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Oxygen-Inserted Top-Surface Layers of Ni for Boosting Alkaline Hydrogen Oxidation Electrocatalysis
2022-06-25 14:48

武汉大学罗威团队报道了氧插入镍表面层增强碱性氢氧化电催化性能。相关研究成果发表在2022年6月22日出版的国际学术期刊《美国化学会杂志》。

精确调整电催化剂的电子结构以获得最佳的氢氧化物结合能(OHBE)对碱性氢氧化反应(HOR)至关重要。作为铂族金属的一种很有前途的替代品,人们一直致力于开发高效的镍基碱性HOR催化剂。然而,他们的表现仍然缺乏实际竞争力。

该文中,基于分子轨道理论和Hammer–Nrskov d带模型的见解,研究人员提出了一种巧妙的表面氧插入策略,以精确定制镍电催化剂的电子结构,同时增加吸附的氢氧化物(*OH)状态和表面Ni d带之间的能级对齐度,并降低反键填充度,从而获得最佳的OHBE。在还原性气氛下,通过金属-有机框架介导的低温热解过程,得到了氧插入双原子层Ni壳层修饰的Ni金属核纳米粒子(Ni@Oi-Ni),表现出显著的碱性HOR性能,具有破记录的质量活性85.63 mA mg–1,比新合成的Ni催化剂高40倍。结合CO剥离实验与从头算计算,研究人员进一步揭示了OH-BE与插入氧含量之间的线性关系,从而导致OH结合强度与碱性HOR活性之间存在火山型相关性。

该项工作表明,氧插入顶表面层是调节镍催化剂配位环境和电子结构的有效策略,并确定了碱性HOR中OH结合强度的主导作用。

附:英文原文

Title: Oxygen-Inserted Top-Surface Layers of Ni for Boosting Alkaline Hydrogen Oxidation Electrocatalysis

Author: Yana Men, Xiaozhi Su, Peng Li, Yue Tan, Chuangxin Ge, Shuangfeng Jia, Lei Li, Jianbo Wang, Gongzhen Cheng, Lin Zhuang, Shengli Chen, Wei Luo

Issue&Volume: June 22, 2022

Abstract: Precisely tailoring the electronic structures of electrocatalysts to achieve an optimum hydroxide binding energy (OHBE) is vital to the alkaline hydrogen oxidation reaction (HOR). As a promising alternative to the Pt-group metals, considerable efforts have been devoted to exploring highly efficient Ni-based catalysts for alkaline HOR. However, their performances still lack practical competitiveness. Herein, based on insights from the molecular orbital theory and the Hammer–Nrskov d-band model, we propose an ingenious surface oxygen insertion strategy to precisely tailor the electronic structures of Ni electrocatalysts, simultaneously increasing the degree of energy-level alignment between the adsorbed hydroxide (*OH) states and surface Ni d-band and decreasing the degree of anti-bonding filling, which leads to an optimal OHBE. Through the pyrolysis procedure mediated by a metal–organic framework at a low temperature under a reducing atmosphere, the obtained oxygen-inserted two atomic-layer Ni shell-modified Ni metal core nanoparticle (Ni@Oi-Ni) exhibits a remarkable alkaline HOR performance with a record mass activity of 85.63 mA mg–1, which is 40-fold higher than that of the freshly synthesized Ni catalyst. Combining CO stripping experiments with ab initio calculations, we further reveal a linear relationship between the OHBE and the content of inserted oxygen, which thus results in a volcano-type correlation between the OH binding strength and alkaline HOR activity. This work indicates that the oxygen insertion into the top-surface layers is an efficient strategy to regulate the coordination environment and electronic structure of Ni catalysts and identifies the dominate role of OH binding strength in alkaline HOR.

DOI: 10.1021/jacs.2c01448

Source: https://pubs.acs.org/doi/10.1021/jacs.2c01448

 

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