Directional Reconstruction to Highly Active Tandem Sites for Superior Acidic CO₂ Electroreduction.

Abstract

Acidic CO₂ electroreduction (CO₂R) to multi-carbon (C₂₊) chemicals advance the carbon neutrality in the manner of high carbon utilization efficiency; however, it suffers from low selectivity. Designing tandem catalysts is the most promising remedy, yet achieving highly active tandem sites remains an immense challenge due to the potentiodynamic structural evolution. Here self-reducing ion (e.g., iodate) mediated reconstruction, which leverages the self-reduction of dissolved iodate ions is presented to harmonize reconstruction rate of the tandem catalyst and directionally optimize tandem sites in operation. Multiple in situ workflow clearly demonstrate that the exploited CuO/AgIO₃ tandem catalysts occur rapid dissolution of iodate ions in AgIO₃ during the CO₂R, resulting in the formation of defective Ag. Subsequently, the preferential self-reduction of dissolved iodate as a reduction inhibitor delays the reconstruction rate of CuO and directs surface reconstruction toward highly active Cu(100). The asymmetric charge distribution of defective Ag facilitates the generation of ^*COOH and enhances local CO availability to further accelerate the C─C coupling step implemented on Cu(100). The directionally reconstructed CuO/AgIO₃ achieves outstanding C₂₊ Faradaic efficiency of 82% at 1.2 A cm^-2 and a peak j_C2+ (1024 mA cm^-2) is ≈1.5 times higher than that reported in literature benchmark in strong acid electrolyte.