阿德莱德大学Shi-Zhang Qiao团队发现通过改性第一和第二配位球可以调整单原子催化剂上的酸性氧还原选择性。相关研究成果于2021年5月13日发表在国际顶尖学术期刊《美国化学会杂志》。

多电子电催化反应的产物选择性对能量转换效率和化学生产至关重要。然而，目前的一个实际缺点是对实际催化活性中心的了解有限。

该文以酸性氧还原反应（ORR）中的单原子催化剂（SAC）为原型，报道了催化剂的结构-性质关系，首次揭示了分子水平的局部结构，包括第一和第二配位球（CSs），而不是单个活性原子，协同决定电催化反应。Co-SAC上的ORR选择性可以通过改变第一（N或/和O配位）和第二（C–O–C基团）CSs从四电子途径调整为双电子途径。

综合理论预测和实验，包括X射线吸收精细结构分析和原位红外光谱分析，研究人员证实了这种独特的选择性变化源于活性中心从Co原子到O原子的结构依赖性转移。该研究表明其可以优化了活性中心的电子结构和*OOH吸附行为，使酸性H2O2电合成达到“最佳”活性和选择性>95%。

附：英文原文

Title: Tailoring Acidic Oxygen Reduction Selectivity on Single-Atom Catalysts via Modification of First and Second Coordination Spheres

Author: Cheng Tang, Ling Chen, Haijing Li, Laiquan Li, Yan Jiao, Yao Zheng, Haolan Xu, Kenneth Davey, Shi-Zhang Qiao

Issue&Volume: May 13, 2021

Abstract: Product selectivity in multielectron electrocatalytic reactions is crucial to energy conversion efficiency and chemical production. However, a present practical drawback is the limited understanding of actual catalytic active sites. Here, using as a prototype single-atom catalysts (SACs) in acidic oxygen reduction reaction (ORR), we report the structure–property relationship of catalysts and show for the first time that molecular-level local structure, including first and second coordination spheres (CSs), rather than individual active atoms, synergistically determines the electrocatalytic response. ORR selectivity on Co-SACs can be tailored from a four-electron to a two-electron pathway by modifying first (N or/and O coordination) and second (C–O–C groups) CSs. Using combined theoretical predictions and experiments, including X-ray absorption fine structure analyses and in situ infrared spectroscopy, we confirm that the unique selectivity change originates from the structure-dependent shift of active sites from the center Co atom to the O-adjacent C atom. We show this optimizes the electronic structure and *OOH adsorption behavior on active sites to give the present “best” activity and selectivity of >95% for acidic H2O2 electrosynthesis.

DOI: 10.1021/jacs.1c03135

Source: https://pubs.acs.org/doi/10.1021/jacs.1c03135