Promoting CuO/Cu(OH)2 for electrocatalytic reduction of CO2 to HCOOH: The study on pyridine-modified surface active sites

Copper-based catalysts have been extensively investigated for electrocatalytic reduction of CO 2 owing to their unique capabilities. To our notice, organic molecules can be employed as molecular modifiers to tailor the CO 2 reduction selectivity of Cu-based catalysts. Herein, three kinds of molecular modifiers, pyridine, triethylamine, and potassium hydroxide have been utilized for fabricating Cu-based electrocatalysts. Experimental investigations reveal that pyridine as molecular modifiers have the ability to alter the surface active sites of the Cu-based catalysts. The modification can facilitate the conversion of CO 2 into HCOOH. Notably, the highest Faradaic efficiency achieved in our tests for HCOOH can reach to an impressive value of 80.2 %. Moreover, the catalyst maintains its structure and performance with high stability that exceeding 10 h at a current density of 30 mA cm −2 (-1.1 V vs. RHE). Based on structural characterization and theoretical calculations, we propose that the pyridine molecule can facilitate CO 2 accumulation, and the pyridine modification of the CuO/Cu(OH) 2 surface active site can reduce the reaction energy barrier for the electrocatalytic reduction of CO 2 to HCOOH.