Efficient CO 2 ‐To‐HCOOH Conversion at Industrial Current Density in Strong Acid via Synergistic Water Activation

Abstract Efficient CO 2 electroreduction to HCOOH in acidic electrolytes remains a great challenge, especially under high current density conditions. In this study, by introducing In 2 O 3 onto the SnO 2 supported on graphene surface, an In 2 O 3 /SnO 2 @rGO‐2 catalyst is constructed that achieves exceptional selectivity (≈98.3% Faradaic efficiency) for converting CO 2 into HCOOH, at a current density 700 mA cm −2 in 0.5 m K 2 SO 4 (pH 1, adjusted with H 2 SO 4 ) with a high CO 2 single‐pass conversion efficiency of 74.1%. In situ spectroscopic evidence combined with theoretical calculations demonstrates that the In 2 O 3 /SnO 2 @rGO‐2 catalyst can modulate the reaction microenvironment to regulate the initial protonation step of the CO 2 RR, thereby promoting the production of HCOOH. Furthermore, the study demonstrates continuous production of pure HCOOH for over 600 hours at 300 mA cm −2 using a solid‐electrolyte reactor with the In 2 O 3 /SnO 2 @rGO‐2 catalyst, achieving an energy conversion efficiency of 31.8%.