Hierachical Aerogel-Supported Cu–Sn–O_x Solid Solutions for Highly Selective CO₂ Electroreduction and Zn–CO₂ Batteries

Abstract

The electrochemical CO 2 reduction reaction (CO 2 RR) into high-value carbon compounds such as CO and HCOOH is a promising strategy for the utilization and conversion of emitted CO 2 . However, the selectivity of the CO 2 RR for HCOOH is typically less than 90% and operates within a narrow voltage range, which limits its practical application. Herein, we propose a novel heterostructural aerogel as a highly efficient electrocatalyst for CO 2 RR to HCOOH. This catalyst consists of Cu−Sn−O x solid solutions embedded in a reduced graphene oxide matrix (Cu−Sn− O x /rGO). The incorporation of Cu 2+ into the SnO 2 matrix enhances HCOOH production by improving the adsorption of the *OCHO intermediate and inhibiting H 2 evolution, as confirmed by in situ measurements and computational studies. As a result, Cu−Sn−O x /rGO achieves a remarkable Faradaic efficiency (FE) of up to 91.4% for HCOOH and maintains high selectivity over a broad operating voltage range (−0.8 to −1.1 V). Additionally, the assembled Zn−CO 2 batteries demonstrated an excellent power density of 1.14 mW/cm 2 and exceptional stability for over 25 h.