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Chemical Pressure-Driven Enhancement of the Hydrogen Evolving Activity of Ni2P from Nonmetal Surface Doping Interpreted via Machine Learning
Journal of the American Chemical Society ( IF 15.0 ) Pub Date : 2018-03-19 , DOI: 10.1021/jacs.8b00947
Robert B. Wexler 1 , John Mark P. Martirez 2 , Andrew M. Rappe 1
Affiliation  

The activity of Ni2P catalysts for the hydrogen evolution reaction (HER) is currently limited by strong H adsorption at the Ni3-hollow site. We investigate the effect of surface nonmetal doping on the HER activity of the Ni3P2 termination of Ni2P(0001), which is stable at modest electrochemical conditions. Using density functional theory (DFT) calculations, we find that both 2 p nonmetals and heavier chalcogens provide nearly thermoneutral H adsorption at moderate surface doping concentrations. We also find, however, that only chalcogen substitution for surface P is exergonic. For intermediate surface concentrations of S, the free energy of H adsorption at the Ni3-hollow site is -0.11 eV, which is significantly more thermoneutral than the undoped surface (-0.45 eV). We use the regularized random forest machine learning algorithm to discover the relative importance of structure and charge descriptors, extracted from the DFT calculations, in determining the HER activity of Ni2P(0001) under different doping concentrations. We discover that the Ni-Ni bond length is the most important descriptor of HER activity, which suggests that the nonmetal dopants induce a chemical pressure-like effect on the Ni3-hollow site, changing its reactivity through compression and expansion.

中文翻译:

通过机器学习解释非金属表面掺杂对 Ni2P 析氢活性的化学压力驱动增强

Ni2P 催化剂对析氢反应 (HER) 的活性目前受到 Ni3 空心位点强 H 吸附的限制。我们研究了表面非金属掺杂对 Ni2P(0001) 的 Ni3P2 末端的 HER 活性的影响,Ni2P(0001) 在适度的电化学条件下是稳定的。使用密度泛函理论 (DFT) 计算,我们发现 2 p 非金属和较重的硫属元素在中等表面掺杂浓度下都能提供接近热中性的 H 吸附。然而,我们还发现,只有表面 P 的硫属元素替代才是有效的。对于中间表面浓度的 S,在 Ni3 空心位点处 H 吸附的自由能为 -0.11 eV,这比未掺杂表面 (-0.45 eV) 的热中性要高得多。我们使用正则化随机森林机器学习算法来发现从 DFT 计算中提取的结构和电荷描述符在确定不同掺杂浓度下 Ni2P(0001) 的 HER 活性时的相对重要性。我们发现 Ni-Ni 键长是 HER 活性最重要的描述子,这表明非金属掺杂剂对 Ni3 空心位点产生类化学压力效应,通过压缩和膨胀改变其反应性。
更新日期:2018-03-19
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