Electrocatalytic selectivity to H2O2 enabled by two-electron pathway on Cu-deficient Au@Cu2-xS-CNTs electrocatalysts

Abstract

Electrochemical hydrogen peroxide (H2O2) production by two-electron oxygen reduction reaction (ORR) is an efficient and promising method to alternate industrial anthraquinone process. Herein, the Cu-deficient Au@Cu2-xS-CNTs core–shell electrocatalysts were synthesized for two-electron ORR, and composition, surface and structural properties were investigated using physicochemical characterizations. The Cu-defective Au@Cu2-xS-CNTs catalysts exhibit higher catalytic ORR activity and H2O2 specific productivity than Au@Cu2O-CNTs, indicating that the introduction of Cu defects effectively improves the two-electron transfer of ORR. The composition-optimized Au@Cu1.75S-CNTs sample with the abundant Cu defects exhibits high H2O2 selectivity (∼94 %) and good stability. Theoretical calculations reveal that the introduction of Cu defects can significantly lower the reaction energy barrier of the determinant intermediate OOH* formation of two-electron ORR pathway. This endows the synthesized catalysts with improved resistance to H2O generation. Our work deepens the fundamental understanding for guiding the optimization of H2O2 electrosynthesis catalysts to enhance selectivity and efficiency of two-electron pathway.