The Role of Undercoordinated Sites on Zinc Electrodes for CO<sub>2</sub> Reduction to CO
Mavis Pei Lin Kang, Manuel J. Kolb, Federico Calle‐Vallejo, Boon Siang Yeo
Abstract
Abstract The electrochemical CO 2 reduction reaction (CO 2 RR) using renewable energies is a promising route toward global carbon neutrality. Recently, the use of copper catalysts and CO feedstocks, instead of CO 2 , has been shown to enhance the selectivity toward multicarbon products, leading to increased efforts in developing tandem electrocatalytic systems. State‐of‐the‐art CO 2 ‐to‐CO electrocatalysts are mainly based on noble metals such as silver and gold. Earth‐abundant zinc, in contrast, displays poorer selectivity and activity. Herein, the use of porous dendritic oxidederived zinc (OD‐Zn) catalysts for CO 2 RR is reported. These catalysts can reduce CO 2 to CO with a maximum Faradaic efficiency of 86% at −0.95 V versus reversible hydrogen electrode (RHE) and partial current density of −266 mA cm –2 at −1.00 V vs RHE. OD‐Zn is further found to have a higher amount of undercoordinated sites and exhibits higher CO 2 RR activity and CO selectivity than electrodeposited Zn metal. While oxygen vacancies have been previously implicated as active sites, detailed experiments and density functional theory calculations show that Zn sites with a high degree of undercoordination provide even higher activity, in view of their nearly optimal *COOH adsorption energies. These findings showcase Zn‐Oderived particles with plentiful undercoordinated sites as cost‐effective electrocatalysts for CO production.