Catalysts For Hydrogen Evolution Research Articles

CoFe-Layered Double Hydroxide Needles on MoS2/Ni3S2 Nanoarrays for Applications as Catalysts for Hydrogen Evolution and Oxidation of Organic Chemicals

CoFe-Layered Double Hydroxide Needles on MoS₂/Ni₃S₂ Nanoarrays for Applications as Catalysts for Hydrogen Evolution and Oxidation of Organic Chemicals

A general strategy for the enhanced H2 production performance of CdS/noble metal sulfide nanorods photocatalysts by cation exchange

In this work, we report a series of noble metal (Ag, Au, Pt, etc.) sulfides that act as co-catalysts anchoring on CdS nanorods (NRs) obtained via a cation exchange strategy to promote photocatalytic hydrogen evolution. CdS NRs are first generated via a hydrothermal routine, noble metal sulfides are then in-situ grown on CdS NRs by a cation exchange method. CdS/Ag2S, CdS/Au2S and CdS/PtS NRs show improved hydrogen production rates (2506.88, 1513.17 and 1004.54 μmol g−1h−1, respectively), approximately 18, 11 and 7 times higher than CdS NRs (138.27 μmol g−1h−1). Among CdS/noble metal sulfide NRs, CdS/Ag2S NRs present the best H2 production performance. The apparent quantum efficiency (AQE) of CdS/Ag2S NRs achieves 3.11 % at λ = 370 nm. The improved photocatalytic performance of CdS/noble metal sulfide NRs dues to the following points: i) Noble metal sulfides on CdS NRs are beneficial for elevating light-absorbing and light-utilizing capacities, contributing to generating more photoexcited charges; ii) Noble metal sulfides are in-situ grown on CdS NRs as electron acceptors by a cation exchange method, thus the photoexcited electrons generated by CdS NRs rapidly migrate to the surface of noble metal sulfides, successfully accelerating the carriers separation efficiency. This series of noble metal sulfides acting as co-catalysts anchoring on CdS NRs offer new insights into the construction principles of high-performance photocatalytic hydrogen evolution catalysts.

Oxygen Vacancy and Heterostructure Modulation of Co2P/Fe2P Electrocatalysts for Improving Total Water Splitting.

Designing a stable and highly active catalyst for hydrogen evolution and oxygen evolution reactions (HER/OER) is essential for the industrialization of hydrogen energy but remains a major challenge. This work reports a simple approach to fabricating coupled Co2P/Fe2P nanorod array catalyst for overall water decomposition, demonstrating the source of excellent activity in the catalytic process. Under alkaline conditions, Co2P/Fe2P heterostructures exhibit an overpotential of 96 and 220 mV for HER and OER, respectively, at 10 mA cm-2. For total water splitting, a low voltage of 1.56 V is required to provide a current density of 10 mA cm-2. And the catalyst exhibits long-term durability for 30 h at a high current density of 250 mA cm-2. The analysis of the results revealed that the presence of interfacial oxygen vacancies and the strong interaction between Co2P/Fe2P provided the catalyst with more electrochemically active sites and a faster charge transfer capability, which improved the hydrolysis dissociation process. Electrochemically active metal (oxygen) hydroxide phases were produced after OER stability testing. The results of this study prove its great potential in practical industrial electrolysis and provide a reasonable and feasible strategy for the design of nonprecious metal phosphide electrocatalysts.

Porous MoP2/MoS2 hierarchical nanowires for efficient hydrogen evolution reaction in full pH range

Rational designing Mo-based heterojunction catalysts as hydrogen evolution catalysts is seriously significant for the widespread utilization of hydrogen energy. Here, the ingenious hierarchical construction of MoP2/MoS2 nanowires was delivered with high conductivity of porous MoP2 and abundant active sites of defect-rich MoS2. Under synergistic effect of two materials, this catalyst achieves a dramatically optimized electronic structure to boost hydrogen evolution in all-pH range. The optimal MoP2/MoS2/CC nanoreactor showed overpotentials of 47.11, 60.16, and 89.83 mV to drive −10 mA cm−2 and Tafel slopes of 51.69, 52.04, and 73.79 mV dec−1 in acidic, alkaline, and neutral media, respectively. This finding may provide an effective approach for elevating the pH-universal electrocatalytic performance in order to achieve industrial hydrogen evolution.

Ni/WS2/WC Composite Nanosheets as an Efficient Catalyst for Photoelectrochemical Hydrogen Peroxide Sensing and Hydrogen Evolution.

It is highly attractive to develop a photoelectrochemical (PEC) sensing platform based on a non-noble-metal nano array architecture. In this paper, a PEC hydrogen peroxide (H2O2) biosensor based on Ni/WS2/WC heterostructures was synthesized by a facile hydrothermal synthesis method and melamine carbonization process. The morphology, structural and composition and light absorption properties of the Ni/WS2/WC catalyst were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer. The average size of the Ni/WS2/WC nanosheets was about 200 nm. Additionally, the electrochemical properties toward H2O2 were studied using an electrochemical workstation. Benefiting from the Ni and C atoms, the optimized Ni/WS2/WC catalyst showed superior H2O2 sensing performance and a large photocurrent response. It was found that the detection sensitivity of the Ni/WS2/WC catalyst was 25.7 μA/cm2/mM, and the detection limit was 0.3 mmol/L in the linear range of 1-10 mM. Simultaneously, the synthesized Ni/WS2/WC electrode displayed excellent electrocatalytic properties in hydrogen evolution reaction (HER), with a relatively small overpotential of 126 mV at 10 mA/cm2 in 0.5 M H2SO4. This novel Ni/WS2/WC electrode may provide new insights into preparing other efficient hybrid photoelectrodes for PEC applications.

NiCoP fibers as novel catalysts for hydrogen evolution in alkali and acidic environment

NiCoP transition metal phosphide has been recognized as a most promising candidate to alternate the noble metals in hydrogen evolution reaction. Herein, it is first time presented the facile preparation of NiCoP electrocatalyst in form of fibers with dominant 1D structure formed by needle-less electrospinning technology and finalized by defined heat treatment process. The study provides a precise method for the preparation of NiCoP or similar phosphide fibers, together with an experimental proof of their excellent electrocatalytic performance in alkali and acidic environments. The as-prepared fibrous NiCoP electrocatalyst sintered in air at 900 °C followed by sintering at 700 °C in Ar/H2 exhibits low hydrogen evolution reaction overpotential (η10) of 141 mV in alkali and 146 mV in acidic environment corresponding with low Tafel slopes of 53 and 97.8 mV/dec, respectively. The bimetallic phosphide also shows superior oxygen evolution reaction activity in alkaline medium 1 M KOH with satisfying durability in long-term stability tests. The highly innovative fibrous form of the material not only plays a significant role in regulation of the electronic structure and boosting the electrochemical active sites and thus the electrocatalytic performance in water splitting technology, but also allows tuning of the electrode electric conductivity, occurrence of the active sites probability and thus utilisation of the electrode, together with its permeability and mechanical stability.

Preparation of chromium barium oxide catalysts for hydrogen evolution from sodium borohydride methanolysis

This paper describes the synthesis of Cr2O3, Cr1.7Ba0.3O3, and Cr1.4Ba0.6O3 nanoparticles as catalysts to enhance hydrogen evolution in sodium borohydride methanolysis. Various characterization techniques, comprising X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and others were utilized to characterize the prepared nanoparticles. The XRD analysis showed that the formed Cr2O3 exhibits a hexagonal crystal structure, with an estimated mean crystallite size of 24 nm. SEM micrographs showed nanoparticles with homogeneous distributions, exhibiting spherical or distorted spherical shapes. XPS analysis showed that all synthetic Cr2-xBaxO3 materials consist of Cr, O, and the presence of Ba for doped samples. The energy gap for pure Cr2O3 nanoparticles was determined to be 3.28 eV. Inclusion of Ba into the Cr2O3 nanostructure modified the band gap, resulting in values of 2.8 and 1.5 eV at 15 % and 30 % barium content. The hydrogen production rate from NaBH4 methanolysis for Cr2O3, Cr1.7Ba0.3O3, and Cr1.4Ba0.6O3 catalysts were 5984, 31176 and 11913 mL/g.min, respectively.

MXene supported PtCo bimetallic catalyst for hydrogen evolution in acidic conditions

MXene supported PtCo bimetallic catalyst for hydrogen evolution in acidic conditions

ZIF-8 induced N, P double doped porous molybdenum phosphide hydrogen evolution catalyst

Molybdenum based phosphides have gradually become the investigation frontier of hydrogen evolution catalysts due to the platinum like electronic structure. In this paper, N, P double-doped graphite carbon layers wrapped with MoP nanoparticles (P–MoP@NPC), is directly compounded by one-step high-temperature carboning PMo12-APP@ZIF-8 precursor. P–MoP@NPC possesses splendid hydrogen production reactive, in two kinds of electrolytes, when the overpotentials of P–MoP@NPC are 132 mV and 161 mV, the slope of current density reaching 10 mA cm−2, Tafel slope are 67 and 79 mV dec−1, respectively. In the bargain, P–MoP@NPC displays satisfactory durability in acid and alkaline mediums and can continue to work for more than 24 h. The wonderful hydrogen production ability of P–MoP@NPC is ascribed to the synergistic effect of MoP nanoparticles, hierarchical porous structure as well as N, P double-doped carbon layers. The confinement effect of ZIF-8 makes most of the synthesized MoP nanoparticles evenly distributed. The hierarchical porous structure caused by the volatilization of Zn atoms with high temperature can expose more active centers. The N, P double-doped graphitic carbon layers not only protect the catalyst but also adjust the electronic structure of MoP, promoting the hydrogen production capacity. This work may provide a general way to study molybdenum phosphide catalysts synthesized by APP as a green phosphorus source for energy conversion.

Application of graphdiyne for promote efficient photocatalytic hydrogen evolution

The photocatalytic hydrogen evolution technology converts solar energy into clean and environmentally friendly hydrogen energy, which is considered an effective means to solve environmental pollution and energy crisis. The unique sp and sp2 hybrid carbon network structure of graphdiyne endows it with excellent carrier mobility, and high porosity, making it a promising photocatalytic material for solar energy conversion. This article provides a detailed description of the unique structural properties and adjustable bandgap of graphdiyne. In addition, a detailed review was provided on the modification strategies of graphdiyne based catalysts for photocatalytic hydrogen evolution, including titanium based photocatalysts, metal oxide photocatalysts, double hydroxide catalysts, metal organic framework photocatalysts and other typical semiconductors. Finally, the challenges and opportunities for developing graphdiyne semiconductors for photocatalytic water splitting were proposed. Timely review is expected to contribute to the rapid development of graphdiyne in the field of photocatalytic hydrogen evolution.

Polyaniline nanowires decorated nickel phosphides hollow spheres hydrogen evolution catalyst for proton exchange membrane electrolysis

Cost-competitive proton exchange membrane water electrolyzer (PEMWE) requires efficient and earth-abundant electrocatalyst to replace Platinum for hydrogen evolution reaction (HER). We report here a polyaniline (PANI) nanowires decorated Ni2P hollow spheres catalyst and its exceptional activity toward HER in 0.5 M H2SO4 aqueous and PEMWE. The excellent catalytic activity of HER originates from unique hybrid structure of PANI/Ni2P with good conductivity, decent surface activity and optimal porous property. As a cheaper alternative to Pt/C, we used PANI/Ni2P as the cathode to set a PEMWE cell (Nafion® 117 membrane), the cell showed a current density of 1.0 A cm−2 at 1.822 V and 2.0 A cm−2 at 2.026 V, which is comparable with Pt/C (1.778 V at 1.0 A cm−2, and 2.086 V at 2.0 A cm−2). Our catalyst maintained a stable performance in a PEM electrolysis at a current density of 1.0 A cm−2 with the temperature of 80 °C, and preserved surface morphology and electron state well after 320 h continuous electrolysis. This study offers PANI/Ni2P HER catalyst as a cheaper replacement for Pt/C in PEMWE and provides a new insight to design earth-abundant catalysts for HER.

Pt Single Atoms Supported on Defect Ceria as an Active and Stable Dual-Site Catalyst for Alkaline Hydrogen Evolution.

This work evaluates the feasibility of alkaline hydrogen evolution reaction (HER) using Pt single-atoms (1.0 wt %) on defect-rich ceria (Pt1/CeOx) as an active and stable dual-site catalyst. The catalyst displayed a low overpotential and a small Tafel slope in an alkaline medium. Moreover, Pt1/CeOx presented a high mass activity and excellent durability, competing with those of the commercial Pt/C (20 wt %). In this picture, the defective CeOx is active for water adsorption and dissociation to create H* intermediates, providing the first site where the reaction occurs. The H* intermediate species then migrate to adsorb and react on the Pt2+ isolated atoms, the site where H2 is formed and released. DFT calculations were also performed to obtain mechanistic insight on the Pt1/CeOx catalyst for the HER. The results indicate a new possibility to improve the state-of-the-art alkaline HER catalysts via a combined effect of the O vacancies on the ceria support and Pt2+ single atoms.

Reasonably design of hollow spherical g-C3N4/Mn0.25Cd0.75S heterojunction for efficient photocatalytic hydrogen production and tetracycline degradation

Developing efficient catalysts for photocatalytic hydrogen evolution and pollutant degradation is one of the most ideal methods to address energy and environmental pollution issues. To address the challenges of energy crisis and environmental issues, a hollow spherical g-C3N4/Mn0.25Cd0.75S (HCNS/MCS) heterostructure was constructed and characterized. The unique morphology and appropriate band gap of the hollow carbon nitride sphere (HCNS) make it a promising photocatalytic material. The growth of Mn0.25Cd0.75S solid solution on HCNS enhances the spatial separation of photo-generated charges at the HCNS/MCS interface, thereby promoting electron transfer and reaction kinetics. Under visible light irradiation, the HCNS/MCS exhibited the highest H2 production activity (31.34 mmol·g−1·h−1), which was 2.8 times that of pure MCS and 224 times that of pure HCNS. Moreover, the HCNS/MCS photocatalyst achieved a removal rate of 94% for tetracycline within 180 min under visible light, involving the •OH and •O2- radicals and following the proposed type-Ⅱ mechanism. This work contributes to the design of highly efficient photocatalytic materials with synergistic effects for photocatalytic hydrogen evolution and organic pollutant degradation.

Engineering the axial coordination of cobalt single atom catalysts for efficient photocatalytic hydrogen evolution

Engineering the axial coordination of cobalt single atom catalysts for efficient photocatalytic hydrogen evolution

Construction of heterophase MoOx/Ru assisted by self-assembled carboxymethylcellulose-Ru3+ nanosheet for improved alkaline hydrogen evolution

The hydrogen evolution reaction (HER) in alkaline medium is much sluggish than that in acidic medium due to the limited water dissociation step, thus accelerating the water dissociation kinetics is critical. Herein, we designed a MoOx species-modified ruthenium nanoparticle catalyst (MoOx/Ru/C-3) based on the unique electrostatic interaction between carboxymethylcellulose sodium salt (CMC) and metal ions, where an heterophase structure is formed between MoOx and Ru. The obvious electronic interaction between them allows the formation of synergistic promotion relationship involving the water dissociation on MoOx and the adsorbed hydrogen recombination on Ru. At a metal loading of 6.98 μgRu cm-2 geo, the overpotential of 82 mV is just required to reach a current density of 10 mA cm−2, exhibiting a significantly better apparent electrochemical activity than Ru/C (98 mV) without introduction of MoOx, which demonstrates superior or comparable alkaline HER activity to the recently reported Ru-based electrocatalysts. Meanwhile, the overpotential for Ru/C increased by 113 mV after 24 h of chronopotentiometric test, whereas only 61 mV elevates for MoOx/Ru/C-3, and even just 98 mV generates after 120 h. Thereof, introduction of MoOx species into Ru matrix can also markedly improve the electrochemical stability. The proposed material construction strategy in this study provides a feasible idea for the rational design of highly cost-performance alkaline hydrogen evolution catalysts.

Oxophilic Ce single atoms-triggered active sites reverse for superior alkaline hydrogen evolution

The state-of-the-art alkaline hydrogen evolution catalyst of united ruthenium single atoms and small ruthenium nanoparticles has sparked considerable research interest. However, it remains a serious problem that hydrogen evolution primarily proceeds on the less active ruthenium single atoms instead of the more efficient small ruthenium nanoparticles in the catalyst, hence largely falling short of its full activity potential. Here, we report that by combining highly oxophilic cerium single atoms and fully-exposed ruthenium nanoclusters on a nitrogen functionalized carbon support, the alkaline hydrogen evolution centers are facilely reversed to the more active ruthenium nanoclusters driven by the strong oxophilicity of cerium, which significantly improves the hydrogen evolution activity of the catalyst with its mass activity up to −10.1 A mg−1 at −0.05 V. This finding is expected to shed new light on developing more efficient alkaline hydrogen evolution catalyst by rational regulation of the active centers for hydrogen evolution.

Design of High-Efficiency Hydrogen Evolution Catalysts in a Chiral Crystal

Design of High-Efficiency Hydrogen Evolution Catalysts in a Chiral Crystal

Enhanced photocatalytic hydrogen production from formic acid with reversible electron transfers in PdO/TiO2

A prepared p-type PdO/n-type TiO2 junction was prepared as the catalyst for photocatalytic hydrogen evolution from formic acid (FA). It was found that PdO/TiO2 exhibited 1298-fold higher activity than TiO2 under ultraviolet and visible light irradiation at room temperature. Multiple characterization techniques were utilized to demonstrate that doping PdO into TiO2 can regulate the Fermi level of the sample and the adsorption behavior of FA, resulting in different electron transfer behavior between FA and PdO/TiO2 compared to that between FA and TiO2. Oxygen vacancies acted as electron donors to deliver photogenerated electrons from TiO2 to the adsorbed bidentate FA, which increased the electron density on the O atom of FA and led to the formation of activated monodentate FA. This activated FA was more easily oxidized by the holes in PdO generated by visible light, leading to the production of H2 and CO2. The mode of adsorption associated with the Pd2+ site is the key factor in driving this reaction and leading to the reversible electron transfer phenomenon. This study provides a new promising route for the design of photocatalysts for self-decomposition reactions.

Accelerating Hydrogen Desorption of Nickel Molybdenum Cathode via Copper Modulation for Pure‐Water‐Fed Hydroxide Exchange Membrane Electrolyzer

AbstractThe more sluggish kinetics of hydrogen evolution catalysts in base as compare to that in acid to some degree restricts hydrogen production performance of hydroxide exchange membrane electrolyzers, especially when using earth‐abundant catalysts. Here a ternary nickel–copper–molybdenum hydrogen evolution catalyst is reported that exhibits ≈5 times higher turnover frequency than without copper doping. The X‐ray absorption near‐edge structure and valence band spectrum demonstrate that the light doping of copper into nickel–molybdenum alloy modulates the electronic structure and downshifts the d‐band center, resulting in accelerated hydrogen desorption, as consolidated by H2 temperature programmed desorption and theoretical calculation. An electrolyzer employing this cathode catalyst and a nickel–iron anode, gives a current density of 1.7 A cm−2 at 2.0 V with a pure‐water feed through the anode, which outperforms the 2025 target proposed by the United States Department of Energy, and even is operated continuously for over 1000 h with a decay rate of as low as 0.5 mV h−1. Post‐mortem analysis discloses that hydroxide exchange ionomer migration is one of the key factors affecting long‐term durability. This work demonstrates the feasibility of a low‐cost, water‐fed hydroxide exchange membrane electrolyzer achieving industrial‐level performance and lifetime.

N, P co-doped graphene-supported monometallic nanoparticles for highly efficient hydrogen evolution by acid electrolysis of water

Pt/rGNP exhibits much higher catalytic properties than other transition metal/rGNP catalysts for hydrogen evolution; its overpotential at 100 mA cm−2 in 0.5 M H2SO4 is only 10.6 mV, and its Tafel slope is 14.53 mV dec−1.