Mechanistic Insights and Advances in Electrode/Electrolyte Interfaces for Efficient Electrocatalytic CO₂ Reduction to C₂ Products

ABSTRACT Electrocatalytic CO 2 reduction (ECR) is a promising approach to converting CO 2 into chemicals and fuels. Among the ECR products, C 2 products such as ethylene, ethanol, and acetate have been extensively studied due to their high industrial demands. However, the mechanistic understanding of C 2 product formation remains unclear due to the lack of in situ or operando measurements that can observe the complex and instantaneous atomic evolutions of adsorbates at the electrode/electrolyte interface. Moreover, the sensitivity of ECR reactions to variations at the interface further widens the gap between mechanistic understanding and performance enhancement. To bridge this gap, first‐principle studies provide insights into how the interface influences ECR. In this study, we present a review of mechanistic studies investigating the effects of various factors at the interface, with an emphasis on the C 2 product formation. We begin by introducing ECR and the essential metrics. Next, we discuss the factors classified by their components at the interface, namely, electrocatalyst, electrolyte, and adsorbates, respectively, and their effects on the C 2 product formation. Due to the interplay among these factors, we aim to deconvolute the influence of each factor and clearly demonstrate their impacts. Finally, we outline the promising directions for mechanistic studies of C 2 products.