Tuning Sn-Cu Catalysis for Electrochemical Reduction of CO2 on Partially Reduced Oxides SnOx-CuOx-Modified Cu Electrodes

Copper-based bimetallic catalysts have been recently showing promising performance for the selective electrochemical reduction of CO 2. In this work, we successfully fabricated the partially reduced oxides SnOx, CuOx modified Cu foam electrode (A-Cu/SnO 2) through an electrodeposition-annealing-electroreduction approach. Notably, in comparison with the control electrode (Cu/SnO 2) without undergoing annealing step, A-Cu/SnO 2 exhibits a significant enhancement in terms of CO 2 reduction activity and CO selectivity. By investigating the effect of the amount of the electrodeposited SnO 2, it is found that A-Cu/SnO 2 electrodes present the characteristic Sn-Cu synergistic catalysis with a feature of dominant CO formation (CO faradaic efficiency, 70~75%), the least HCOOH formation (HCOOH faradaic efficiency, <5%) and the remarkable inhibition of hydrogen evolution reaction. In contrast, Cu/SnO 2 electrodes exhibit a SnO 2 coverage-dependent catalysis—a shift from CO selectivity to HCOOH selectivity with the increasing deposited SnO 2 on Cu foam. The different catalytic performance between Cu/SnO 2 and A-Cu/SnO 2 might be attributed to the different content of Cu atoms in SnO 2 layer, which may affect the density of Cu-Sn interface on the surface. Our work provides a facile annealing-electroreduction strategy to modify the surface composition for understanding the metal effect towards CO 2 reduction activity and selectivity for bimetallic Cu-based electrocatalysts. View Full-Tex