Electronic and geometric structure engineering of bicontinuous porous Ag–Cu nanoarchitectures for realizing selectivity-tunable electrochemical CO2 reduction

Abstract

Abstract The electrochemical conversion of waste carbon dioxide into hydrocarbon fuels represent a promising strategy for clean and sustainable energy production. However, the design of outstanding electrocatalysts that can reduce CO2 in an efficient and selective manner is challenging, and the fundamental understanding on reaction mechanism is still limited. Herein, we report the preparation of self-supported Ag–Cu bimetallic catalysts with bicontinuous nanoporous geometries and adjustable compositions through an electrochemical anodizing/dealloying process of Ag52Cu39Sn9 alloy foil to exploit their performances in electrocatalytic CO2 reduction. By changing the compositions from Ag91Cu9 to Ag65Cu35, the variations in atomic arrangement and electronic structure around the active sites bring synergistic effects on the binding strength of different reaction intermediates, realizing tunable product selectivity from CO to formate at high Faradaic efficiencies. In-situ Raman analysis and density functional theory calculations confirm that as the Ag–Cu atomic ratio shifts, the variations of formation free-energies and desorption capacities of intermediates lead to different reaction pathways and final products. The findings in this study provide a promising route to modulate the atomic structures and improve the properties of electrocatalysts towards CO2 fixation.