Hydrogen Evolution Reaction Overpotential Research Articles

Heterointerface-Rich Ni3N/WO3 Hierarchical Nanoarrays for Efficient Glycerol Oxidation-Assisted Alkaline Hydrogen Evolution.

Glycerol oxidation-assisted water electrolysis has emerged as a cost-effective way of co-producing green hydrogen and HCOOH. Still, preparing highly selective and stable nickel-based metal electrocatalysts remains a challenge. Herein, heterostructure Ni3N/WO3 nanosheet arrays of bifunctional catalysts with large specific surface areas loaded on nickel foam (denoted as Ni3N/WO3/NF) were synthesized. This catalyst was for glycerol oxidation reaction (GOR) and hydrogen evolution reaction (HER) with excellent catalytic performance, a voltage saving of 267 mV compared to oxygen evolution reaction (OER), and a HER overpotential of 104 mV at 100 mA cm-2. The cell voltage in the assembled GOR//HER hybrid electrolysis system reaches 100 mA cm-2 at 1.50 V, 296 mV lower than the potential required for overall water splitting. This work demonstrates that replacing GOR with OER using a cost-effective and highly active Ni-based bifunctional electrocatalyst can make hybrid water electrolysis an energy-efficient, sustainable, and green strategy for hydrogen production.

Iron Active Center Coordination Reconstruction in Iron Carbide Modified on Porous Carbon for Superior Overall Water Splitting.

In this work, a novel liquid nitrogen quenching strategy is engineered to fulfill iron active center coordination reconstruction within iron carbide (Fe3C) modified on biomass-derived nitrogen-doped porous carbon (NC) for initiating rapid hydrogen and oxygen evolution, where the chrysanthemum tea (elm seeds, corn leaves, and shaddock peel, etc.) is treated as biomass carbon source within Fe3C and NC. Moreover, the original thermodynamic stability is changed through the corresponding force generated by liquid nitrogen quenching and the phase transformation is induced with rich carbon vacancies with the increasing instantaneous temperature drop amplitude. Noteworthy, the optimizing intermediate absorption/desorption is achieved by new phases, Fe coordination, and carbon vacancies. The Fe3C/NC-550 (550 refers to quenching temperature) demonstrates outstanding overpotential for hydrogen evolution reaction (26.3mV at -10 mAcm-2) and oxygen evolution reaction (281.4 mV at 10mAcm-2), favorable overall water splitting activity (1.57 V at 10 mAcm-2). Density functional theory (DFT) calculations further confirm that liquid nitrogen quenching treatment can enhance the intrinsic electrocatalytic activity efficiently by optimizing the adsorption free energy of reaction intermediates. Overall, the above results authenticate that liquid nitrogen quenching strategy open up new possibilities for obtaining highly active electrocatalysts for the new generation of green energy conversion systems.

Microwave assisted synthesis of cobalt-doped copper selenite nanorice as bifunctional electrocatalyst for overall water splitting

In the research and development of noble-metal free catalysts, copper-based materials such as copper selenite have shown interest as electrocatalysts to drive the oxygen evolution reaction (OER) in basic medium, however their Hydrogen evolution reaction (HER) activity is still unexplored. Therefore, we have performed the synthesis of cobalt doped copper selenite nanoparticles which can robustly and effectively do electrocatalysis for both the OER and HER in basic medium electrolyte. The novelty lies in the fact that microwave synthesis procedure utilizing oxidizing agent as a key precursor is entirely new, this particular material was never employed in water splitting and catalyst need very low amount of binder. The results revealed that cobalt doped copper selenite have a relatively lower starting potential and a higher current density due to the synergistic effects of a large active area, quick charge, mass transport, and a three-dimensional conducting path, having OER and HER overpotentials of 359 mV and 226 mV at 10 mA/cm2 current densities, respectively. We found a novel doped structure featuring porous surfaces and distinctive rice like morphology which facilitate an efficient electron transportation during the water splitting thereby illustrating an exceptional performance of this system along with rapid synthesis and lower costs.

Hydrogen Evolution in Neutral Media by Differential Intermediate Binding at Charge‐Modulated Sites of a Bimetallic Alloy Electrocatalyst

AbstractThe energy barrier to dissociate neutral water has been lowered by the differential intermediate binding on the charge‐modulated metal centers of Co85Mo15 sheets supported on Ni‐foam (NF), where the overpotential for hydrogen evolution reaction (HER) in 1 M phosphate buffer solution (PBS) is only 50±9 mV at −10 mA cm−2. It has a turnover frequency (TOF) of 0.18 s−1, mass activity of 13.2 A g−1 at −200 mV vs. reversible hydrogen electrode (RHE), and produces 16 ml H2 h−1 at −300 mV vs. RHE, more than double that of 20 % Pt/C. The Moδ+ and Coδ− sites adsorb OH*, and H*, respectively, and the electron injection from Co to H−O−H cleaves the O−H bond to form the Mo−OH* intermediate. Operando spectral analyses indicate a weak H‐bonded network for facilitating the H2O*/OH* transport, and a potential‐induced reversal of the charge density from Co to the more electronegative Mo, because of the electron withdrawing Co−H* and Mo−OH* species. Co85Mo15/NF can also drive the complete electrolysis of neutral water at only 1.73 V (10 mA cm−2). In alkaline, and acidic media, it demonstrates a Pt‐like HER activity, accomplishing −1000 mA cm−2 at overpotentials of 161±7, and 175±22 mV, respectively.

Hydrogen Evolution in Neutral Media by Differential Intermediate Binding at Charge-Modulated Sites of a Bimetallic Alloy Electrocatalyst.

The energy barrier to dissociate neutral water has been lowered by the differential intermediate binding on the charge-modulated metal centers of Co85Mo15 sheets supported on Ni-foam (NF), where the overpotential for hydrogen evolution reaction (HER) in 1 M phosphate buffer solution (PBS) is only 50±9 mV at -10 mA cm-2. It has a turnover frequency (TOF) of 0.18 s-1, mass activity of 13.2 A g-1 at -200 mV vs. reversible hydrogen electrode (RHE), and produces 16 ml H2 h-1 at -300 mV vs. RHE, more than double that of 20 % Pt/C. The Moδ+ and Coδ- sites adsorb OH*, and H*, respectively, and the electron injection from Co to H-O-H cleaves the O-H bond to form the Mo-OH* intermediate. Operando spectral analyses indicate a weak H-bonded network for facilitating the H2O*/OH* transport, and a potential-induced reversal of the charge density from Co to the more electronegative Mo, because of the electron withdrawing Co-H* and Mo-OH* species. Co85Mo15/NF can also drive the complete electrolysis of neutral water at only 1.73 V (10 mA cm-2). In alkaline, and acidic media, it demonstrates a Pt-like HER activity, accomplishing -1000 mA cm-2 at overpotentials of 161±7, and 175±22 mV, respectively.

Fe–Ni-doped metal-organic framework derived CoSe2 as an efficient and stable electrocatalyst for hydrogen evolution reaction

The development of efficient, stable and low-cost catalysts for hydrogen evolution reaction (HER) is one of the major difficulties in water electrolysis. It is also the key to realizing the large-scale production of hydrogen energy, a renewable and clean energy source. In recent years, metal-organic frameworks (MOFs) have attracted much attention as novel precursors for preparing water electrolysis catalysts due to their high porosity and large specific surface area. In this paper, we use ZIF-67 as a precursor and modify it by doping transition metal elements Fe and Ni. Afterwards, Fe–Ni–CoSe2@NC is synthesized by a thermal selenization process. The results show that the HER overpotential of the catalyst after modification is reduced by 50%, and the efficiency of water electrolysis is significantly improved. Moreover, the catalyst has good stability under alkaline condition and is more economical than the expensive Pt-based catalysts, which provides more possibilities for industrial applications.

ZnMo-MOF as anti-CO hydrogen electrocatalyst enhance microbial electrosynthesis for CO/CO2 conversion

Microbial electrosynthesis (MES) is an electrically driven technology that can be used for converting CO/CO2 into chemicals. The unique electronic and substrate properties of CO make it an important research target for MES. However, CO can poison the cathode and increase the overpotential of hydrogen evolution reaction (HER), thus reducing the electron transfer rate via H2. This work evaluated the effect of an anti-CO HER catalyst on the performance of MES for CO/CO2 conversion. ZnMo-metal–organic framework (MOF) materials with different calcination temperatures were synthesized. ZnMo-MOF-800 with Mo2C nanoparticles as active centers exhibited excellent resistance to CO toxicity. It also obtained the highest hydrogen evolution and enhanced electron transfer rate in CO atmosphere. MES with ZnMo-MOF-800 cathode and Clostridium ljungdahlii as biocatalyst obtained 0.31 g L−1 d−1 acetate yield, 0.1 g L−1 d−1 butyrate yield, and 0.09 g L−1 d−1 2,3-butanediol yield in CO/CO2, while Pt/C only get 0.076 g L−1 d−1 acetate yield, 0.05 g L−1 d−1 butyrate yield and 0.02 g L−1 d−1 2,3-butanediol yield. ZnMo-MOF-800 was conducive to biofilm formation, enabling it to better resist CO toxicity. This work provides new opportunities for constructing a highly efficient cathode with an anti-CO hydrogen evolution catalyst to enhance CO/CO2 conversion in MES.

In situ anchoring of Ni12P5 on ZnIn2S4 for efficient and stable photocatalytic H2 evolution

It is a great challenge to develop efficient, stable and inexpensive hydrogen evolution reaction (HER) catalysts for photocatalytic water-splitting. In this paper, Ni12P5 (NP) was in situ anchored on the surface of ZnIn2S4 (ZIS) via a solvothermal route with nickel chloride and red phosphorus as ingredients. Using triethanolamine as sacrificial agent, the photocatalytic hydrogen evolution activity of NP/ZIS was studied under visible light irradiation. At the same time, the composition, structure, morphology and photoelectrochemical properties of the as-obtained samples were analyzed through a sequence of characterization techniques. ZIS loaded with 6 wt% NP (6NP/ZIS) exhibits the best hydrogen evolution activity and excellent stability. The H2 evolution rate of 6NP/ZIS is 5.4 times higher than that of pristine ZIS and well beyond that of the physical mixture (6NP + ZIS) or even that of the optimal Pt/ZIS under the same conditions. The maximal apparent quantum yield (AQY) of 22.7 % at 400 nm is achieved, superior to the most reported performance of ZnIn2S4-based photocatalysts for HER. The anchor of NP can not only enhance the visible light absorption intensity, but also reduce the HER overpotential. More importantly, the intimate interface between ZIS and NP can promote the separation and migration of photo-excited carriers, thereby enhancing the activity of photocatalytic hydrogen evolution. The possible photocatalytic reaction mechanism was discussed.

Intercalated PtCo Electrocatalyst of Vanadium Metal Oxide Increases Charge Density to Facilitate Hydrogen Evolution.

Efforts to develop high-performance electrocatalysts for the hydrogen evolution reaction (HER) are of utmost importance in ensuring sustainable hydrogen production. The controllable fabrication of inexpensive, durable, and high-efficient HER catalysts still remains a great challenge. Herein, we introduce a universal strategy aiming to achieve rapid synthesis of highly active hydrogen evolution catalysts using a controllable hydrogen insertion method and solvothermal process. Hydrogen vanadium bronze HxV2O5 was obtained through controlling the ethanol reaction rate in the oxidization process of hydrogen peroxide. Subsequently, the intermetallic PtCoVO supported on two-dimensional graphitic carbon nitride (g-C3N4) nanosheets was prepared by a solvothermal method at the oil/water interface. In terms of HER performance, PtCoVO/g-C3N4 demonstrates superior characteristics compared to PtCo/g-C3N4 and PtCoV/g-C3N4. This superiority can be attributed to the notable influence of oxygen vacancies in HxV2O5 on the electrical properties of the catalyst. By adjusting the relative proportions of metal atoms in the PtCoVO/g-C3N4 nanomaterials, the PtCoVO/g-C3N4 nanocomposites show significant HER overpotential of η10 = 92 mV, a Tafel slope of 65.21 mV dec-1, and outstanding stability (a continuous test lasting 48 h). The nanoarchitecture of a g-C3N4-supported PtCoVO nanoalloy catalyst exhibits exceptional resistance to nanoparticle migration and corrosion, owing to the strong interaction between the metal nanoparticles and the g-C3N4 support. Pt, Co, and V simultaneous doping has been shown by Density Functional Theory (DFT) calculations to enhance the density of states (DOS) at the Fermi level. This augmentation leads to a higher charge density and a reduction in the adsorption energy of intermediates.

Unveiling the synergistic effect of amorphous CoW-phospho-borides for overall alkaline water electrolysis

Amorphous transition-metal-phospho-borides (TMPBs) are emerging as a new class of hybrid bifunctional catalysts for water-splitting. The present work reports the discovery of CoWPB as a new promising material that adds to the smaller family of TMPBs. The optimized compositions, namely Co4WPB5 and Co2WPB1 could achieve 10 mA/cm2 at just 72 mV and 262 mV of overpotentials for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in 1 M KOH. Furthermore, the catalyst showed good performance in a 2-electrode assembly (1.59 V for 10 mA/cm2) with considerable stability (70 h stability, 10,000 operating cycles). Detailed morphological and electrochemical characterizations unveiled insights into the role of all elements in catalyst's improved performance. The presence of W was found to be crucial in improving the electronic conductivity and charge redistribution, making CoWPB suitable for both HER and OER. In computational simulation analysis, two configurations with different atomic environments, namely, CoWPBH and CoWPBO were found to have the lowest calculated overpotentials for HER and OER, respectively. It was found that the surface P-sites in CoWPBH were HER-active while the Co-sites in CoWPBO were OER-active sites. The study presents new knowledge about active sites in such multi-component catalysts that will foster more advancement in the area of water electrolysis.

Tunable decoration of Ni/Ni3N nano-heterostructures on N-defective g-C3N4 via topochemical self-nitridation for efficient electrocatalytic overall water splitting

The growth of base-metal-based heterostructures on metal-free carriers is considered an effective strategy for designing low-cost high-efficiency hybrid electrocatalysts with electronic modulation for bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), as well as further overall water splitting (OWS). Herein, Ni/Ni3N heterostructures with regulable composition are grown in-situ on N-defective graphitic carbon nitride (g-C3N4) through a novel ammonia-free topochemical self-nitridation route. Benefitting from the synergetic effect between Ni/Ni3N heterointerface and the strong support of g-C3N4 carrier, the as-fabricated Ni/Ni3N/g-C3N4 composite performs superior capacity toward both HER and OER in alkaline conditions. The optimal Ni/Ni3N/g-C3N4 sample requires low overpotentials for HER (55 mV) and OER (253 mV) to drive a current density of 10 mA cm−2, along with long-term durability. Furthermore, the constructed Ni/Ni3N/g-C3N4 (+||−) electrolytic cell for alkaline OWS can afford a current density of 10 mA cm−2 under a voltage of 1.556 V with outstanding stability.

Controlled synthesis of X (X = Mo, Cr and W) doped NiCoP nanostructures as efficient and environmentally friendly urea electrolysis catalyst

Urea electrolysis is an effective way to replace water splitting for H2 generation, which is expected to achieve carbon neutralization. However, problems such as high energy consumption and slow urea oxidation kinetics have hindered its rapid development. In this study, a series of foreign element modified NiCoP-based catalysts were in-situ grown on Ni foam through hydrothermal process, solvothermal method and low temperature phosphating method. The morphology of the electrode was regulated by changing the impregnation elements. It was found that Mo3P@NiCoP/NF has rich active sites and small impedance, which makes it have excellent urea oxidation reaction (UOR) and hydrogen evolution reaction (HER) property. At a current density of 10 mA cm−2, the potential of UOR is 1.206 V, and the overpotential of HER is 90 mV. The assembled Mo3P@NiCoP/NF / / Mo3P@NiCoP/NF cell demands only a potential of 1.285 V to drive a current density of 10 mA cm−2, and presents good durability within 12 h, which is one of the best electrochemistry activity and stability reported to date. Density functional theory suggests that NiCoP improves the reaction rate of this Mo3P@NiCoP/NF catalyst, and Mo3P enhances the metallicity of this catalyst, thereby enhancing the catalytic performance of Mo3P@NiCoP/NF.

Facilitating alkaline hydrogen evolution reaction on the hetero-interfaced Ru/RuO2 through Pt single atoms doping

Exploring an active and cost-effective electrocatalyst alternative to carbon-supported platinum nanoparticles for alkaline hydrogen evolution reaction (HER) have remained elusive to date. Here, we report a catalyst based on platinum single atoms (SAs) doped into the hetero-interfaced Ru/RuO2 support (referred to as Pt-Ru/RuO2), which features a low HER overpotential, an excellent stability and a distinctly enhanced cost-based activity compared to commercial Pt/C and Ru/C in 1 M KOH. Advanced physico-chemical characterizations disclose that the sluggish water dissociation is accelerated by RuO2 while Pt SAs and the metallic Ru facilitate the subsequent H* combination. Theoretical calculations correlate with the experimental findings. Furthermore, Pt-Ru/RuO2 only requires 1.90 V to reach 1 A cm−2 and delivers a high price activity in the anion exchange membrane water electrolyzer, outperforming the benchmark Pt/C. This research offers a feasible guidance for developing the noble metal-based catalysts with high performance and low cost toward practical H2 production.

Bifunctional phosphorus-doped NiMo oxide/Ni–Fe hydroxide composite for overall water electrolysis: optimized performance with exceptional stability

The achievement of outstanding catalytic activity in water electrolysis is contingent upon the presence of abundant active sites with enhanced kinetics in electrocatalysts. This study focuses on enhancing the catalytic activity of water electrolysis under alkaline conditions by designing P-doped NiMo oxide/Ni–Fe hydroxide composite on Ni foam through a straightforward hydrothermal process. The composite is further annealed with NaH2PO4 and subjected to induced growth via in situ precipitation in an oxalic acid solution containing Fe precursors. The resulting bifunctional catalysts exhibit notable catalytic performance, manifesting overpotentials of 20.5 mV and 69.4 mV for the hydrogen evolution reaction (HER) and 225.9 mV and 271.8 mV for the oxygen evolution reaction (OER) to drive 10 and 100 mA/cm2, respectively. The improved kinetics, attributed to P doping, play a pivotal role in reducing the overpotential of HER. Meanwhile, the homogeneous mixing of Ni and Fe, coupled with the large active surface area, enhances the catalytic performance of OER. The investigation of Mo precursors reveals their significant contribution to structurally shaping the catalysts, thereby influencing excellent OER performance. Collectively, these factors enable overall water electrolysis with low potentials of 1.82 V at 100 mA/cm2, underscoring the efficacy of the developed bifunctional catalysts.

Transforming Nature's Bath Sponge into Stacking Faults-Enhanced Ag Nanorings-Decorated Catalyst for Hydrogen Evolution Reaction.

The rational design of cost-effective and efficient electrocatalysts for electrochemical water splitting is essential for green hydrogen production. Utilizing nanocatalysts with abundant active sites, high surface area, and deliberate stacking faults is a promising approach for enhancing catalytic efficiency. In this study, we report a simple strategy to synthesize a highly efficient electrocatalyst for the hydrogen evolution reaction (HER) using carbonized luffa cylindrica as a conductive N-doped carbon skeleton decorated with Ag nanorings that are activated by introducing stacking faults. The introduction of stacking faults and the resulting tensile strain into the Ag nanorings results in a significant decrease in the HER overpotential, enabling the use of Ag as an efficient HER electrocatalyst. Our findings demonstrate that manipulating the crystal properties of electrocatalysts, even for materials with intrinsically poor catalytic activity such as Ag, can result in highly efficient catalysts. Further, applying a conductive carbon backbone can lower the quantities of metal needed without compromising the HER activity. This approach opens up new avenues for designing high-performance electrocatalysts with very low metallic content, which could significantly impact the development of sustainable and cost-effective electrochemical water-splitting systems.

Enhancing Electrocatalytic Synthesis of Glycine with CuPb1ML Electrode Synthesized via Pb UPD

AbstractIn the field of reductive organic electrosynthesis, the hydrogen evolution reaction (HER) is considered a parasitic reaction that lowers the Faradaic efficiency of the synthesis. Metals with a high overpotential for HER are often used to prevent this. However, this limits the catalytic materials that can be used in these reactions. To expand upon the scope of available electrocatalysts, we prepared a CuPb electrode via underpotential deposition (UPD). We thereby created an electrocatalyst with a single monolayer of Pb, CuPb1ML, in which Pb weight loading is only 415 ng cm−2, yet its properties could still effectively inhibit HER. The CuPb1ML electrode was used in the electrosynthesis of glycine from oxalic acid and hydroxylamine. This reaction served as a model for a C−N bond forming reaction in acidic aqueous media. The CuPb1ML electrode was compared against a pure Pb and Cu metal electrode. The CuPb1ML electrode showed a Faradaic efficiency for glycine production of 57 %, which was 9‐fold higher than Cu and rivaled the Pb electrode. The catalytic activity of CuPb1ML was 211 μmol h−1 cm−2, which is higher than both Cu and Pb. The mechanism of the electroreduction was then studied via in situ Fourier Transform Infra‐Red (FTIR) spectroscopy. These results hinted to an evolution of the electrocatalyst during the electrolysis reaction, which was then studied via Scanning Electron Microscopy (SEM) and X‐Ray Photoelectron spectroscopy (XPS). We found that the Pb monolayer restructured during catalysis, forming microparticles that were active in the reaction based on the listed experiments. Pb alloying into the lattice, which can occur during UPD, also lowered the HER, further facilitating glycine synthesis. Thus, our research also shows how Pb UPD impacts the catalytic properties of a metal both through monolayer deposition as well as surface alloying.

Optimization of Interfacial OH− Accessibility by Constructing a Delayed–Release Membrane Electrode for Ampere–Level Hydrogen Production

AbstractAchieving a high current density during electrochemical overall water splitting is a promising strategy for industrial energy conversion. The mass diffusion rate of OH− ions from the electrolyte to the interfacial active sites strongly influences the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) . Herein, the delayed‐release of OH− ions modulated by a proper organic polymer membrane on the electrode surface can optimize the OH− accessibility to the active sites (as indicated by the molecular dynamics simulations) is demonstrated and that van der Waals interaction force modulates the OH− residence time in the reaction system. The remarkable performance of the membrane‐modified electrode is achieved at ultra‐high current densities of 1.9 A cm−2 (with an HER overpotential of 602 mV) and 2 A cm−2 (with an OER overpotential of 459 mV) in 1 M KOH solution. Consequently, a super‐high current density of 1.3 A cm−2 is obtained for overall water splitting (at a voltage of only 2.2 V), which is 1.9‐fold higher than that of a benchmarked Pt/C‐IrO2 (684 mA cm−2). Therefore, the delayed‐release of OH− has optimized the mass conversion efficiency of the active sites, thus improving the electrochemical performance of overall water splitting.

Mitigating hydrogen evolution reaction and corrosion of zinc in electrically rechargeable zinc-air batteries using nanofluid electrolytes

Among various metal-air batteries, zinc-air batteries (ZABs) have received tremendous attention owing to their abundant resources, cost-free fuel from the atmosphere and ease of fabrication. The performance of ZABs depends on the bifunctional electrocatalyst deployed at the air-cathode and the hydrogen evolution reaction (HER) occurring at the anode. While the rate of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) improve the performance of ZAB, HER causes zinc corrosion and thereby affects the performance of ZAB. The corrosion of zinc is attributed to the fact that HER is thermodynamically favoured since the standard reduction potential of zinc is more negative than hydrogen. Herein, the onset and overpotential of HER are increased by the uniform dispersion of metal oxide nanoparticles in the native electrolyte (6 M KOH), thereby reducing zinc corrosion. Dispersion of 0.1 wt% of SiOx or ZnO nanoparticles increases the HER overpotential to 547 and 679 mV, respectively. The microscopic investigations confirm the inhibition of corrosion and dendritic growth of zinc. Besides these, nanofluid electrolytes enhance the kinetics of ORR and OER, thereby improving the performance of electrically rechargeable ZABs. Also, nanofluid electrolytes are stable over three months.

RuSe2/CeO2 heterostructure as a novel electrocatalyst for highly efficient alkaline hydrogen evolution

Constructing heterojunction to adjust the electronic structure of catalysts is a promising strategy for synergistically improving electrocatalytic activity. In addition, RuSe2 is recognized as an effective alternative to Pt for boosting alkaline hydrogen evolution reaction (HER) on account of its outstanding catalytic properties. Herein, novel RuSe2/CeO2 heterojunction electrocatalysts are fabricated through hydrothermal and thermal treatment methods. The optimal 50% RuSe2/CeO2 heterojunction electrocatalyst exhibits a low HER overpotential of 16 mV to attain 10 mA cm−2 current density and Tafel slope of 66.1 mV dec−1 for hydrogen evolution in 1.0 M KOH. At the same time, the 50% RuSe2/CeO2 heterojunction electrocatalyst also maintains a stable HER activity for 50 h or 3000 CV cycles. The experimental results show that formation of heterogeneous interface between RuSe2 and CeO2 results in the redistribution of electrons at the RuSe2/CeO2 interface, thereby changing the electronic structure of RuSe2 and enhancing the performance of the RuSe2/CeO2 electrocatalyst. This work may provide a feasible way to design efficient hydrogen evolution heterojunction electrocatalysts by modulating the electronic structure in alkaline electrolytes.

Three-dimensional self-supporting micro-nanostructured MoS2/CoS2/CC heterojunction derived from ZIF-67 for high efficiency electrocatalytic hydrogen evolution in both acid and alkali electrolytes

In this paper, a novel three-dimensional (3D) MoS2/CoS2 micro-nano heterostructured electrocatalyst has been successfully derived from ZIF-67 on carbon cloth (CC) by a simple method of low temperature vulcanization. The metal-organic framework (MOFs) of ZIF-67 on CC was obtained at room temperature and used as both the precursor of Co and structure template to construct the 3D self-supporting spindle CoS2 nanodiscs on CC. Large amounts of 2D MoS2 nanosheets were subsequently grown on the surface of spindle-shaped CoS2 nanodiscs to form 3D self-supporting MoS2/CoS2/CC heterostructural electrocatalyst. This 3D self-supporting heterostructural electrocatalyst showed good hydrogen evolution reaction (HER) performance in both acid and alkali electrolytes. At 10 mA/cm2, the HER overpotentials of the MoS2/CoS2/CC heterostructural electrocatalyst in the alkali and acid electrolyte were 147 mV and 119 mV, and their corresponding Tafel slopes were 90.5 mV dec−1 and 111.4 mV dec−1, respectively, indicating that this MoS2/CoS2/CC heterostructural electrocatalyst had a good application prospect in the electrolysis of water to produce hydrogen. Moreover, this work provides a new idea for low-cost, scale fabrication of 3D self-supporting heterostructured transition metal sulfide catalysts.