Durability For Hydrogen Evolution Reaction Research Articles

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.

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.

Ion-sharing interface and directional doping synergize N-MoS2/Se-CoS2 catalyst for efficient hydrogen evolution

Interfacing and doping can effectively harmonize the electronic and coordination states of active centers in the electrocatalysts. Herein, we prepare heterostructured N-MoS2/Se-CoS2 electrocatalyst with ion-sharing interfaces and directional doping to activate inert basal phases for hydrogen evolution reaction (HER). Based on experimental and theoretical results, their synergistic effects on electron redistribution, electronic structure and coordination chemistry are investigated; furthermore, roles of each component and bridged Mo-S-Co sites at the phase interfaces as active sites in optimizing the adsorption/desorption of essential reaction intermediates H* and OH–, as well as the free energies of unit reaction steps in the HER, are elucidated in depth. The N-MoS2/Se-CoS2 catalyst needs only 37 mV to give current density of 10 mA cm−2 with a low Tafel slope of 49.4 mV dec−1; more importantly, the catalyst delivers a long-term durability for HER in alkaline condition and comparable performance with commercial RuO2||Pt/C system in a two-electrode assembled electrolyzer. This work provides more insights into the design and preparation of high-performance heterostructured electrocatalysts.

Ru branched nanostructure on porous carbon nanosheet for superior hydrogen evolution over a wide pH range

Water-electrolytic hydrogen production has attracted extensive attention due to it can fully utilize renewable energy sources and residual secondary energy, while the sluggish kinetics reaction rate seriously hinders the hydrogen evolution reaction (HER) progress. Herein, we reported a novel and simple precipitation-calcination method for the synthesis of Ru branched nanostructures on porous N-doping carbon nanosheets (Ru BCNNs/PNC NNSs) with rough surface and step and edge atoms. The overpotentials for Ru BCNNs/PNC NNSs are 33.4 mV, 81.3 mV, and 99.9 mV in acidic, alkaline, and neutral media, respectively, to achieve the current density of 10 mA cm−2, indicating the superior HER performance over a wide pH range due to the unique rough surfaces and abundant of steps and edges atoms. Meanwhile, the Tafel slopes are 21.7 mV dec−1, 111.1 mV dec−1, and 104.7 mV dec−1 for Ru BCNNs/PNC NNSs in 1.0 M HClO4, 1.0 M KOH, and 1.0 M phosphate buffer solution (PBS, pH=7.0), respectively, much lower than that of commercial Pt/C catalysts with mass loading of 10 % from Macklin Inc. (Pt/C-MK). Furthermore, due to the advantages of the strong interface binding energy between Ru and N-C, the Ru BCNNs/PNC NNSs show outstanding durability for HER not only in mild conditions but also in harsh conditions, outperforming most Ru-based electrocatalysts reported previously.

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

The scarcity and high cost of PGM electrocatalysts are the key bottleneck in the mass-scale commercialization of many electrolysis technologies. Bifunctional single-atom electrocatalysts (SACs) are promising alternatives for PGM electrocatalysts in next-generation electrolysis technologies because of their superior intrinsic activity and perfect atom utilization. Regulating the coordination environment of platinum atomic sites identifies their electrocatalytic performance. Therefore, exploring more appropriate supports could facilitate the construction of active and durable electrocatalysts with ultralow noble metal content. Herein, we report on a reliable approach for producing a novel type of SACs composed of atomically dispersed Pt active sites stabilized on defective NiCo layered double hydroxide (Pt/D-NiCo LDH) nanosheets as an ultralow-Pt hybrid electrocatalyst for hydrogen evolution reaction (HER), urea oxidation reaction (UOR), and full urea-water electrolysis. The optimized Pt1/D-NiCo LDH-24 SAC displays a remarkable HER and UOR performance where it yields a current density of 10 mA cm−2 at 37 mV and 1.25 V vs. RHE for HER and UOR, respectively. Symmetrical urea electrolyzer constructed of Pt1/D-NiCo LDH-24 electrodes attains 10 mA cm−2 at a cell voltage of 1.32 V vs. RHE, demonstrating superior activity and durability over 60 h operation when compared to commercial Pt/C(+)‖RuO2(−) system.

Direct Evidence of the Role of Co or Pt, Co Single-Atom Promoters on the Performance of MoS2 Nanoclusters for the Hydrogen Evolution Reaction

Developing alternatives to platinum (Pt) and iridium (Ir) in proton-exchange membrane water electrolyzers is crucial on the way to viable energy provision schemes. However, although it seems difficult to substitute Ir, alternatives exist for Pt at the proton-exchange membrane water electrolyzer cathode. Here, we report on the synthesis and the characterization of efficient and durable hydrogen evolution reaction (HER) nanocatalysts based on MoS2 supported on high-surface-area carbon. Citric acid was used as a chelating agent to control the size of the MoS2 crystallites (1.4 nm) and thus the density of active sites (slab edges). Inspired by successful approaches in catalysis for hydrodesulfurization reactions, conventional 2H MoS2 was sequentially doped with cobalt (Co) and then with 1 wt % of Pt. Overpotentials of 188, 140, and 118 mV at 10 mA cm–2 are reported for MoS2/C, Co–MoS2/C, and Pt1%–CoMoS2/C, respectively. This result is attributed to the weakening of the Hads binding energy of the promoted MoS2-edge active sites (because the promoting atoms are mostly located at the edges). Associated with small-metal dissolution rates (monitored in situ, during the HER), our findings demonstrate that metal promotion (doping) is a promising route to replace Pt with earth-abundant elements in acidic water electrolyzers.

Carbon layer-protected self-supporting CoSe2 nanowire arrays for durable hydrogen evolution reaction catalysts

Carbon layer-covered CoSe2 nanowire arrays grown on carbon cloth (C@CoSe2/CC), which promote electrolyte penetration, accelerate the diffusion of H2 bubbles and prevents CoSe2 from acid etching, and give rise to improved HER activity and superior durability.