Electrode For Hydrogen Evolution Research Articles

Nanostructure MoS2 electrocatalyst modified large area carbon electrode for efficient hydrogen evolution

Hydrothermally synthesized nanostructured MoS2 was immobilized over large area graphite paper (5 × 5 mm2) to fabricate electrode for hydrogen evolution application. The chemical optimization via. variation in hydroxylamine hydrochloride(HAH) concentration, led to nanosheets containing surface over the micro-balls, with a 1T and 2H phase of MoS2. A physicochemical and electrochemical characterization yielded a lowest Tafel slope of ∼67 mV dec−1, a lowest over potential of 0.19 V with a significant electrocatalytic stability in acidic. An electrocatalytic hydrogen evolution over optimized MoS2 evolved 2 times (∼46 μmol h−1) of hydrogen gas as compared to that from MoS2 synthesized without HAH. The improved performance of electrocatalyst can be attributed to the combination of phase, and electrochemical properties 2D structure of MoS2.

Interfacial coupling of sea urchin-like (Mo4O11-MoS2-VO2) promoted electron redistributions for significantly boosted hydrogen evolution reaction

Developing efficient electrocatalysts for hydrogen evolution reaction (HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst (Mo4O11-MoS2-VO2) is synthesized by hydrothermal deposition and post-annealing strategy. The optimized electrocatalyst behaves as a high active hydrogen evolution electrode in 0.5 mol/L H2SO4. This electrode needs overpotential of only 43 mV to achieve 10 mA/cm2 with a Tafel slope of 37 mV/dec and maintains its catalytic activity for at least 36 h. Better than most previously reported non-noble metal electrocatalysts anchored on carbon cloth. It is worth mentioning that the hierarchical sea urchin-like structure promotes the redistribution of electrons and provides more catalytic active sites. This strategy shows a way for the construction of inexpensive non-noble metal electrocatalysts in the future.

Ionomer Dispersion for IrO2 Based Oxygen Evolution Reaction Electrode with for Decal Process Application

Green hydrogen production is of importance in the upcoming hydrogen economy era. Proton exchange membrane (PEM) water electrolysis is one of the most important technology to produce the green hydrogen, which requires only water and extra electricity supplied from renewable energy. Main component, i.e., membrane electrode assembly (MEA), is a key part consisting of polymer electrolyte membrane and two electrodes which are oxygen evolution reaction (OER) electrode and hydrogen evolution (HER) electrode. Both electrode should be coated on the surface of membranes for better performance and mass production. HER could be coated by spraying or decal processes since Pt/C electrocatalysts allow to be dispersed in diluted (for spraying) and concentrated (for decal) catalyst inks. However, OER electrode mainly uses IrO2 black electrocatalyst which only allows diluted catalyst inks due to low surface area of IrO2. Thus, OER is generally coated by a spray method. For a decal process for OER electrode, high concentration or high viscosity of catalyst ink should be prepared. In this study, high viscosity ionomer dispersions were prepared using commercially available ionomer dispersions in water and alcohol mixture by substituting water and alcohol solvents into high viscosity solvent (propylene glycol in this study). High viscosity solvent-based ionomer dispersion was investigated for high concentration or high viscosity catalyst ink. The OER electrodes using high viscosity ionomer dispersions were evaluated by electrochemical characterization such as I-V polarization and activation rate. Acknowledgment This research was supported in part by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT ＆ Future Planning (NRF-2019M3E6A1063677) and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.

Mild construction of robust FeS-based electrode for pH-universal hydrogen evolution at industrial current density

The development of fast and mild preparation of transition metal electrocatalysts for efficient and ultra-stable water electrolysis in wide pH range electrolytes is essential for hydrogen energy supply. Herein, ultrathin and metastable FeS nanolayer self-supported on 3D porous iron foam (IF) substrate is fabricated via one-step mild sulfurization etching for only 2 h to obtain FeS@IF electrode, which achieves efficient and long-term hydrogen evolution in alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl), neutral electrolyte (1.0 M PBS) and other corrosive systems. The overpotentials are only 63 mV and 78 mV to drive 10 mA cm−2 during hydrogen evolution in 1.0 M KOH + 0.5 M NaCl and 1.0 M PBS, respectively. Additionally, the FeS@IF electrode continuously catalyzes for over 600 h at 0.2–0.4 A cm−2 in 1.0 M PBS with negligible performance loss, partly attributed to FeS nanolayer firmly etching on the surface and the formation of corrosion-resistant ultrathin nano fan-like iron sulfide oxide (FeOxSy). This uniformly-distributed morphology helps to facilitate the interfacial electron transmission between active species and substrate, expose more active sites, and provide moderate channels for the rapid liberation of gas bubbles and mass transfer. This work proposes a novel strategy for developing efficient and stable catalysts for hydrogen production in wide pH range systems.

Direct Growth of Carbon Nitride (C3N3) Nanosheets on Copper Foam as an Efficient Catalytic Electrode for Electrochemical Hydrogen Evolution

AbstractIn this work, carbon nitride (C3N3) nanosheets are directly synthesized on copper foam via a solvent‐free vapor‐solid phase reaction. Electrochemical measurement results indicate that C3N3 nanosheets achieve outstanding electrocatalytic performances with low overpotential (142 mV@10 mA cm−2) and small Tafel slope (75.5 mV dec−1), which are superior to most metal‐free hydrogen evolution reaction electrocatalysts in acid medium reported so far. In addition, the electrocatalytic performances of C3N3 nanosheets are further slightly improved under simulated solar irradiation. What's more, the synthetic strategy of C3N3 nanosheets could be extended to other substance system. More importantly, our impressive work was expected to inspire more potential researches in the future.

Hyperbranched NixPy/NiCoP Arrays Based on Nickel Foam Electrode for Efficient and Stable Electrocatalytic Hydrogen Evolution

Hyperbranched NixPy/NiCoP Arrays Based on Nickel Foam Electrode for Efficient and Stable Electrocatalytic Hydrogen Evolution

Nanosheet MoS2-Decorated MoO2 on Porous Carbon as Electrodes for Efficient Hydrogen Evolution

To optimize the disadvantage of low conductivity and few active sites of MoS2-based catalysts, in situ growth on carbonized wood (CW) through coupling of conductive materials and MoS2 can be a proven strategy. Herein, a three-dimensional self-supporting electrode with a heterostructure of nanosheet MoS2-decorated MoO2 grown on CW (MoS2-MoO2/CW) is prepared for the hydrogen evolution reaction (HER) via a simple two-step chemical vapor deposition strategy. The coupling of MoS2 and MoO2 with excellent electrical conductivity and the rational design of three-dimensional self-supporting electrodes are the key factors to improve the catalytic performance. The designed MoS2-MoO2/CW electrode has a potential of 148 mV at a current density of 10 mA cm–2, a low Tafel slope of 86.7 mV dec–1, and outstanding long-term stability in 0.5 M H2SO4. Consequently, wood-based porous carbon electrodes with a heterogeneous structure of nanosheet MoS2-decorated MoO2 can provide meaningful references for MoS2-based electrocatalysts.

Electrolytic water technology based on transformable and amorphous liquid metal electrodes

AbstractHydrogen has important values in industrial manufacture, medical health care, and diverse energy application areas. Among the many possible approaches, convenient and safe hydrogen production from water electrolysis has always been a preferred in situ hydrogen supply technology. So far, many of the electrodes thus involved are based on rigid metals or conductive items which may encounter inconvenience or insufficiency sometimes. To achieve targeted release of hydrogen, appropriate administration of suitable flexible hydrogen evolution electrodes is the key. In recent years, gallium‐based liquid metals have emerged in the field of flexible and biological electrodes. Starting from this point, liquid metal is proposed here as a transformable amorphous electrode for hydrogen evolution in electrolytic water which may help mold new conceptual electrolysis and energy utilization ways. The electrochemical performances and flexible behaviors lying behind are investigated and clarified. According to the experiments, the catalytic activity of the liquid metal itself generally is not remarkable, but it would be significantly improved after being composited with certain active materials such as nickel. Further, the controllability, flexibility, and adaptability of liquid metal‐based amorphous materials which are unmatched by other electrode materials were evaluated. Overall, the motions of such shape transformable liquid metal electrodes could be controlled by electric or magnetic fields, and their deformations are compliantly adaptive to different spaces. This might easily expand the area of hydrogen evolution and lead to multisite in situ hydrogen production. The present study demonstrates the value of liquid metals in flexible energy systems and opens up more application possibilities for electrolytic hydrogen production.

High-current water electrolysis performance of metal phosphides grafted on porous 3D N-doped graphene prepared without using phosphine

Development of efficient and stable electrodes for hydrogen and oxygen evolution from water constituted of abundant elements and prepared by sustainable and scalable procedures is of considerable importance for producing green hydrogen from renewable electricity. Herein, a method for the preparation of Ni 2 P, Fe 2 P, and FeP supported on N-doped graphene (NiP/NG and FeP/NG) is reported. The procedure uses metal salts, phosphorous oxide, and chitosan as precursors of metal phosphide and N-doped graphene, avoiding the use of undesirable and hazardous precursors, such as PH 3 or NaH 2 PO 2 , and rendering a material with a strong metal phosphide-graphene interaction. Moreover, NiP/NG and FeP/NG electrodes are demonstrated to be more efficient than the benchmark catalysts Pt/C and RuO 2 , for hydrogen evolution reaction and oxygen evolution reaction, respectively, at a large current density (300 mA/cm 2 ). In addition, water electrolysis was carried out using NiP/NG//FeP/NG electrodes, also demonstrating improved efficiency and stability compared with Pt/C//RuO 2 at a current density (400 mA/cm 2 ) near industrial requirements. • Synthetic procedure for preparing metal phosphides avoiding the use of toxic reagents • The method creates a strong interaction between metal phosphides and the support • Ni 2 P and Fe x P on N-doped graphene electrodes have been prepared for water electrolysis • These can operate at 400 mA/cm 2 for 50 h Transition metal phosphides are promising catalysts for water electrolysis but are commonly prepared using hazardous phosphines. Here Hu et al. prepare electrodes consisting of metal phosphide nanoparticles supported on porous 3D graphene, avoiding the use of hazardous precursors, catalyzing water electrolysis at high current density near industrial requirements.

Promotion of Phenol Electro-oxidation by Oxygen Evolution Reaction on an Active Electrode for Efficient Pollution Control and Hydrogen Evolution.

We report an electrolysis system using NiFe layered double hydroxide/CoMoO4/nickel foam (NFLDH/CMO/NF) as the anode and CMO/NF as the cathode for simultaneous phenol electro-oxidation and water electrolysis. This system shows high performance for both phenol degradation and hydrogen evolution. We demonstrate that the degradation rate of phenol on the active anode is governed by the mass transfer rate at a low phenol concentration (0.5-2 mM) and by the electro-oxidation rate at a high phenol concentration (5 mM). The anodic oxygen evolution reaction (OER) can promote the phenol degradation through enhanced mass transfer efficiency. More importantly, the common deactivation issue of phenol electro-oxidation on the inert anode can be eliminated by the high OER activity of the active anode. The constructed full electrolytic cell only needs a low potential of 1.498 V to achieve 10 mA/cm2 for water electrolysis. The reported promotion effect of phenol degradation by OER as well as the improved anode resistance to deactivation offer new insights into efficient and robust waste-to-resource electrolysis system for water treatment.

Electrodeposition of NiCu bimetal on 3D printed electrodes for hydrogen evolution reactions in alkaline media

In this study, hydrogen evolution electrodes are prepared by a 3D printing method using conductive PLA filament. To improve their conductivity and electrochemical performance, Nickel–Copper (NiCu) binary coating is deposited on 3D printed (3DP) electrodes in a solution bath with different volume ratios. Electrodes have been prepared as NixCux, NixCu2x, and NixCu3x according to Ni and Cu volume ratio (Ni–Cu; 10-10, 10–20, and 10–30 mL, respectively). Surface morphologies of the samples are measured using FE-SEM, EDX and XRD techniques. Electrochemical characterizations are investigated by LSV, CV and EIS. According to the results, the current density of NiCu coated 3DP electrodes is higher than the uncoated 3DP electrode. The results show that the resistance values of the electrodes are decreased from 0.262 kΩ to 0.187 kΩ in NixCu3x electrode. • Electrodes were prepared by 3D printing method using conductive PLA filament. • Different volume ratios of Ni and Cu metals were deposited on the 3DP electrode. • HER activities of 3DP electrodes were investigated in the alkaline medium at 25 °C. • The kinetic performance of NiCu coated 3DP electrodes was improved significantly. • NixCu3x coated 3DP electrode was provided a good kinetic activity for HER.

Mo2C@C nanofibers film as durable self-supported electrode for efficient electrocatalytic hydrogen evolution

Self-supported electrocatalytic thin films consist 3D conducting network and well-embedded electrocatalysts, which endows the advantage in mass flow kinetics and durability for large-scale water splitting. Synthesis of such self-supported electrode still remains a big challenge due to the difficulty in the control over the 3D conducting network and the simultaneous growth of catalyst with well attachment on the conducting fibers. Herein, a self-supported Mo2C@carbon nanofibers (Mo2C@C NF) film has been successfully fabricated with outstanding electrocatalytic performance under optimized pyrolysis temperature and precursors mass ratio conditions. During the carbonation process, the Mo2C nanoparticles (∼16 nm) were simultaneously grown and well dispersed on the inter-connected carbon nanofibers, which formed a 3D conducting network. The as-formed 3D carbon network was strong enough to support direct electrocatalytic application without additional ink or supporting substrates. This particular electrode structure facilitated easy access to the active catalytic sites, electron transfer, and hydrogen diffusion, resulting in the high hydrogen evolution reaction activity. A low overpotential of 86 mV was needed to achieve 10 mA cm−2 current density with outstanding kinetics metric (Tafel 43 mV dec−1) in 1 M KOH. Additionally, the self-supported Mo2C@C NF film, a binder-free electrode, exhibited extraordinary stability of more than 340 h.

Defect-rich engineering of Ni-incorporated tungsten oxides micro-flowers on carbon cloth: A binder-free electrode for highly efficient hydrogen evolution reaction

Hydrogen generated by electrocatalysis water splitting is a promising way to harvest clean energy. However, exploring the cheap and highly efficient electrocatalysts with Pt-like activity for hydrogen evolution reaction (HER) remains great challenges. Herein, we report hierarchical Ni-incorporated oxygen vacancies-rich tungsten oxides micro-flowers on 3D conductive carbon cloth support (denoted as Ni–W H2-550) as a binder-free electrode for high efficient hydrogen evolution. The binder-free 3D structure and the synergistic effect between Ni-incorporated and rich oxygen vacancies can regulate the electronic structure, facilitate the electron transfer, and enlarge the exposed active sites. The as-prepared Ni–W H2-550 exhibits a low overpotential of 25 mV at 10 mA cm−2 with robust stability in alkaline electrolyte solution over 20 h. This study opens up a concise strategy toward the preparation of the low-cost and highly efficient electrocatalyst for HER.

Sintered Ni metal as a matrix of robust self-supporting electrode for ultra-stable hydrogen evolution

For the self-supporting catalysts of Hydrogen evolution reaction (HER), the rational design and fabrication of substrate with porous structure and sufficient mechanical strength are critical to promoting the industrial HER application. In this work, a novel porous sintered Ni metal as the matrix for supporting catalysts was successfully prepared by powder metallurgy, and a self-supporting electrode for HER was fabricated via a simple sulfurization process on this sintered Ni metal matrix. For instance, MoS2/Ni3S2 nanorods (NRs) were vertically grown on the as-sintered porous Ni matrix, and the morphology of the sintered Ni matrix significantly affected the growth of MoS2/Ni3S2 NRs. The [email protected] Ni electrode shows a low overpotential of η10 = 56 mV and Tafel slope of 82 mV dec−1. Compared with [email protected] foam, the [email protected] Ni exhibits superior stability, where no exfoliation and cracks are observed on the surface of the electrode after 5000 CV cycles. Ultra-high stability and long-term durability are obtained over 100 h even at high potentials of 200 and 300 mV. Moreover, the tensile strength of the as-obtained electrode based on the sintered Ni manifests nearly 260 times higher than that of [email protected] foam, evidencing an excellent mechanical property. This work provides an idea for the preparation of self-supporting metal-based catalytic electrodes in large-scale hydrogen production.

C-O-Co bond-stabilized CoP on carbon cloth toward hydrogen evolution reaction

Highly active, low-cost, and durable electrocatalysts toward hydrogen evolution reaction (HER) are crucial for electrochemical water splitting. Herein, a green, facial, and effective strategy was proposed to develop CoP on carbon cloth (CoP/o-CC) as efficient self-supported hydrogen evolution electrodes. The designed CoP/o-CC exhibits superior catalytic activity with overpotentials of 118 mV and 95.45 mV to deliver a current density of 10 mA cm −2 in acidic and alkaline solution, respectively, which is superior to most reported studies. In addition, the designed CoP/o-CC electrode also possesses excellent stability even under a large current density of 100 mA cm −2 . The origin of significantly enhanced stability thereby was further systematically investigated. Experimental study reveals that the oxygenated functional groups on carbon cloth play the role to bind the CoP electrocatalysts, forming C-O-Co bonds. Thus, the enhanced electrochemical and structural stability of CoP/o-CC is predominantly caused by the interfacial interaction of the C-O-Co bonds between the CoP active materials and surface oxygenated functional groups of carbon fiber. Therefore, we believe that this work provides an in-depth insight into the role of interfacial interaction between the substrate and the catalysts and offers a new methodology to design durable and efficient electrocatalysts. • The high-performance CoP on carbon cloth (CoP/o-CC) was fabricated. • A green and facial strategy was developed to prepare CoP/o-CC. • The significantly enhanced stability of the designed CoP/o-CC was illustrated. • The oxygenated functional groups on carbon fiber will bind to the CoP catalyst.

Modulation of Water Dissociation Kinetics with a "Breathable" Wooden Electrode for Efficient Hydrogen Evolution.

Innovative breakthroughs regarding self-supported open and porous electrodes that can promote gas-liquid transmission and regulate the water dissociation kinetics are critical for sustainable hydrogen economy. Herein, a free-standing porous electrode with Pd-NiS nanoparticles assembled in a multichannel carbonized wood framework (Pd-NiS/CW) was ingeniously constructed. Specifically, carbonized wood (CW) with a mass of open microchannels and high electrical conductivity can significantly facilitate electrolyte permeation ("inhalation"), hydrogen evolution ("exhalation"), and electron transfer. As expected, the fabricated "breathable" wooden electrode exhibits remarkable hydrogen evolution activity in 1.0 M KOH, only requiring a low overpotential of 80 mV to sustain a current density of 10 mA cm-2, and can maintain this current density for 100 h. Further, the spectroscopic characterization and density functional theory (DFT) calculations manifest that the electron interaction between Pd and NiS is beneficial to reduce the water dissociation energy barriers, optimize the adsorption/desorption of H, and ultimately accelerate the catalytic activity. The work reported here will provide a potential approach for the design of electrocatalysts combined with natural multichannel wood to achieve the goal of high electrocatalytic activity and superior durability for hydrogen production.

Three-dimensional crystalline-Ni5P4@amorphous-NiOx core–shell nanosheets as bifunctional electrode for urea electro-oxidation and hydrogen evolution

The electrochemical urea oxidation (UOR) involves the generation of gases bubbles, which often cause the blockage of the electrode surface leading to decline activity. Herein, we report the growth of Ni5P4 nanosheets on nickel foam as bifunctional electrode (CA-Ni5P4@NiOx/NF) for urea electrolysis. The results indicated that a thin layer of amorphous NiOx formed on the surface of Ni5P4 nanosheets to yield a unique crystalline@amorphous core–shell structure, which can be maintained during long time urea electrolysis. The outstanding UOR performance of CA-Ni5P4@NiOx/NF was attributed to the unique structure, which not only combine the good conductivity and abundant active sites, but also rendered the CA-Ni5P4@NiOx/NF superhydrophilic and aerophobic that significantly facilities the release of gases bubbles formed during UOR to avoid the blockage of the active sites. As a result, the CA-Ni5P4@NiOx/NF electrode exhibited excellent performance for UOR, which only needs 1.45 V (vs. RHE) to deliver a current of 100 mA/cm2. When used as anode for direct urea fuel cell (DUFC), it could reach a maximal power density as high as 3.4 mW/cm2with an OCV of 0.76 V. The CA-Ni5P4@NiOx/NF also exhibited excellent activity for hydrogen evolution reaction (HER), with -0.089 V (vs. RHE) to deliver a current of 10 mA/cm2. The electrolyzer constructed with CA-Ni5P4@NiOx as both anode and cathode could run for more than 10 h at a high current load about 100 mA/cm2 without appreciable potential change, indicating the superb stability of the CA-Ni5P4@NiOx electrode. Our work provides new insights for understanding as well as the development of advanced electrode for DUFC and urea electrolysis.

Electroless Deposition of Ni-W-P Films as Binder-Free, Efficient and Durable Electrode for Electrochemical Hydrogen Evolution

Electroless Deposition of Ni-W-P Films as Binder-Free, Efficient and Durable Electrode for Electrochemical Hydrogen Evolution

Laser Direct Writing of a Strongly Coupled Ag(S)@Nio/Nickel Foam Electrode for Hydrogen Evolution at Ultrahigh Current Densities with Long-Term Durability

Laser Direct Writing of a Strongly Coupled Ag(S)@Nio/Nickel Foam Electrode for Hydrogen Evolution at Ultrahigh Current Densities with Long-Term Durability

Ultrasonically derived WSe2 nanostructure embedded MXene hybrid composites for supercapacitors and hydrogen evolution reactions

Two-dimensional (2D) transition metal chalcogenides (TMDCs) and carbide have validated boundless prospective as multi-functional constituents for high performance energy storing and/or conversion devices. However, pure TMDCs exhibit poor performance for electrochemical applications due to low electrical conductivity, scarce electrochemically active edges and inadequate cycling stability. Therefore, this paper fabricated MXene/WSe2 hybrids with strong interfacial interactions and conductivities using a one-step chemical reaction as electrodes for supercapacitors and hydrogen evolution. Fabricated supercapacitors achieved high specific capacitance = 840 F g−1 at 2 A g−1, with symmetric capacitance = 246 F g−1 at 2 A g−1 for MXene/WSe2 hybrids. Hydrogen evolution achieved low overpotentials = 76 and 62 mV to drive 10 mA cm−2 current with small Tafel slopes = 78 and 84 mV.dec−1 in acid and base media, respectively. 2D and 2D hybrid WSe2 nanoparticle composite embedded MXene scaffolds achieved excellent electron/ion intercalation owing to its distinctive 2D-layered structure, increasing interlayer spacing and retaining large electrode/electrolyte contact to enhance efficiency. Two-dimensional TMDCs/MXene composites were verified as potentially efficient electrode materials for energy storing and exchange uses.