X射线吸收光谱法
密度泛函理论
电子结构
催化作用
材料科学
氧烷
拉曼光谱
析氧
电化学
镍
反应性(心理学)
费米能级
金属
化学
化学物理
吸收光谱法
结晶学
光谱学
物理化学
计算化学
医学
生物化学
物理
替代医学
电极
量子力学
病理
光学
冶金
电子
作者
Roger Sanchis-Gual,Diego Hunt,Camilo Jaramillo,Álvaro Seijas-Da Silva,Martín Mizrahi,Carlo Marini,Víctor Oestreicher,Gonzalo Abellán
标识
DOI:10.26434/chemrxiv-2023-r5zqx
摘要
Nickel-based layered hydroxides (LHs) are a family of efficient electrocatalysts for the alkaline oxygen evolution reaction (OER). Nevertheless, fundamental aspects such as the influence of the crystalline structure and the role of lattice distortion of the catalytic sites remain poorly understood and typically muddled. Herein, we carried out a comprehensive investigation on ɑ-LH, β-LH and LDH phases, analysing the role exerted by Ni-vacancies by means of structural, spectroscopical, in-silico and electrochemical studies. Indeed, density functional theory (DFT) calculations, in agreement with X-ray absorption spectroscopy (XAS), confirm that the presence of Ni-vacancies produces acute distortions of the electroactive Ni sites (shortening in the Ni-O distances and changes in the O-Ni-O angles), triggering the appearance of Ni localised electronic states on the Fermi level, reducing of Egap, and therefore increasing the reactivity of the electroactive sites. Furthermore, post-mortem Raman and XAS measurements unveil the transformation of ɑ-LH phase into a highly reactive oxyhydroxide-like structure stable under ambient conditions. Hence, this work pinpoints the critical role of cationic vacancies on the structural and electronic properties of the LH structures, which controls their inherent reactivity towards OER catalysis. We envision Ni-based ɑ-LH as a perfect platform for trivalent cations hosting, closing the gap toward the next generation of benchmark efficient earth-abundant electrocatalysts.
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