital hybridization between C and Ru atoms, which drives a shortcut transfer of electrons from Ru clusters to pentagonal rings. The electron-deficient Ru species leads to a notable negative shift in d-band centers of Ru and weakens their binding strength with hydrogen intermediates, thus enhancing the HER activity in different pH media. Especially, at a current density of 10 mA cm-2, PRC greatly reduces alkaline HER overpotentials from 540 to 380 mV. And Ru@PRC even exhibits low overpotentials of 28 and 275 mV to reach current densities of 10 and 1000 mA cm-2, respectively. Impressively, the mass activity and price activity of Ru@PRC are 7.83 and 15.7 times higher than that of Pt/C at the overpotential of 50 mV. Our data unveil the positive HER reactivity of pentagonal defects and good application prospects.

Navigating Alkaline Hydrogen Evolution Reaction Descriptors for Electrocatalyst Design

The quest for efficient green hydrogen production through Alkaline Water Electrolysis (AWE) is a critical aspect of the clean energy transition. The hydrogen evolution reaction (HER) in alkaline media is central to this process, with the performance of electrocatalysts being a determining factor for overall efficiency. Theoretical studies using energy-based descriptors are essential for designing high-performance alkaline HER electrocatalysts. This review summarizes various descriptors, including water adsorption energy, water dissociation barrier, and Gibbs free energy changes of hydrogen and hydroxyl adsorption. Examples of how to apply these descriptors to identify the active site of materials and better design high-performance alkaline HER electrocatalysts are provided, highlighting the previously underappreciated role of hydroxyl adsorption-free energy changes. As research progresses, integrating these descriptors with experimental data will be paramount in advancing AWE technology for sustainable hydrogen production.