Sequential Phosphorus Doping and Selective Etching: A Dual‐Step Approach for CO 2 Reduction Pathway Regulation in Rhodium Catalysts

Abstract CO 2 hydrogenation is a significant way to reduce carbon emissions, but it is facing serious challenges in selectivity control. Herein, we report a sequential dual‐step surface modulation strategy comprising phosphorus (P) incorporation into CeO 2 supports followed by selective ascorbic acid (AA)‐mediated etching. This approach enables precise tuning of product selectivity while maintaining exceptional catalytic activity. The final Rh/CeO 2 ‐P‐AA catalyst exhibits a significant enhancement in the CO generation rate, reaching 1336.3 mol CO mol Rh −1 h −1 with nearly 100% CO selectivity, almost 1.9 times higher than that of Rh/CeO 2 ‐P (691.8 mol CO mol Rh −1 h −1 ) and 6.7 times higher than that of Rh/CeO 2 (199.9 mol CO mol Rh −1 h −1 ). The incorporation of P induces an elevation of the surface states of Rh species, contributing to lower adsorption capacity for CO, thus leading to the selectivity changes. More importantly, benefiting from the weak acidity and reducibility, AA can assist in the re‐movement of some of the phosphate radicals and the partial reduction of Ce 4+ , thereby providing more oxygen defects for activating CO 2 .