Iron-Molybdenum Sulfide Electrocatalysts for the Hydrogen Evolution Reaction: An Operando XAS study

Carbon nanotube supported PtO nanoparticles with hybrid chemical states for efficient hydrogen evolution

Three-dimensional hierarchically porous iridium oxide-nitrogen doped carbon hybrid: An efficient bifunctional catalyst for oxygen evolution and hydrogen evolution reaction in acid

Facile synthesis of interlaced flower-like layered double hydroxides grown on porous CoMoP as a highly efficient electrocatalyst for hydrogen evolution reaction

In recent days, 2-dimensional (2D) niobium disulfide (NbS2) with near-zero Gibbs free energy and superlative acid electrolyte stability has provoked a great deal of interest toward hydrogen evolution reaction (HER) electrocatalyst due to its active basal and edge sulfur sites. Herein, we developed a single step method for the direct deposition of 2D-NbS2 on high-aspect-ratio topographies of silicon nanowires (NWs) by chemical vapor deposition for the applications in HER electrocatalyst. The resultant 2D-NbS2 electrocatalyst demonstrates the HER overpotential of ∼74 mV vs RHE (reversible hydrogen electrode) @ 1 mA/cm2 under acidic conditions and stable for more than 20 h. More importantly, we developed the Si NWs array based photoelectrochemical water-splitting system with the direct deposition of 2D-NbS2 as HER catalyst. The resultant 2D-NbS2-Si NWs photocathode system demonstrates improved charge transfer characteristics at the Si-NbS2 interfaces that leads to an enhanced turn on potential (from 0.06 to 0.34 V vs RHE) with the current density of -28 mA/cm2 at the 0 V vs RHE. The results evidence the synergistic effect of 2D-NbS2 electrocatalysts that addresses poor surface kinetics of Si toward solar water electrolysis. Our comprehensive studies reveal NbS2 as a new class of photoelectrochemical cocatalyst for efficient solar HER performance by promoting the charge transfer process with prolonged acid stability.

Cobalt oxide-based materials as non-PGM catalyst for HER in PEM electrolysis and in situ XAS characterization of its functional state

The development of Pt-free electrocatalysts for hydrogen evolution reaction (HER) is still desired in water-splitting as a clean energy. As a highly efficient HER catalyst, Mo-based catalysts have attracted much attention. Annealing is an indispensable part of the preparation of molybdenum-based HER catalysts, but easy to polymerize during carbonization, resulting in lower HER performance of product. Herein, we report the synthesis of molybdenum carbide N&C-doped (Mo2C@CN) with layered mesoporous structure as HER electrocatalyst. This structure can solve the problem of HER performance due to polymerization. The Mo2C@CN is obtained simply by two steps. Benefiting from the structure and doped of N&C, Mo2C@CN exhibits abundant electrochemically active site and outstanding stability. To attain a current density of 10 mA cm−2 in 0.5 M H2SO4, with overpotentials of 202 mV, Tafel slopes of 69 mV dec−1. Little overpotential decay shows its striking stability (2000 cycles) in the acid media.

MXenes, a novel family of 2D transition metal carbide, nitride and carbonitride materials, have been gaining tremendous interest in recent days as potential electrocatalysts for various electrochemical reactions, including hydrogen evolution reaction (HER). MXenes are characterized by their etchable metal layers, excellent structural stability, versatility for heteroatoms doping, excellent electronic conductivity, unique surface functional groups and admirable surface area, suitable for the role of electrocatalyst/support in electrochemical reactions, such as HER. In this review article, we summarized recent developments in MXene-based electrocatalysts synthesis and HER performance in terms of the theoretical and experimental point of view. We systematically evaluated the superiority of the MXene-based catalysts over traditional Pt/C catalysts in terms of HER kinetics, Tafel slope, overpotential and stability, both in acidic and alkaline electrolytic environments. We also pointed out the motives behind the electro catalytic enhancements, the effect of synthesis conditions, heteroatom doping, the effect of surface terminations on the electrocatalytic active sites of various MXenes families. At the end, various possible approaches were recommended for a deeper understanding of the active sites and catalytic improvement of MXenes catalysts for HER.

Boron-doped CoSe2 nanowires as high-efficient electrocatalyst for hydrogen evolution reaction

Metal/antiperovskite metal nitride composites Ag/AgNNi3 as novel efficient electrocatalysts for hydrogen evolution reaction in alkaline media

Developing new methodologies to produce clean and renewable energy resources is pivotal for carbon‐neutral initiatives. Hydrogen (H2) is considered as an ideal energy resource due to its nontoxic, pollution‐free, high utilization rate, and high calorific combustion value. Electrolysis of water driven by the electricity generated from renewable and clean energy sources (e.g., solar energy, wind energy) to produce hydrogen attracts great efforts for hydrogen production with high purity. Recently, the breakthrough of the catalyst activity limit for the hydrogen evolution reaction (HER) catalysts has received extensive attention. Comparatively, fewer reviews have focused on the long‐term stability of HER catalysts, which is indeed decisive for large‐scale electrolytic industrialization. Therefore, a systematic summary concentrated on the durability of HER electrocatalysts would provide a fundamental understanding of the electrocatalytic performance for practical applications and offer new opportunities for the rational design of the highly performed HER electrocatalysts. This review summarizes the research progress toward the HER stability of precious metals, transition metals, and metal‐free electrocatalysts in the past few years. It discusses the challenges in the stability of HER electrocatalysts and the future perspectives. We anticipate that it would provide a valuable basis for designing robust HER electrocatalysts.image

Low-cast non-noble-based catalysts with high activity and durability are the choices to replace expensive Pt-based catalysts for hydrogen evolution reaction (HER). In this work, polyvinylpyrrolidone (PVP)-modified graphene (PVP-rGO) was synthesized as a composite with a high surface area and additional functional groups for Ni nanoparticle support. Loading of nickel nanoparticles on the PVP-rGO was optimized to obtain an effective non-noble catalyst (Ni/PVP-rGO) for HER in alkaline media. Inductively coupled plasma optical emission spectrometry (ICP-OES) results demonstrated a relatively good accordance between theoretical and experimental metal loading by this facile synthesis procedure. The structure and morphology of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. The activity and stability of the prepared catalysts (with and without PVP) were investigated at HER in alkaline media by different electrochemical techniques. A Tafel slope of 119 mV dec−1 was obtained for Ni/PVP-rGO, which was consistent with the Volmer reaction as the rate determining step (RDS) of HER mechanism. Also, an acceptable durability in HER performance was obtained by Ni/PVP-rGO (working over 62.5 h and 5000 cycles without a notable lost). These results make it as a promising catalyst which could be employed in the cathode side of water electrolyzer in alkaline media.

MXenes, known as the graphene‐like two‐dimensional transition metal carbides, carbonitrides, or nitrides, have been considered as promising electrocatalysts to replace benchmark Pt for hydrogen evolution reaction (HER). Despite the success in fabricating MXenes, their application in catalysis still faces great challenges. One critical drawback is the rapid corrosion and structural evolution of MXenes during storage and HER. In this work, the corrosion and structural evolution of various MXenes in air, aqueous colloidal solutions, and under HER conditions are reviewed. The degradation/structural mechanism of MXenes and effects of structural evolution on the HER activity are in dispute. Preliminary protocols are proposed for future MXene storage and design for HER application. This review provides valuable information to better prevent corrosion of MXenes before and after servicing as HER catalysts, and to interpret the obtained HER performance for MXenes in the view of corrosion/structural evolution.

One promising way to tune the physicochemical properties of materials and optimize their performance in various potential applications is to engineer material structures at the atomic level. As is well known, the performance of Pd-based catalysts has long been constrained by surface contamination and their single structure. Here, we employed an unadulterated top-down synthesis method, known as laser fragmentation in liquid (LFL), to modify pristine PdPS crystals and obtained a kind of metastable palladium-sulfur compound nanoparticles (LFL-PdS NPs) as a highly efficient electrocatalyst for hydrogen evolution reaction (HER). Laser fragmentation of the layered PdPS crystal led to a structural reorganization at the atomic level and resulted in the formation of uniform metastable LFL-PdS NPs. Noteworthy, the LFL-PdS NPs show excellent electrocatalytic HER performance and stability in acidic media, with an overpotential of –66 mV at 10 mA⋅cm−2, the Tafel slope of 42 mV⋅dec−1. The combined catalytic performances of our LFL-PdS NPs are comparable to the Pt/C catalyst for HER. This work provides a top-down synthesis strategy as a promising approach to design highly active metastable metal composite electrocatalysts for sustainable energy applications.

Poor crystalline MoS2 with highly exposed active sites for the improved hydrogen evolution reaction performance

Fabrication of Te@NiTe2/NiS heterostructures for electrocatalytic hydrogen evolution reaction