β-NiOOH 的结构和析氧活性：质子在哪里？,ACS Catalysis

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β-NiOOH 的结构和析氧活性：质子在哪里？
ACS Catalysis ( IF 11.3 ) Pub Date : 2021-12-15 , DOI: 10.1021/acscatal.1c04647
Qi Hu _{1,

2} , Yufeng Xue ₂ , Jianxin Kang ₃ , Ivan Scivetti _{4,

5} , Gilberto Teobaldi _{6,

7} , Annabella Selloni ₈ , Lin Guo ₃ , Li-Min Liu ₂

Affiliation

Ni氧化物和羟基氧化物（NiO _x）作为碱性电池的阴极材料和析氧反应（OER）的电催化剂已经被研究了很长时间。然而，对其原子和电子结构与电化学性能或稳定性之间的联系的理解仍然不完整。在这项工作中，我们使用第一性原理密度泛函理论 (DFT) 计算来重新审视 β-NiOOH（NiO _x的催化活性相）的结构、电子特性和 OER 活性。经过广泛的基于 DFT 的筛选，我们确定了一种迄今为止被忽视的结构，其特征是 H 原子在 NiO ₂层上的均匀分布。该结构中的所有 Ni ³⁺阳离子表现出相同的 t_g⁶ e _g¹电子构型，占据 3d _z²轨道。将计算的键长与扩展的 X 射线吸收精细结构 (EXAFS) 数据进行比较，明确支持相对于所有其他低能配置的这种结构。基于这种结构，我们揭示并详细说明了基础 β-NiOOH (001) 表面上以缺陷为主的 OER 机制，过电位低至 0.39 V。目前的结果应该为理解和开发增强过渡的持续努力提供有价值的贡献-用于OER的金属氢氧化物催化剂。

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Structure and Oxygen Evolution Activity of β-NiOOH: Where Are the Protons?

Ni oxides and oxyhydroxides (NiO_x) have been studied for a long time as cathode materials for alkaline batteries and electrocatalysts for the oxygen evolution reaction (OER). Yet, understanding of the connection between their atomic and electronic structures and electrochemical performance or stability is still incomplete. In this work, we use first-principles density functional theory (DFT) calculations to revisit the structure, electronic properties, and OER activity of β-NiOOH, the catalytically active phase of NiO_x. Following extensive DFT-based screening, we identify a hitherto overlooked structure characterized by a uniform distribution of H atoms on the NiO₂ layers. All the Ni³⁺ cations in this structure exhibit an identical t_g⁶e_g¹ electronic configuration with an occupied 3d_z² orbital. Comparison of the calculated bond lengths with extended X-ray absorption fine structure (EXAFS) data unequivocally supports this structure relative to all other low-energy configurations. Based on this structure, we uncover and detail defect-dominated OER mechanisms on the basal β-NiOOH (001) surface, with overpotentials as low as 0.39 V. The present results should provide a valuable contribution to ongoing efforts for understanding and developing enhanced transition-metal hydroxide catalysts for the OER.

更新日期：2022-01-07

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