Electrocatalytic Hydrogen Production Research Articles

Vertically aligned ReS2 on MOF deorived CoS2–C hybrid as core-shell catalyst for promoting overall water splitting

The rational design of a core-shell structured electrocatalyst is important to improve the efficiency of electrocatalytic hydrogen production through water splitting. Herein, the catalyst is composed of rhenium disulfides (ReS2) vertically grown on cobalt sulfides/carbon hybrid by hydrothermal and activation treatment (CoS2–C@ReS2/CFP). The core-shell structure is constructed by sulfurizing the cobalt-based metal-organic framework, preventing the restacking of the ReS2 nanosheet, exposing more active sites, and facilitate electrolyte ion diffusion. Moreover, the CoS2–C@ReS2/CFP catalyst shows exceptional performance during the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) process in an alkaline electrolyte. At ·10 mA cm−2, the overpotentials of the CoS2–C@ReS2/CFP catalyst are 85 and 257 mV during the HER and OER processes with the small Tafel slope, low charge transfer resistance and exceptional catalytic stability. The combination of the CoS2 core and ReS2 shell is designed to adjust the adsorption energy of water molecules, promoting water dissociation, and enhancing the catalytic activity of CoS2–C@ReS2/CFP catalyst. This work provides an efficient strategy for developing the core-shell structured catalysts, potentially advancing the practical application into water splitting for hydrogen production.

Heterojunction engineering via in-situ electrochemical reconstruction for boosting electrocatalytic biomass upgrading-coupled hydrogen production

Rationally designing and constructing high-performance electrocatalysts is critical for environmental and sustainable electrocatalytic biomass upgrading coupled with hydrogen evolution. Herein, we developed a novel in-situ electrochemical reconstruction strategy to fabricate heterostructured electrocatalysts for efficient biomass upgrading-coupled hydrogen production. Through in-situ anodic and cathodic electrochemical reconstructions, Ni(OH)2-CuO nanorods assembled by nanosheets with abundant low-crystalline Ni(OH)2/crystalline CuO heterojunctions on Cu foam (Ni(OH)2-CuO/CF) and S-doped Ni(OH)2-Cu2O nanofoam formed by cross-linked nanoparticles on CF (Ni(OH)2-Cu2O(S)/CF) were respectively constructed for electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) and hydrogen evolution reaction (HER). For the Ni(OH)2-CuO/CF, the overall configuration of nanorods assembled by self-standing nanosheets ensures good conductivity, full exposure of active sites, and fast mass/electron transfer. The abundant Ni(OH)2/CuO heterojunctions provide dual active sites of Ni and Cu to simultaneously adsorb and activate hydroxyl and aldehyde groups in HMF. The electronic interaction between Ni(OH)2 and CuO accelerates the reversible conversion of Ni2+↔Ni3+ to generate more Ni3+ active species and enhances the intrinsic activity of dual active sites to reduce the reaction energy barrier of the rate-determining step. As a result, the Ni(OH)2-CuO/CF shows superior HMFOR performance, with a HMF conversion of 99.3%, a FDCA yield of 98.1%, and stability for 50 cycles in 10 mM HMF+1.0 M KOH medium. Meanwhile, the Ni(OH)2-Cu2O(S)/CF also exhibits remarkable HER activity with an overpotential of only 64.7 mV at 10 mA cm−2 in 1.0 M KOH solution due to its unique structure and composition. When coupling a two-electrode system, the HMFOR-HER system achieves a current density of 10 mA cm−2 at 1.44 V, 221 mV lower than that of the OER-HER system. This work provides an in-situ electrochemical reconstruction strategy for designing advanced heterojunction-rich electrocatalysts for various electrocatalytic applications.

Heterophase Intermetallic Compounds for Electrocatalytic Hydrogen Production at Industrial-Scale Current Densities.

Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.

A Review of the Structure–Property Relationship of Nickel Phosphides in Hydrogen Production

Hydrogen, one of the most promising forms of new energy sources, due to its high energy density, low emissions, and potential to decarbonize various sectors, has attracted significant research attention. It is known that electrocatalytic hydrogen production is one of the most widely investigated research directions due to its high efficiency in the conversion of electricity to H2 gas. However, given the limited reserves and high cost of precious metals, the search for non-precious metal-based catalysts has been widely explored, for example, transition metal phosphides, oxides, and sulfides. Despite this interest, a detailed survey unveils that the surface and internal structures of the alternative catalysts, including their surface reconstruction, composition, and electronic structure, are poorly studied. As a result, a disconnection in the structure–property relationship severely hinders the rational design of efficient and reliable non-precious metal-based catalysts. In this review, by focusing on Ni5P4, a bifunctional catalyst for water splitting, we systematically summarize the material motifs pertaining to the different synthetic methods, surface characteristics, and hydrolysis properties. It is believed that a cascaded correlation may provide insights toward understanding the fundamental catalytic mechanism and design of robust alternative catalysts for hydrogen production.

Electrochemical Reforming of Methanol using Multilayer Nanoarchitectonics with Ligand Exchange-Induced Layer-by-Layer Assembly toward Electrocatalytic Hydrogen Production

Electrochemical Reforming of Methanol using Multilayer Nanoarchitectonics with Ligand Exchange-Induced Layer-by-Layer Assembly toward Electrocatalytic Hydrogen Production

Size engineering of porous CuWO4–CuO heterojunction for enhanced hydrogen evolution in alkaline media

Constructing electrocatalysts with heterogeneous interfaces is of great significance for improving the performance of electrocatalytic hydrogen production. In this work, CuWO4·2H2O–CuO (P-CWOC) was synthesized by hydrothermal method, and spherical porous CuWO4–CuO (CWOC) was obtained through annealing treatment. The size of CuWO4–CuO can be controlled from 72 to 221 nm by regulating the supersaturation of the solution. Among them, CuWO4–CuO with a particle size of 72 nm (CWOC-72) possesses the most oxygen vacancies and the largest specific surface area. The W atom in the heterostructure of CuWO4 and CuO can affect the electronic structure of Cu atoms, and the presence of oxygen vacancies is beneficial for increasing the surface oxygen affinity of the composite material. Benefitting from the largest number of oxygen vacancies and the largest specific surface area, the CWOC-72 own the best catalytic performance compared to the other four catalysts. The overpotential at a current density of 10 mA cm−2 is 121 mV, and the Tafel slope is 70 mV·dec−1. Its excellent stability was confirmed by chronoamperometry, in-situ XRD, and in-situ Raman spectroscopy, and its alkaline HER performance is superior to most CuO-based catalysts.

Vacancy controlled MoSSe/MnSe heterostructure show boosting activities in photoelectrochemical and electrocatalytic hydrogen production

There are many factors that affect the activity of catalyst, such as the absorption capacity of catalyst itself, carrier separation, active site and surface transfer efficiency. In the study of this paper, two main influencing factors of catalyst are considered. One is that the electronic band structure determines the carrier separation and transport efficiency; the other is surface chemical state affects the active sites. A vacancy controlled MoSSe/MnSe heterojunction catalyst was demonstrated: MoSSe formed a type II heterojunction with MnSe, allowing photo generated carriers to move between the conduction and valence bands of the two semiconductors, thereby improving separation efficiency. Under the optimized MnSe composite ratio, MSMS3 exhibited a photocurrent density of up to −7.153 mA/cm2 at 0 V vs RHE, which is 5.2 times that of the MoSSe. In addition, the catalyst was further treated with ethylene diamine tetraacetic acid (EDTA). Due to the weak binding between Mn and Se, a large number of Mn atoms detach and form many Mn vacancies (VMn) on the catalyst surface due to the complexation effect of EDTA. These vacancies provide a large number of active sites, reduce of the adsorption energy barrier for H* which greatly enhancing the activity of the catalyst in hydrogen evolution reactions. Compared with the original MoSSe (overpotential 476 mV, Tafel slope 216 mV/dec), the overpotential of the vacancy catalyst MSMS3v is reduced to 197 mV with a Tafel slope of 77 mV/dec. This work demonstrates a novel catalyst regulation strategy.

Structural optimization and electrocatalytic hydrogen production performance of carbon-based composites: A mini-review

The energy demand has increased significantly in recent years and it is urgent to develop a renewable energy system that is highly efficient and non-noble metal-based. Hydrogen energy is an environmentally friendly energy source with abundant resources, which can be used to solve the problem of high energy demand without greenhouse gas emissions. However, the development of catalysts for hydrogen production technology by electrolysis of water is slow, mainly due to the complexity of the electrolysis hydrogen generation process, low hydrogen production efficiency, weak electrode material activity and high cost. Among the non-noble metal-based catalysts, carbon-based materials have high conductivity, tunable chemical bonding, and easily modified morphology, making them beneficial to achieving efficient hydrogen production, though pure carbon composites suffer from few surface-active sites and unmoderated hydrogen bonding energy, which need to be further optimized. The principle of electrocatalytic hydrogen production from the perspectives of reaction thermodynamics and kinetics is analyzed and discussed in this paper. Thermodynamics of electrocatalytic hydrogen production is reflected by the Gibbs free energy of hydrogen adsorption (ΔGH*) and electrode potential (E). Reaction kinetics of the electrocatalytic hydrogen production process are reflected by overpotential, Tafel slope and exchange current density. Structural optimization methods of carbon-based composite materials and hydrogen production performance after structural optimization are also summarized. Structural optimization methods of carbon-based composite materials mainly include introducing active sites, improving conductivity, increasing specific surface area and introducing self-supporting materials. Finally, prospects are proposed for the development direction and existing problems of electrocatalytic hydrogen production performance of carbon-based composites.

The Electrochemical Hydrogen Evolution Reaction Based on Helical Chain Stacked 2D Tellurium Nanoflakes

AbstractA crucial factor in advancing the broad utilization of electrocatalytic hydrogen evolution reaction (HER) is the development of efficient catalysts with sufficient active sites. Herein, a hydrothermal approach is utilized to fabricate helical chain stacked two‐dimensional (2D) tellurium (Te) nanoflakes, whose HER performance hasn't been systematically studied yet. It is found that Te nanoflakes transferred on carbon fiber paper (CFP) exhibit impressive HER properties and show a load dependence. The overpotential required for HER is significantly reduced to 279 mV under a load condition of 0.86 mg cm−2 at a current density of 10 mA cm−2. Density functional theory (DFT) calculations are further systematically carried out on Te catalytic sites along the helical chain at [0001] direction with a threefold screw symmetry. It is found that the Gibbs free energy of adsorbed hydrogen atom (ΔGH*) on Te sites is significantly lower than that of molybdenum disulfide (MoS2). Besides, the active sites based on surface atom density calculation reveal that Te provides more adsorption sites than layered MoS2. The decreased adsorption energy and efficient adsorption sites in Te may highlight the promising application of elemental crystal Te in electrocatalytic hydrogen production and pave the way for developing new types of electrocatalysts.

Heterostructured NiMo-sulfide micro-pillar arrays for advanced alkaline electrocatalytic clean hydrogen production via overall water splitting

Transition metals doped molybdenum sulfide/oxide present themselves as capable for hydrogen evolution reaction (HER), because of their exceptional chemical and physical properties. In this study, we introduce a strategy for synthesizing molybdenum-based binary sulfide/oxide heterostructures using a hydrothermal method. An electrochemical investigation revealed the pivotal role of NiMo-sulfide in achieving remarkable bifunctional electrocatalytic activity, resulting in a current density of −50 mA cm−2 at an overpotential of 174 mV for HER. The excellent reaction kinetics were evident from the low Tafel slope of 116.8 mVdec−1. The electrolyzer showcased outstanding performance, with the best-performing NiMo-sulfide and benchmark RuO2 at the anode. It achieved a low cell potential of 1.60 V to reach 10 mA cm−2, exhibited remarkable durability for 100 h, and demonstrated promise for water splitting with a Faradaic efficiency of 94 and 89 % for O2 and H2 evolution respectively. Furthermore, the electrolyzer displayed potential for large-scale hydrogen production by attaining an industrially appropriate current density of 800 mA cm−2 at a cell potential of 2.24 V. This study also highlights the latest advancements in electrodialysis to enhance the catalytic activity of electrode materials.

Activating TiO2 through the Phase Transition-Mediated Hydrogen Spillover to Outperform Pt for Electrocatalytic pH-Universal Hydrogen Evolution.

Endowing conventional materials with specific functions that are hardly available is invariably of significant importance but greatly challenging. TiO2 is proven to be highly active for the photocatalytic hydrogen evolution while intrinsically inert for electrocatalytic hydrogen evolution reaction (HER) due to its poor electrical conductivity and unfavorable hydrogen adsorption/desorption behavior. Herein, the first activation of inert TiO2 for electrocatalytic HER is demonstrated by synergistically modulating the positions of d-band center and triggering hydrogen spillover through the dual doping-induced partial phase transition. The N, F co-doping-induced partial phase transition from anatase to rutile phase in TiO2 (AR-TiO2|(N,F)) exhibits extraordinary HER performance with overpotentials of 74, 80, and 142 mV at a current density of 10 mA cm-2 in 1.0 M KOH, 0.5 M H2SO4, and 1.0 M phosphate-buffered saline electrolytes, respectively, which are substantially better than pure TiO2, and even superior to the benchmark Pt/C catalysts. These findings may open a new avenue for the development of low-cost alternative to noble metal catalysts for electrocatalytic hydrogen production.

Polyoxometalate and ammonium polyphosphate induced bimetallic tungsten-based phosphides for electrocatalytic hydrogen production

Tungsten-based phosphide has gained significant traction in the field of electrocatalytic hydrogen evolution on account of its platinum-like characteristics, cost-effectiveness and exceptional electrical conductivity. In this work, bimetallic phosphide (WP/WCoP2@C) was prepared for hydrogen evolution reaction (HER) via high-temperature annealing and in situ phosphating procedure using the green phosphorus source ammonium polyphosphate (APP) without no toxic substances generated. WP/WCoP2@C exhibits satisfactory catalytic hydrogen evolution activity, with the overpotentials in acidic and alkaline environments of 151 and 138 mV, respectively, at current density reaching 10 mV cm−2. Moreover, WP/WCoP2@C shows favorable stability in the acid-base electrolytes for 36 h. This work provides experimental ideas for the green clean synthesis of tungsten-based phosphides for electrochemical small molecules transformation for sustainable energy generation.

Activating Interfacial Electron Redistribution in Lattice-Matched Biphasic Ni3N-Co3N for Energy-Efficient Electrocatalytic Hydrogen Production via Coupled Hydrazine Degradation.

The development of high-purity and high-energy-density green hydrogen through water electrolysis holds immense promise, but issues such as electrocatalyst costs and power consumption have hampered its practical application. In this study, we present a promising solution to these challenges through the use of a high-performance bifunctional electrocatalyst for energy-efficient hydrogen production via coupled hydrazine degradation. The biphasic metal nitrides with highly lattice-matched structures are deliberately constructed, forming an enhanced local electric field between the electron-rich Ni3N and electron-deficient Co3N. Additionally, Mn is introduced as an electric field engine to further activate electron redistribution. Our Mn@Ni3N-Co3N/NF bifunctional electrocatalyst achieves industrial-grade current densities of 500 mA cm-2 at 0.49 V without degradation, saving at least 53.3 % energy consumption compared to conventional alkaline water electrolysis. This work will stimulate the further development of metal nitride electrocatalysts and also provide new perspectives on low-cost hydrogen production and environmental protection.

Effect of molybdenum doping Zn-Co spinel oxide microspheres for efficient electrocatalytic hydrogen production in alkaline media and study supported by DFT

The rational design of efficient transition metal-based electrocatalysts for the hydrogen evolution reaction (HER) is critical for the water-splitting process. Industrial water-alkali electrolysis requires large current densities at low overpotentials, which are always limited by the intrinsic activity. Here, ZnCo2−xMoxO4 (x ≤ 0.10) spinel oxide microsphere electrocatalysts were synthesized for the process in alkaline media. Mo doping in the ZnCo2O4 crystal structure enhanced the active sites, which were responsible for the enhancement in the HER process. The ZnCo2−xMoxO4 (x = 0.06) electrocatalyst exhibited exceptional HER activity, as evidenced by an overpotential of 195 mV, Tafel slope of 81.4 mVs−1 and high stability for 40 h with 1000 cycles linear sweep voltammetry. The surface and electrochemical characterization revealed that 6% Mo-doping exhibits improved the HER activity due to a significantly higher electrochemical surface area and accelerated charge transfer kinetics at the semiconductor electrolyte interface. Density functional theory (DFT) for exploring and explaining the effect of the Mo dopants on the HER activity elucidated that hydrogen and water molecules are adsorbed on the surface of the Mo-doped ZnCo2O4 slab structures. The results show that Mo dopants enhance the chemical activity, due to water adsorption, and HER activity for enhanced electrocatalytic processes. This work provides a new insight into low-metal-cost materials for efficient and durable HER electrocatalysts and successfully showcases the catalyst model for a detailed mechanistic insight into the HER process.

Enhancing the stability of NiFe-layered double hydroxide nanosheet array for alkaline seawater oxidation by Ce doping

Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation. Nevertheless, the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry. Herein, we present our recent discovery that the incorporation of Ce into NiFe layered double hydroxide nanosheet array on Ni foam (Ce-NiFe LDH/NF) emerges as a robust electrocatalyst for seawater oxidation. During the seawater oxidation process, CeO2 is generated, effectively repelling Cl− and inhibiting the formation of ClO−, resulting in a notable enhancement in the oxidation activity and stability of alkaline seawater. The prepared Ce-NiFe LDH/NF requires only overpotential of 390 mV to achieve the current density of 1 A cm−2, while maintaining long-term stability for 500 h, outperforming the performance of NiFe LDH/NF (430 mV, 150 h) by a significant margin. This study highlights the effectiveness of a Ce-doping strategy in augmenting the activity and stability of materials based on NiFe LDH in seawater electrolysis for oxygen evolution.

Recent strategies for improving the catalytic activity of ultrathin transition metal sulfide nanosheets toward the oxygen evolution reaction

Hydrogen is considered as one of the clean secondary energy sources required in industry and daily life. Electrocatalytic hydrogen production is believed to be the most reliable method for converting renewable energy into chemical energy. Two-dimensional (2D) transition metal disulfides (TMDs), as an emerging electrocatalysts, have been widely investigated for oxygen evolution reaction (OER) in water splitting. Herein, this review summarizes the recent progress and the strategies of ultrathin TMDs for improving the OER electrocatalytic activities. The basic catalytic mechanism of OER is first introduced, and then the catalytic characteristics of 2D TMDs are presented. Importantly, this review specifically concentrates on strategies to improve catalytic activity such as phase engineering, defect/vacancy engineering, heterostructure, doping effect, and catalyst support material. It can be concluded that these regulatory strategies can largely enhance the electrocatalytic performance by increasing the active site exposure and improving the electrocatalytic kinetics. In addition, the challenges and perspectives of 2D TMDs catalysts are presented, which offers valuable guidance in designing efficient and low-cost OER electrocatalysts for future energy applications. We hope that this review will inspire future studies and bridge the gap between strategy design and practical application.

Dual-strategy engineered nickel phosphide for achieving efficient hydrazine-assisted hydrogen production in seawater

The electrocatalytic hydrogen production in seawater without freshwater shortage pressure is promising, but hindered by tardy oxygen evolution reaction and detrimental chloride electrochemistry. Herein, dual-strategy of Fe-doping and CeO2-decorating into...

Engineering ultrafine PtIr alloy nanoparticles into porous nanobowls via a reactive template-engaged assembly strategy for high-performance electrocatalytic hydrogen production

We demonstrate self-sacrificial templated strategy for the synthesis of hollow and porous PtIr alloyed nanobowls composed of ultrafine nanoparticles and the resulting self-supported Pt7Ir NBs exhibit superior HER performance.

A hierarchical carbon foam-hosted Co2P nanoparticles monolithic electrode for ampere-level and super-durable electrocatalytic hydrogen production.

In this work, we develop a hierarchical carbon foam-based monolithic electrode (Co2P@HCF) from Co2+-adsorbed polyvinyl alcohol (PVA) sponge via the successive carbonization and phosphorization. Owing to the 3D hierarchical porous structure, excellent electrolyte wettability, good mechanical strength, and intimate embedding of highly dispersed Co2P nanoparticles, the Co2P@HCF electrode delivers a high current density of 1.0 A cm-2 for the hydrogen evolution reaction (HER) at ultralow overpotentials of 189.6 and 218.6 mV in 0.5 M H2SO4 and 1.0 M KOH solutions, respectively, with remarkable durability for 100 h.

Vacancy induced microstrain in high-entropy alloy film for sustainable hydrogen production under universal pH conditions

Electrocatalytic hydrogen production plays an essential role in generating eco-friendly fuels for energy storage and transportation within a sustainable energy framework. High-entropy alloys (HEAs), with their abundant compositional variety, significantly...