Chainlike Mesoporous SnO2 as a Well-Performing Catalyst for Electrochemical CO2 Reduction

: In this Article, we present an easy, quick, and scalable route, based on anodic oxidation, for the preparation of mesoporous SnO2 as an efficient electrocatalyst for the CO2 reduction reaction (CO2RR). Crystallographically interconnected SnO2 nanocrystals with abundant grain boundaries, high specific surface area, and easily accessible porosity result to be active and selective for the CO2RR. This electrocatalyst shows faradaic efficiency (FE) of about 95% at −0.97 and −1.06 V versus reversible hydrogen electrode (RHE) toward the formation of predominant HCOOH and minor CO. A peak FE value of 82% for the HCOOH production is obtained at −1.06 V vs RHE. High HCOOH partial current densities of 10.2 and 15.3 mA cm−2 are observed at −0.97 and −1.15 V vs RHE, respectively. Thorough electrochemical characterizations demonstrate that the synthesized SnO2-based gas diffusion electrode allows efficient diffusion of CO2 even at high kinetics because of the highly open porous structure. The good understanding of the catalyst behavior is achieved also after the electrode testing, and it shows that the proposed preparation route results in a stable and durable material. The here reported promising results can be exploited for developing high-performance and sustainable electrocatalysts with a high potentiality to be implemented in real CO2 conversion devices.