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 CO2 owing to their unique capabilities. To our notice, organic molecules can be employed as molecular modifiers to tailor the CO2 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 Cubased catalysts. The modification can facilitate the conversion of CO2 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 CO2 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 CO2 to HCOOH.