Promoting carbon dioxide electroreduction toward ethanol through loading Au nanoparticles on hollow Cu2O nanospheres

Electrochemical CO 2 reduction (CO 2 RR) to ethanol is a way to advance CO 2 utilization toward a renewable chemical feedstock and fuel. In present study, an approach to promote ethanol production is employed through adding Au, which is favorable toward CO formation, onto Cu 2 O catalysts. Namely, the Cu 2 O hollow nanospheres with a size of 150−180 nm were synthesized by a soft template method, and then Au nanoparticles of ∼7 nm were loaded to obtain Au x /Cu 2 O composites. The Au x /Cu 2 O catalysts have an earlier onset for ethanol production than Cu 2 O. Besides, Au x /Cu 2 O catalysts display the significantly enhanced Faraday efficiencies (FEs) of CO and ethanol, the suppressed hydrogen evolution reaction and the slightly weakened HCOOH formation. Among them, Au 0.17 /Cu 2 O stands out with the highest FEs of ethanol from 10.8%–16.2% throughout the measuring potentials, suggesting an optimal amount of Au. Furthermore, it is found that the FEs of ethanol increase as the atomic ratio of Au/Cu increases at the medium reduction potentials (-1.1 V to -1.3 V). Besides, it is demonstrated that ethanol formation is more favorable over ethylene formation, evidenced by the ratio of FE ethanol /FE ethylene reaching 2.0, 3.3, 4.1 on three Au x /Cu 2 O catalysts, respectively. This correlation between the ethanol production and the Au amount reflects that Au plays a crucial role in promoting ethanol formation. The enhanced ethanol formation is ascribed to more CO formation on Au sites to promote C–C coupling. Our study demonstrates an effective approach to develop Cu-based electrocatalysts for ethanol formation from CO 2 .