Plasmon-enhanced CO2 electroreduction on copper, silver, and copper-silver nano-catalysts

CO2 electrochemical reduction (CO2ER) allows the conversion of CO2 into fuels and chemicals. Copper is the only known catalyst that converts CO2 into hydrocarbon products but is hindered poor selectivity and stability. Cu-based bimetallic particles have shown to improve the selectivity and stability of the catalysts. This work reports a novel study in the use of a broad-range light source to induce the plasmonic effect in Cu, Ag and Cu-Ag bimetallic nanoparticle catalysts for CO2ER. Active Cu100-xAgx (x = 0, 50, 60, 75, 85, 100 at.%) catalysts were synthesized using a facile chemical reduction and compared to commercial counterparts. The catalytic activity of the particles was correlated with detailed physicochemical characterizations. The synthesized particles were found to be active catalysts for CO2ER, with improved electro-catalytic activities exhibited by Cu85Ag15, Cu60Ag40 and Cu syntheses in respective order. All nanoparticles demonstrated increases in the catalytic activity ranging between 15 and 26 % under white light illumination, attributed to plasmonic promotion using a broad visible wavelength range cold halogen lamp for the first time on CO2ER. The best plasmonic promotion of 26 % was observed in the CuAg commercial alloy. Meanwhile, the best promotion of the synthesized bimetallic particles was of 18 % found in the Cu60Ag40 catalyst. Additionally, improved electrochemical and plasmonic stability was observed with the use of the Cu-Ag bimetallic synthesized structures compared to monometallic Cu.