Transforming Cu into Cu2O/RuAl intermetallic heterojunction for lowering the thermodynamic energy barrier of the CO2 reduction and evolution reactions in Li–CO2 battery

Abstract

The Li–CO2 battery has been under the spotlight of future battery technologies since it can achieve CO2 utilization and energy conversion simultaneously. However, its advancement is hampered by poor energy efficiency and limited reversibility due to the sluggish kinetics of the CO2 reduction and evolution reactions. Herein, a multiscale nanoporous interpenetrating‑phase nanohybrid of RuAl intermetallic and Cu2O (MP-Cu2O/RuAl) was carved by driving synchronous phase and microstructure evolutions through dealloying of one RuCuAl master alloy. The built-in RuAl intermetallic and Cu2O closely stack to form abundant nano-interfaces with revolutionized electronic structure. The theoretical simulations reveal that the Cu2O/RuAl interface can distinctly reduce the energy barrier of the Li2CO3 decomposition reaction. The interconnected pore channels with large surface area can enhance catalytic site accessibility, mass transfer, and uniform deposition of the discharge products. In situ differential electrochemical mass spectrometry discloses that the CO2-to-electron ratio during charging coincides with the theoretical value of 3/4, demonstrating the high efficacy of MP-Cu2O/RuAl in achieving the recycling of CO2. The dealloying protocol provides an affordable platform to empower transition metal oxides into high-efficiency electrocatalysts by hybridizing with metallic nano-sponge for advancing the application of Li–CO2 batteries.