Bao Zhang, Jia Yao, Jia Liu, Tao Zhang, Houzhao Wan and Hao Wang
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By introducing a combination of a high surface reactivity metal (Mo) and a low surface reactivity metal (Cu/Zn) into Ni alloys, this surface reactivity diversity approach can significantly accelerate HER kinetics and allows for favorable adsorption of hydrogen and hydroxyl species at different pH levels. The resulting NiCuMo medium-entropy alloy exhibited impressive HER performance, with an overpotential of 63 mV at a current density of 100 mA cm<small><sup>−2</sup></small> in alkaline electrolyte and 115 mV in neutral electrolyte. The intrinsic neutral HER activity of this NiCuMo is 3.65 times that of the benchmark alkaline HER catalyst. Furthermore, the NiCuMo-based membrane electrode assembly water electrolyzer can be stably operated for at least 200 h at a larger current density of 1.5 A cm<small><sup>−2</sup></small>. This surface reactivity diversity approach presents a promising design framework for less pH-dependent electrocatalysis.</p>","PeriodicalId":72877,"journal":{"name":"EES catalysis","volume":" 6","pages":" 1017-1024"},"PeriodicalIF":0.0000,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Reducing the pH dependence of hydrogen evolution kinetics via surface reactivity diversity in medium-entropy alloys†\",\"authors\":\"Bao Zhang, Jia Yao, Jia Liu, Tao Zhang, Houzhao Wan and Hao Wang\",\"doi\":\"10.1039/D3EY00157A\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >The water dissociation step of the hydrogen evolution reaction is a well-known pH-dependent process, which makes sustainable hydrogen production suffer from sluggish kinetics. Herein, we demonstrate a surface reactivity diversity approach to reduce the pH dependence of HER kinetics in medium-entropy alloys. Grand canonical potential based calculation, CO-oxidation and potential of zero charge results showed that shifts in the Fermi level in neutral electrolytes lead to stronger M–H bonding (M = Ni, Pt, <em>etc.</em>) compared to those in basic solutions. These pH-dependent binding energies disrupt the optimized adsorption strength of advanced alkaline HER catalysts. By introducing a combination of a high surface reactivity metal (Mo) and a low surface reactivity metal (Cu/Zn) into Ni alloys, this surface reactivity diversity approach can significantly accelerate HER kinetics and allows for favorable adsorption of hydrogen and hydroxyl species at different pH levels. The resulting NiCuMo medium-entropy alloy exhibited impressive HER performance, with an overpotential of 63 mV at a current density of 100 mA cm<small><sup>−2</sup></small> in alkaline electrolyte and 115 mV in neutral electrolyte. The intrinsic neutral HER activity of this NiCuMo is 3.65 times that of the benchmark alkaline HER catalyst. Furthermore, the NiCuMo-based membrane electrode assembly water electrolyzer can be stably operated for at least 200 h at a larger current density of 1.5 A cm<small><sup>−2</sup></small>. 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引用次数: 0
摘要
析氢反应的水解离步骤是一个众所周知的ph依赖过程,这使得可持续制氢的动力学缓慢。在此,我们展示了一种表面反应性多样性方法来降低中等熵合金中HER动力学的pH依赖性。基于大规范电位的计算、co氧化和零电荷电位的结果表明,中性电解质中费米能级的变化导致M - h键(M = Ni, Pt等)比碱性溶液中更强。这些依赖于ph的结合能破坏了高级碱性HER催化剂的最佳吸附强度。通过将高表面反应性金属(Mo)和低表面反应性金属(Cu/Zn)结合到Ni合金中,这种表面反应性多样性方法可以显著加快HER动力学,并允许在不同pH水平下对氢和羟基进行有利的吸附。所得NiCuMo中熵合金表现出令人印象深刻的HER性能,在碱性电解质中电流密度为100 mA cm - 2时过电位为63 mV,在中性电解质中过电位为115 mV。NiCuMo的固有中性HER活性是基准碱性HER催化剂的3.65倍。此外,基于nicumo的膜电极组件水电解槽可以在1.5 a cm−2的较大电流密度下稳定运行至少200小时。这种表面反应性多样性方法为较少依赖ph的电催化提供了一个有前途的设计框架。
Reducing the pH dependence of hydrogen evolution kinetics via surface reactivity diversity in medium-entropy alloys†
The water dissociation step of the hydrogen evolution reaction is a well-known pH-dependent process, which makes sustainable hydrogen production suffer from sluggish kinetics. Herein, we demonstrate a surface reactivity diversity approach to reduce the pH dependence of HER kinetics in medium-entropy alloys. Grand canonical potential based calculation, CO-oxidation and potential of zero charge results showed that shifts in the Fermi level in neutral electrolytes lead to stronger M–H bonding (M = Ni, Pt, etc.) compared to those in basic solutions. These pH-dependent binding energies disrupt the optimized adsorption strength of advanced alkaline HER catalysts. By introducing a combination of a high surface reactivity metal (Mo) and a low surface reactivity metal (Cu/Zn) into Ni alloys, this surface reactivity diversity approach can significantly accelerate HER kinetics and allows for favorable adsorption of hydrogen and hydroxyl species at different pH levels. The resulting NiCuMo medium-entropy alloy exhibited impressive HER performance, with an overpotential of 63 mV at a current density of 100 mA cm−2 in alkaline electrolyte and 115 mV in neutral electrolyte. The intrinsic neutral HER activity of this NiCuMo is 3.65 times that of the benchmark alkaline HER catalyst. Furthermore, the NiCuMo-based membrane electrode assembly water electrolyzer can be stably operated for at least 200 h at a larger current density of 1.5 A cm−2. This surface reactivity diversity approach presents a promising design framework for less pH-dependent electrocatalysis.