Confining Benzotriazole Around CuAg Alloy With Polyvinylidene Fluoride for Improved Production of C2 Species via CO2 Electroreduction.

Electroreduction of carbon dioxide (CO2ER) to multi-carbon (C2+) products is limited by the poor selectivity of copper catalysts, the only metal able to produce C2+ species. Although alloying and molecular modification have been applied to improve the C2 selectivity during CO2ER, the improvements are still not high enough. Herein, we present a simple bilayer coating strategy to significantly enhance the C2 selectivity on copper-silver (CuAg) alloy surface. By sequentially coating a bilayer of benzotriazole (BTA) and polyvinylidene fluoride (PVDF) on the surface of CuAg alloy, the Faradaic efficiency (FE) toward C2 species increased from 61.4%±2.5% to 78.3%±4.1% in an H-type electrochemical cell. This performance enhancement remained stable during a 10-hour long-term measurement. The PVDF layer could not only modulate the mass transportation of reactants but also confine BTA molecules and prevent their dissolution and/or detachments. The BTA molecules could stabilize key reaction intermediates, working synergistically with the spillover of Ag, to realize a high FE toward C2 during CO2ER. Our finding clarifies the synergistic effects between the sequentially coated small molecule and polymer on alloy catalysts, and this strategy may be combined with many other existing strategies to further improve the FEs of various products during CO2ER in the future.