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<p>Transition metal Ni is a classic hydrogen evolution catalyst and the alkaline media is more&#xa0;advantageous to the hydrogen evolution reaction (HER) catalyzed by Ni. However, the alkaline hydrogen evolution mechanism on Ni and the influence mechanism of OH<sup>−</sup> on its activity are still undiscovered. Therefore, in this paper, the hydrogen evolution mechanisms of Ni surface in alkaline media were revealed using the density functional theory (DFT) method. Our calculations show that promoting H<sub>2</sub>O dissociation by OH<sup>−</sup> is the major cause for the high alkaline hydrogen evolution activity of Ni. However, OH<sup>−</sup> is unfavorable to H<sub>ads</sub> desorption. Without the applied potential, the HER on bare Ni follows the H<sub>2</sub>O dissociation-determined Volmer-Tafel mechanism and that on Ni-*OH<sup>−</sup> should include the H<sub>2</sub>O dissociation, H migration, and Tafel steps, and the Tafel step is the rate determining step. Increasing the reduction potential cause that the barrier of Heyrovsky steps decrease and that of Tafel step increase. At − 0.5&#xa0;V and − 0.8&#xa0;V vs SHE, the Tafel and Heyrovsky step are the RDS of HER on Ni in alkaline solution, respectively.</p>

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Hydrogen evolution mechanism on Ni surface in alkaline solution: a DFT study

  • 期刊论文

  • 发表日期：

    2025年9月3日

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  • Yanxia Han,
  • Penji Yan,
  • Chao Kong

摘要

Transition metal Ni is a classic hydrogen evolution catalyst and the alkaline media is more advantageous to the hydrogen evolution reaction (HER) catalyzed by Ni. However, the alkaline hydrogen evolution mechanism on Ni and the influence mechanism of OH− on its activity are still undiscovered. Therefore, in this paper, the hydrogen evolution mechanisms of Ni surface in alkaline media were revealed using the density functional theory (DFT) method. Our calculations show that promoting H2O dissociation by OH− is the major cause for the high alkaline hydrogen evolution activity of Ni. However, OH− is unfavorable to Hads desorption. Without the applied potential, the HER on bare Ni follows the H2O dissociation-determined Volmer-Tafel mechanism and that on Ni-*OH− should include the H2O dissociation, H migration, and Tafel steps, and the Tafel step is the rate determining step. Increasing the reduction potential cause that the barrier of Heyrovsky steps decrease and that of Tafel step increase. At − 0.5 V and − 0.8 V vs SHE, the Tafel and Heyrovsky step are the RDS of HER on Ni in alkaline solution, respectively.