新加坡南阳理工大学Bin Liu团队报道了轴向氧配位单Sn原子电化学还原CO₂的操作数光谱分析。相关研究成果发表在2023年3月6日出版的国际知名学术期刊《美国化学会杂志》。

Sn基材料已被证明是用于选择性电化学CO₂还原反应（CO₂RR）的有前途的催化剂。然而，催化中间体和关键表面物种的详细结构仍有待确定。

该文中，研究人员开发了一系列具有明确结构的单Sn原子催化剂作为模型系统，以探索其对CO₂RR的电化学反应性。在Sn单原子位点上CO₂还原成甲酸的选择性和活性与Sn（IV）-N4部分与氧（O–Sn–N4）轴向配位相关，在1.0V vs可逆氢电极（RHE）下，达到89.4%的最佳HCOOH法拉第效率，部分电流密度（jHCOOH）为74.8 mA·cm^–2。使用操作性X射线吸收光谱、衰减全反射表面增强红外吸收光谱、拉曼光谱和119Sn穆斯堡尔光谱的组合，在CO₂RR期间捕获了表面结合的双齿碳酸锡物种。此外，还测定了反应条件下单个Sn原子物种的电子结构和配位结构。

密度泛函理论（DFT）计算进一步支持Sn–O–CO₂物种在O–Sn–N4位点上的优选形成，与在Sn–N3位点上优选形成*COOH物种相比，这有效地调节了反应中间体的吸附构型，并降低了*OCHO物种氢化的能垒，从而大大促进CO₂到HCOOH的转化。

附：英文原文

Title: Operando Spectroscopic Analysis of Axial Oxygen-Coordinated Single-Sn-Atom Sites for Electrochemical CO2 Reduction

Author: Yachen Deng, Jian Zhao, Shifu Wang, Ruru Chen, Jie Ding, Hsin-Jung Tsai, Wen-Jing Zeng, Sung-Fu Hung, Wei Xu, Junhu Wang, Frédéric Jaouen, Xuning Li, Yanqiang Huang, Bin Liu

Issue&Volume: March 6, 2023

Abstract: Sn-based materials have been demonstrated as promising catalysts for the selective electrochemical CO2 reduction reaction (CO2RR). However, the detailed structures of catalytic intermediates and the key surface species remain to be identified. In this work, a series of single-Sn-atom catalysts with well-defined structures is developed as model systems to explore their electrochemical reactivity toward CO2RR. The selectivity and activity of CO2 reduction to formic acid on Sn-single-atom sites are shown to be correlated with Sn(IV)-N4 moieties axially coordinated with oxygen (O–Sn–N4), reaching an optimal HCOOH Faradaic efficiency of 89.4% with a partial current density (jHCOOH) of 74.8 mA·cm–2 at 1.0 V vs reversible hydrogen electrode (RHE). Employing a combination of operando X-ray absorption spectroscopy, attenuated total reflectance surface-enhanced infrared absorption spectroscopy, Raman spectroscopy, and 119Sn Mssbauer spectroscopy, surface-bound bidentate tin carbonate species are captured during CO2RR. Moreover, the electronic and coordination structures of the single-Sn-atom species under reaction conditions are determined. Density functional theory (DFT) calculations further support the preferred formation of Sn–O–CO2 species over the O–Sn–N4 sites, which effectively modulates the adsorption configuration of the reactive intermediates and lowers the energy barrier for the hydrogenation of *OCHO species, as compared to the preferred formation of *COOH species over the Sn–N4 sites, thereby greatly facilitating CO2-to-HCOOH conversion.

DOI: 10.1021/jacs.2c12952

Source: https://pubs.acs.org/doi/10.1021/jacs.2c12952