Self-supported beaded Au@Co3O4 nanowire arrays perform electrocatalytic CO2 reduction in water to syngas and water oxidation to O2

Abstract

Syngas, as a necessary feedstock dependent on non-renewable fossil fuels, is a mixture of CO and H₂, which could be prepared by a renewable strategy via electrochemical CO₂ reduction in water electrolyte solutions. Herein, beaded Au@Co₃O₄ nanowire arrays (denoted as Au@Co₃O₄ NAs) were obtained by immersion in HAuCl₄ solution with Co₃O₄ nanowire arrays. The Au@Co₃O₄ NAs exhibited outstanding electrochemical performance of producing syngas via tuning from 1 : 1 to 4 : 1 with controlling voltage. In addition, the Au@Co₃O₄ NAs showed better catalytic performance for the oxygen evolution reaction with an overpotential of 320 mV at a current density of 50 mA cm⁻², along with a small Tafel slope of 75 mV dec⁻¹ in 1 M KOH solution. The electrochemical performance of Au@Co₃O₄ NAs is obviously superior to Co₃O₄ NAs, which will open up a viable strategy for the design and fabrication of a bi-functional electrocatalyst for the overall reaction (CO₂ + H₂O → CO + H₂ + O₂).