Durability For Hydrogen Evolution Reaction Research Articles

Independent Control Over the H/OH Adsorption: Breaking the Trade-Off Between H/OH-Adsorption and H2O-Dissociation of Platinum-Group Metal Electrocatalyst for Hydrogen Evolution Reaction.

Platinum-group metals catalysts (such as Rh, Pd, Ir, Pt) have been the most efficient hydrogen evolution reaction (HER) electrocatalysts due to their moderate H adsorption strength, while the high H2O-dissociation barrier in alkaline media restrains the catalytic performance of PGM catalysts. However, the optimization of the H2O-dissociation barrier and *H/*OH binding energy toward their individual optima is limited due to the constraints of their scaling relationship on a single active site. Here, a coordinatively unsaturated "M─Ox─W" (M = Rh, Pd, Ir, Pt) active area is constructed, where H and OH species are anchored on Pt-group metal sites and inactive W sites for individual regulation. By combining experiments and density functional theory calculations, the introduction of extra OH-adsorption sites (coordinatively unsaturated WO3-x) avoids the competitive adsorption of H and OH on the single site, while the enhanced OH-adsorption capacity on the coordinatively unsaturated WO3-x effectively facilitates the adsorption/dissociation of interfacial H2O. As a result, the representative Rh-WO3-x catalyst exhibits outstanding catalytic activity and durability for HER. The findings of this work not only provide valuable insights for the design of efficient PGM catalysts for HER but also shed light on the development of electrocatalysts for other catalytic reactions.

Universal and large-scale transform engineering from commercial metals to micron/nanoporous metals via an induced oxidation-reduction reaction

Three-dimensional (3D) nanoporous metals are being increasingly utilized in various fields such as catalysis, energy storage, and sensing. However, the conventional fabrication approaches for 3D nanoporous metals, such as dealloying and template methods, require additional sacrificial materials and multiple fabrication steps and generate chemical waste. Herein, we propose a novel gaseous (O2 and H2) oxidation-reduction (GOR) method to directly transform various transition metals/alloys into 3D micron/nanoporous materials by utilizing the spontaneous reconstruction of metallic atoms. This method eliminates the need for sacrificial materials and acidic/alkaline solutions, making it facile, cost-effective, and environmentally friendly. The resulting micron/nanoporous Ni/Ni alloy exhibits excellent mechanical properties, atomic hydrogen adsorption capability, and hydrophilicity, leading to outstanding electrocatalytic activity and durability for hydrogen evolution reaction.

Carbon Nanotube Support, Carbon Loricae and Oxygen Defect Co-Promoted Superior Activities and Excellent Durability of RuO2 Nanoparticles Towards the pH-Universal H2 Evolution.

This work reports a strategy that integrates the carbon nanotube (CNT) supporting, ultrathin carbon coating and oxygen defect generation to fabricate the RuO2 based catalysts toward the pH-universal hydrogen evolution reaction (HER) with high efficiencies. Specifically, the CNT supported RuO2 nanoparticles with ultrathin carbon loricae and rich oxygen vacancies at the surface (C@OV-RuO2/CNTs-325) have been synthesized. The C@OV-RuO2/CNTs-325 shows superior activities and excellent durability for the HER. It only requires overpotentials of 36.1, 18.0, and 19.3mV to deliver -10mA cm-2 in the acidic, neutral, and alkaline media, respectively. Its HER activities are comparable to that of the Pt/C in the acidic media but higher than those of the Pt/C in the neutral and alkaline media. The C@OV-RuO2/CNTs-325 shows excellent HER durability with no activity losses for > 500h in the acidic, neutral or alkaline media at -250mA cm-2. The density-functional-theory calculations indicate that the CNT supporting, the carbon coating, and the OVs can modulate the d-band centers of Ru, increasing the HER activities of C@OV-RuO2/CNTs-325, and stabilize the Ru atoms in the catalyst, increasing the durability of the C@OV-RuO2/CNTs-325. More interestingly, the C@OV-RuO2/CNTs-325 shows great potential for practical applications toward overall seawater splitting.

Atomically dispersed Au single sites and nanoengineered structural defects enable a high electrocatalytic activity and durability for hydrogen evolution reaction and overall urea electrolysis

The development of exceptionally active and stable trifunctional electrocatalysts is essential to facilitate industrial applications of proton exchange membrane electrolyzers. Rare earth catalysts have a wide range of applications in alkaline solution oxidation, but limitations in their stability and activity prevent their further application. In this paper, Au doped CeO2 coated porous Aux/CeO2 (x = 1,2,3) was designed as a three-function electrocatalyst with excellent performance and stability. At 1 M KOH conditions, both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) reactions exhibit excess potentials of 159.6 and 320.8 mV at a current density of 10 mA cm-2. In addition, when incorporated into an Au2/CeO2 (0.05 mmol, HAuCl4·4H2O) microparticles, the catalyst exhibits the potential of 1.42 V(10 mA cm-2) containing 0.33 M urea in 1 M KOH. Remarkably, for hydrogen production driven by urea electrolysis, Au2/CeO2 demonstrated exceptional performance by requiring only a voltage input of 1.63 V. The reducing agent that forms the Au/CeO2 heterojunction modulates the electronic structure of the Au active site and optimizes the adsorption of the intermediate. In addition, the interaction of the Au monolayer with the CeO2 nanosphere effectively prevents excessive oxidation and dissolution of Au, and the porous hollow structure provides additional exposed active sites and facilitates mass transfer.

N-doped Ru/Mo2C-based electrocatalyst for outstanding and durable hydrogen evolution reaction with universal pH

The fabrication of Pt-free electrocatalysts with outstanding activity is crucial for reducing the overpotential of the hydrogen evolution reaction (HER) and advancing the next generation of energy technologies. This study introduced a scalable one-pot pyrolysis approach for fabricating N-doped Ru/Mo2C (MCNRx) for HER. The MCNR1 catalyst offered several advantages for electrocatalytic applications and beyond. The N-doped Ru/Mo2C prevented the agglomeration of Mo2C nanomaterials and improved their electronic conductivity. Moreover, the Ru metal was uniformly distributed, providing a large number of active catalytic sites, and the enhanced crystallinity and conductive surfaces generated from the trimesic acid create mass electron migration and facilitate the presence of active centers. The MCNR1 electrocatalyst, designed with the abovementioned advantages, had exceptional performance for HER across a broad pH range. For instance, it achieved a current density of 10 mA cm−2 with an overpotential of 35 mV in 1.0 M KOH, 44 mV in 0.5 M H2SO4, and 196 mV in 1.0 M phosphate-buffered saline (PBS). Furthermore, the electrocatalyst had exceptional long-term stability across all pH levels compared to Pt/C. The synthetic approach devised in this study can be employed for various cost-effective replacements for Pt-based electrocatalysts for HER.

Effects of Intrinsic Defects in Pt-Based Carbon Supports on Alkaline Hydrogen Evolution Reaction.

Carbon material has widely been utilized in the synthesis of efficient carbon-supported Pt (Pt/C) catalysts, in which the structural properties greatly influence the electrocatalytic performances of Pt/C catalysts. However, the effects of intrinsic defects in carbon supports on the performance of the alkaline hydrogen evolution reaction (HER) have not been systematically investigated. Herein, porous carbon supports with different degrees of intrinsic defects were prepared by a simple template-assisted strategy, and the resulting samples were systematically studied by various analytical methods. The results suggested that the presence of abundant intrinsic defects (vacancy and topological defects) in the carbon support was advantageous in terms of favoring the dispersion and anchoring of Pt species, promoting electron transfer between Pt atoms and the carbon support, and tuning the electronic states of Pt species. These features improved the HER performance of Pt/C catalysts. Compared to the nontemplate-assisted carbon-supported Pt catalyst (Pt/NTC) with an overpotential of 178 mV, the optimized template-assisted carbon-supported Pt catalyst (Pt/TC) exhibited a lower overpotential of 58 mV at 10 mA cm-2. Besides, the Pt/TC catalyst displayed better HER durability than the Pt/NTC catalyst owing to its strong metal-support interaction. The DFT calculations confirmed the important role played by intrinsic defects (vacancy and topological defects) in stabilizing Pt atoms, with Pt-C3 coordination identified as the most favorable structure for improving the HER performance of Pt. Overall, novel insights on the significant contribution of intrinsic defects in porous carbon supports on the HER performances of Pt/C catalysts were provided, useful for future design and fabrication of advanced carbon-supported catalysts or other carbon-based electrode materials.

Efficient optimization of electron transfer pathway by constructing phosphide/ceria interface boosts seawater hydrogen production

Developing efficient and durable hydrogen evolution reaction (HER) electrocatalysts is one of the most important issues for the commercialization of seawater electrolysis, but it remains challenging. Here, we report a CeO2-CoP nanoneedle array catalyst loaded on Ti mesh (CeO2-CoP/TM) with work-function-induced directional charge transport properties. The CeO2-CoP/TM catalyst showed superior HER catalytic activity and stability, with overpotentials of 41 and 60 mV to attain 10 mA cm−2, in 1 M KOH and 1 M KOH + seawater electrolyte, respectively. Experimental results and theoretical calculations reveal that the work function drives the charge transfer from CeO2 to CoP, which effectively balances the electronic density of CoP and CeO2, optimizes the d-band center, and accelerates the water activation kinetics, thus enhancing the HER activity. The solar-driven water electrolysis device displays a high and stable solar-to-hydrogen conversion efficiency of 19.6%. This study offers a work function-induced directional charge transport strategy to design efficient and durable catalysts for hydrogen production.

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.

Ultrafine Ru nanoparticles stabilized by V8C7/C for enhanced hydrogen evolution reaction at all pH

The development of cost-effective electrocatalysts with high efficiency and long durability for hydrogen evolution reaction (HER) remains a great challenge in the field of water splitting. Herein, we design an ultrafine and highly dispersed Ru nanoparticles stabilized on porous V8C7/C matrix via pyrolysis of the metal–organic frameworks V-BDC (BDC: 1,4-benzenedicarboxylate). The obtained Ru-V8C7/C composite exhibits excellent HER performance in all pH ranges. At the overpotential of 40 mV, its mass activity is about 1.9, 4.1 and 9.4 times higher than that of commercial Pt/C in acidic, neutral and alkaline media, respectively. Meanwhile, Ru-V8C7/C shows the remarkably high stability in all pH ranges which, in particular, can maintain the current density of 10 mA cm−2 for over 150 h in 1.0 mol L−1 phosphate buffer saline (PBS). This outstanding HER performance can be attributed to the high intrinsic activity of Ru species and their strong interface interactions to the V8C7/C substrate. The synergistic effect of abundant active sites on the surface and the formed Ru–C–V units at the interface promotes the adsorption of reaction intermediates and the release of active sites, contributing the fast HER kinetics. This work provides a reference for developing versatile and robust HER catalysts by surface and interface regulation for pH tolerance.

Carbon-supported Au25 cluster catalysts partially decorated with dendron thiolates: enhanced loading weight and durability for hydrogen evolution reaction.

In order to establish a design principle for efficient Au electrocatalysis, it is desirable to synthesize a highly loaded, robust, and atomically precise Au cluster catalyst on a conductive carbon support. In this work, heterogeneous Au25 catalysts were prepared by calcining 5.0 wt% of mixed ligated [Au25(D2S)x(PET)18-x]0 (D2S = second generation Fréchet-type dendron thiolate, PET = 2-phenylethanethiolate) on a carbon support. X-ray absorption fine structure analysis, powder X-ray diffraction, and aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) revealed the successful synthesis of carbon-supported partially thiolated Au25 clusters by calcining [Au25(D2S)10.7(PET)7.3]0 at 425 °C for ≥12 h, whereas calcination of [Au25(PET)18]0 under the same conditions resulted in thermally induced aggregation into larger Au nanoparticles. The D2S-modified Au25 catalyst showed better durability than PET-modified Au25 in electrocatalytic hydrogen evolution reaction. The higher durability was attributed to the suppression of aggregation of Au25 clusters during the reaction, as confirmed by AC-HAADF-STEM. These results indicate that the residual D2S ligands on Au25 enhance the stability against aggregation more than the residual PET due to stronger non-covalent interactions with carbon supports and/or greater steric hindrance of dendritic structure. This work demonstrates that the stability of Au catalysts can be improved by partial decoration with designed ligands.

Integrated PtxCoy-Hierarchical Carbon Matrix Electrocatalyst for Efficient Hydrogen Evolution Reaction.

Pt-based catalysts are regarded as state-of-the-art electrocatalysts for producing clean hydrogen energy; however, their wide application is restricted by their low abundance, high cost, and poor stability. Herein, we report an integrated PtxCoy-hierarchical carbon matrix electrocatalyst (Pt/Co@NCNTs, Pt3Co@NCNTs, PtCo@NCNTs, and PtCo3@NCNTs) that is developed using a thermally driven Co migration strategy forming alloy nanoparticles to achieve efficient hydrogen evolution reaction (HER). Benefiting from its electronic regulation effect and unique hierarchical hollow structure, the Pt3Co@NCNTs catalyst loaded with 11.5 wt % Pt exhibits superior catalytic performance and durability for HER compared with commercial 20 wt % Pt/C. Under both alkaline and acidic conditions, Pt3Co@NCNTs exhibits excellent HER activity with overpotentials of 21 and 45 mV at 10 mA cm-2, respectively. Density functional theory (DFT) results further verify that the interaction between Pt and Co in Pt3Co@NCNTs can modulate electronic rearrangement, optimize the d-band center, and accelerate water dissociation and *H desorption, thereby enhancing HER activity.

Crystalline-amorphous M@MNx (M = Co, Fe, Ni) encapsulated in nitrogen-doped carbon for enhanced efficient and durable hydrogen evolution reaction

Crystalline-amorphous M@MNx (M = Co, Fe, Ni) encapsulated in nitrogen-doped carbon for enhanced efficient and durable hydrogen evolution reaction

Electrosynthesis and Performance of Homogeneously Mesoporous Ni-Rich Ni-Pt Thin Films for Efficient Hydrogen Evolution Reaction in Acidic Media

The development of green hydrogen technology requires abundant electrocatalyst materials to (partially) replace costly platinum while maintaining the catalytic efficiency and durability. Nickel is an excellent choice for the partial replacement of Pt for water splitting, and is widely used for electrocatalysis in alkaline media. Although Ni cannot provide an activity identical to Pt, specific nanostructures aimed at a high surface-to-volume ratio, such as nanoporous structures, can significantly improve catalytic efficiency. However, in acidic media, the use of non-noble metals for electrocatalysis requires extensive durability tests to confirm the stability of the alloy. Additionally, the impact of hydrogen itself is often overlooked, as hydrogen is known to cause hydrogen embrittlement in Ni and its alloys.This contribution deals with the synthesis of a homogeneously mesoporous Ni-Pt alloy with high catalytic efficiency (Fig. 1). By electrodeposition from aqueous media, Ni-rich Ni-Pt alloy thin films are synthesised in a wide compositional range (between 60 and 99 at% Ni), depending on the deposition potential. The addition of the amphiphilic block copolymer Pluronic P-123 to the electrolyte formulation enables a micelle-assisted deposition process, resulting in films with homogeneous porosity with an approximate pore size of 10 nm irrespective of composition. Moreover, all thin films are single-phase and nanocrystalline [1], and show excellent performance under hydrogen evolution reaction (HER) in acidic media [2].As determined by Rutherford backscattering (RBS), the as-deposited Ni-Pt thin films with film thickness between 180 nm and 260 nm exhibit Pt enrichment at the surface of 1-2 nm in depth, after which Ni and Pt exhibit constant composition over depth. After hydrogen evolution in 0.5 M H2SO4, a gradient in Ni/Pt ratio over the film thickness is established, indicating preferential leaching of Ni into the electrolyte, and resulting in higher Pt content at the surface. Due to the porosity of the thin films, this leaching affects the entire film thickness. A chronopotentiometric durability test (24 h) reveals that the overpotential stabilises over time, indicating that the leaching of Ni is suppressed once a certain Pt/Ni ratio is attained in the thin films. In addition, the HER electrocatalysis is accompanied by a significant hydrogen uptake, determined by elastic recoil detection analysis (ERDA). Depending on the electrodeposition parameters, the as-deposited thin films already exhibit significant hydrogen concentrations between 2 and 10 at%. After the HER durability test, local cracking is observed by SEM, related to an excess of hydrogen in the thin films. Despite the cracking, no significant detachment of the films from the substrate is observed. The hydrogen contained in the films is assumed to be interstitial and does not affect the metallic nature of the Ni-Pt films. An X-ray photoelectron spectroscopy (XPS) post-analysis shows that the fraction of metallic Ni with respect to Ni in higher oxidation states is higher after exposure to the HER than for the as-prepared surface. Acknowledgement: Financed by the European Union – NextGenerationEU.[1] K. Eiler, J. Fornell, C. Navarro-Senent, E. Pellicer, J. Sort, Nanoscale, 2020, 12, 7749[2] K. Eiler, S. Suriñach, J. Sort, E. Pellicer, Appl. Catal. B, 2020, 265, 118597Figure 1: SEM micrograph of a mesoporous Ni93Pt7 thin film. Figure 1

Efficient fabrication of Ni-S/MoS2 hybrid nanoflowers for improved hydrogen evolution in acid media

It is significant to develop highly efficient and cost-effective hydrogen evolution reaction (HER) electrocatalysts. Herein, we propose an efficient fabrication of Ni-S/MoS2 hybrid nanoflowers grown on Ti foil (Ni-S/MoS2/Ti) via a simple one-step hydrothermal reaction method. When used as a HER catalyst, Ni-S/MoS2/Ti exhibits superior HER performances compared with MoS2 grown on Ti foil (MoS2/Ti) and Ni-S adsorbed on Ti foil (Ni-S/Ti) counterparts in acid media, due to its increased active surface area, enhanced electrical conductivity and synergistic effects from the coexistence of bimetallic sulfides. Additionally, Ni-S/MoS2/Ti demonstrates good HER durability, resisting the acid corrosion during HER process.

Siderophore mediated in vitro synthesis of electrocatalytic nanocrystallite struvite variants for highly efficient and durable hydrogen evolution reaction

We report in vitro nanocrystallite variants of Ni and Co struvite formed by bacterial siderophore using the green synthesis method. Assembling of siderophore mediated nanocrystallite struvite variants in the presence of Mg2+, Ni2+ and/or Co2+ and PO43− ions (pH- 9.0) has been investigated. The nanocrystallite struvite was characterized by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy, Raman spectroscopy for their structural, and X-ray powder diffraction for its crystal structure in conjunction with density functional theory. A strategy described here can be explored for rapid synthesis and a large-scale production of modified struvite nanocrystallite materials. Moreover, the potential implications of siderophore accompanying the struvite variant formation facilitated by sequestering electroactive metal ions are discussed. More importantly, the Ni struvite variant demonstrated high electrochemical hydrogen evolution reaction (HER) with overpotential of −59 mV at 10 mA/cm2 current density which is at par with the benchmark Pt electrocatalysts. The stability of Ni struvite during the HER at overpotential and at 100 mA/cm2 applied current density has been demonstrated.

Improving the electrocatalytic hydrogen evolution reaction through a magnetic field and hydrogen peroxide production co-assisted Ni/Fe3O4@poly(3,4-ethylene-dioxythiophene)/Ni electrode

The production of high-purity hydrogen using surplus electrical energy and abundant water resources has immense potential in mitigating the fossil energy crisis, as hydrogen fuel holds clean, pollution-free, and high-energy characteristics. However, the practical application of large-scale hydrogen production from water faces challenges such as high overpotentials, sluggish dynamics, and limited electrocatalytic lifetime associated with the hydrogen evolution reaction (HER). Here, we fabricated the sandwich structure of a Ni/Fe3O4@poly(3,4-ethylene-dioxythiophene)/Ni (Ni/Fe3O4@PEDOT/Ni) electrode and employed a strong magnet to obtain a magnetic electrode capable of achieving high-activity and durability for HER. Electrochemical analysis reveals that the activated magnetic electrode displays a significantly reduced overpotential and an extended electrocatalytic lifetime of 10 days. Notably, its stability is higher than that of non-magnetic Ni/Fe3O4/Ni and Ni/Fe3O4@PEDOT/Ni electrodes, primarily due to the support from magnetic force and the protective PEDOT layer. Moreover, the minute atomized droplets can form the H2O2 species in a moist environment, facilitating the formation of the NiO layer on the Ni surface, which plays a vital role in boosting catalytic activity. In conclusion, our magnetic electrode strategy, combined with the emergence of the NiO layer, offers valuable insights for the development of advanced HER electrodes.

CDs Regulated Sulfur-Based Flexible Electrode with Range pH Values for Efficient and Durable Hydrogen Evolution Reaction.

How to mildly structure a high intrinsic activity and stable catalytic electrode to realize long-term catalytic water splitting to produce hydrogen at a wide range of pH values at industrial high current is a challenge. Herein, this work creatively proposes to prepare industrial-grade catalytic electrodes with high efficiency and stability at high current density through carbon quantum dots (CDs) modification nickel sulfide on hydrophilic flexible filter paper via one-step mild chemical plating (denoted as CDs-Ni3 S2 @HFP). The intrinsic activity and surface area, electron transfer ability, and corrosion resistance of Ni3 S2 material are increased due to the regulation, homogenous, and high concentration doping of CDs. The overpotential of the flexible catalytic electrode is only 30, 35, and 87mV in 1m KOH, simulated seawater (1m KOH + 0.5m NaCl), and neutral electrolyte (0.5m PBS) at a current density of 10mA cm-2 . More attractively, the CDs-Ni3 S2 @HFP electrode achieves over 500h of efficient and stable catalysis at industrial high current density (500mA cm-2 ). Due to the advantages of mild, universal, and large-area preparation of catalytic materials, this work provides technical support for flexible catalytic electrodes in efficient catalysis toward water splitting, energy storage, and device preparation.

Escalating Catalytic Activity for Hydrogen Evolution Reaction on MoSe2@Graphene Functionalization.

Developing highly efficient and durable hydrogen evolution reaction (HER) electrocatalysts is crucial for addressing the energy and environmental challenges. Among the 2D-layered chalcogenides, MoSe2 possesses superior features for HER catalysis. The van der Waals attractions and high surface energy, however, stack the MoSe2 layers, resulting in a loss of edge active catalytic sites. In addition, MoSe2 suffers from low intrinsic conductivity and weak electrical contact with active sites. To overcome the issues, this work presents a novel approach, wherein the in situ incorporated diethylene glycol solvent into the interlayers of MoSe2 during synthesis when treated thermally in an inert atmosphere at 600 °C transformed into graphene (Gr). This widened the interlayer spacing of MoSe2, thereby exposing more HER active edge sites with high conductivity offered by the incorporated Gr. The resulting MoSe2-Gr composite exhibited a significantly enhanced HER catalytic activity compared to the pristine MoSe2 in an acidic medium and demonstrated a superior HER catalytic activity compared to the state-of-the-art Pt/C catalyst, particularly at a high current density beyond ca. 55 mA cm-2. Additionally, the MoSe2-Gr catalyst demonstrated long-term electrochemical stability during HER. This work, thus, presents a facile and novel approach for obtaining an efficient MoSe2 electrocatalyst applicable in green hydrogen production.

High current density hydrogen evolution on heterostructured Ni/Cr bimetallic sulfide catalyst in alkaline media

It remains challenging to design alkaline hydrogen evolution reaction (HER) electrocatalyst able to stably operate at ampere-level current density. In this work, we successfully synthesized heterostructured Ni3S2/Cr2S3 nanosheets on nickel foam (Ni3S2/Cr2S3/NF) for high current HER electrocatalysis in alkaline media. As-prepared Ni3S2/Cr2S3/NF reaches 0.5 and 1.0 A cm−2 currents at 230 and 333 mV overpotential, respectively. After 50 h test at 0.5 A cm−2, the potential of Ni3S2/Cr2S3/NF remained almost unchanged. This impressive HER performance stems from its unique hybridization nature enabled hydrogen spillover, in which Cr2S3 efficiently catalyzes the Volmer step, i.e., water dissociation to generate hydrogen, and the latter further transports to neighboring Ni3S2 via spillover to facilitate the molecular hydrogen formation. This work provides a feasible strategy to synthesize efficient and durable HER catalysts for ampere-level water splitting.

Self-supported amorphous phosphide catalytic electrodes for electrochemical hydrogen production coupling with methanol upgrading

Efficient catalytic electrodes for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) are pivotal for massive production of green hydrogen from water electrolysis, and the further replacement of kinetically sluggish OER by tailored elecrooxidation of certain organics is a promising way to co-produce hydrogen and value-added chemicals via a more energy-saving and safer manner. Herein, amorphous Ni-Co-Fe ternary phosphides (NixCoyFez-Ps) with different Ni:Co:Fe ratios electrodeposited onto Ni foam (NF) substrate were served as self-supported catalytic electrodes for alkaline HER and OER. The Ni4Co4Fe1-P electrode deposited in solution at Ni:Co:Fe ratio of 4:4:1 displayed low overpotential (61 mV at −20 mA cm−2) and acceptable durability for HER, while the Ni2Co2Fe1-P electrode fabricated in deposition solution at Ni:Co:Fe ratio of 2:2:1 showed good OER efficiency (overpotential of 275 mV at 20 mA cm−2) and robust durability, the further replacement of OER by anodic methanol oxidation reaction (MOR) enabled selective production of formate with 110 mV lower anodic potential at 20 mA cm−2. The HER-MOR co-electrolysis system based on Ni4Co4Fe1-P cathode and Ni2Co2Fe1-P anode could save 1.4 kWh of electric energy per cubic meter of H2 relative to mere water electrolysis. The current work offers a feasible approach to co-produce H2 and value-upgraded formate via an energy-saving manner by rational design of catalytic electrodes and construction of co-electrolysis system, and paves the way for cost-effective co-preparation of more value-added organics and green hydrogen via electrolysis.