中国科学院大连化物所彭章泉团队采用原位同位素标记光谱和理论计算解锁非质子锂-二氧化碳电池中的二氧化碳还原反应途径。相关研究成果发表在2024年6月17日出版的国际学术期刊《美国化学会杂志》。

O2还原反应(CO2RR)途径对非质子锂-CO₂电池的可逆性和过电位有重要影响；然而，由于缺乏直接的原位光谱证据，它仍然不完全被理解。

该文使用原位同位素标记光谱技术和理论计算相结合的方法，研究了模型Au|DMSO界面处的Li-CO₂RR途径。所获得的直接光谱证据表明，初级CO²RR通过在低过电位（ca.2.1 V vs Li/Li⁺）下启动的CO₂到CO途径（即2Li⁺+2CO₂+2e^–→CO+Li₂CO₃）和在高过电位（ca.1.7 V vs Li/Li⁺）下开始的CO₂到Li₂C₂O₄途径（即，2Li⁺+2CO₂+2e^-→Li₂C₂O₄）进行，其中电位依赖性途径主要取决于LiCO₂中间体的覆盖率。

同时，整个Li-CO₂RR过程也伴随着寄生反应，形成以COOH*为关键中间体的气态C₂H₄，这是由反应性LiCO₂中间体和DMSO溶剂之间的H⁺-提取反应引起的。

这些基本见解使人们能够建立非质子介质中Li-CO₂RR途径的分子图谱，并将作为可逆Li-CO₂电化学的重要指南。

附：英文原文

Title: Unlock CO2 Reduction Reaction Pathways in Aprotic Li-CO2 Batteries with In Situ Isotope-Labeled Spectroscopy and Theoretical Calculations

Author: Long Pang, Zhiwei Zhao, Tianfu Liu, Guoxiong Wang, Shaojun Dong, Zhangquan Peng

Issue&Volume: June 17, 2024

Abstract: The CO2 reduction reaction (CO2RR) pathway significantly dictates the reversibility and overpotential of aprotic Li-CO2 batteries; however, it has remained incompletely understood due to the lack of direct in situ spectroscopic evidence. Herein, the Li-CO2RR pathways at the model Au | dimethyl sulfoxide (DMSO) interface are interrogated using a combination of in situ isotope-labeled spectroscopy techniques and theoretical calculations. This obtained direct spectroscopic evidence presents that the primary CO2RR proceeds through the CO2-to-CO pathway (i.e., 2Li+ + 2CO2 + 2e– → CO + Li2CO3) initiated at a low overpotential (ca. 2.1 V vs Li/Li+), and the CO2-to-Li2C2O4 pathway (i.e., 2Li+ + 2CO2 + 2e– → Li2C2O4) initiated at a high overpotential (ca. 1.7 V vs Li/Li+), where the potential-dependent pathways critically depend on the coverage of LiCO2 intermediates. Simultaneously, the entire Li-CO2RR process is also accompanied by parasitic reactions to form gaseous C2H4 with COOH* as the crucial intermediate, which is induced by the H+-abstraction reaction between the reactive LiCO2 intermediate and the DMSO solvent. These fundamental insights enable us to establish a molecular picture for Li-CO2RR pathways in aprotic media and will serve as a crucial guideline for reversible Li-CO2 electrochemistry.

DOI: 10.1021/jacs.4c03742

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c03742