Indium Metal Oxide Tandem Ag Catalyst toward Highly Selective CO<sub>2</sub> Electroreduction to CO over a Wide Potential Window
Zongxia Duan, Weiwei Guo, Zijian Fang, Guixian Xie, Guoliang Mei, Xianzhen Lang, Doudou Liu, Yanling Zhai, Xiaoquan Lu
Abstract
We report In 2 O 3 tandem Ag-based catalysts for an electrochemical CO 2 reduction reaction (eCO 2 RR), which achieve remarkable selectivity toward CO and desirable Faradaic efficiencies (FEs) exceeding 90%, with a maximum value of 97.8%, achieved over 12.25%In 2 O 3 –Ag using the H-type cell within a wide potential window ranging from −0.48 to −0.88 V vs RHE. Moreover, a high current density of −102.6 mA cm –2 can be attained in the flow cell while maintaining an FE of CO above 90%. The theoretical calculations show a more negative Gibbs free energy for the formation of the key intermediate *CO 2 – on the In site, which demonstrates that In 2 O 3 of the tandem catalyst exhibits a stronger adsorption and activation capacity for CO 2 . Additionally, DFT simulation reveals the thermodynamic feasibility of the surface transport of *CO 2 –, wherein the *CO 2 – intermediate migrates from the In site to the Ag site. The rapid electron transfer at the In 2 O 3 –Ag heterointerface influences the electronic environment of the Ag site, accelerating migration and reducing the energy barrier for *CO 2 – conversion to *COOH, ultimately facilitating the generation of CO.