Energy Band Engineering Guided Design of Bidirectional Catalyst for Reversible Li–CO2 Batteries

Abstract Li–CO 2 batteries arouse great interest in the context of carbon neutralization, but their practicability is severely hindered by the sluggish CO 2 redox reaction kinetics at the cathode, which brings about formidable challenges such as high overpotential and low Coulombic efficiency. For the complex multi‐electron transfer process, the design of catalysts at the molecular or atomic level and the understanding of the relationship between electron state and performance are essential for the CO 2 redox. However, little attention is paid to it. In this work, using Co 3 S 4 as a model system, density functional theory (DFT) calculations reveal that the adjusted d ‐band and p ‐band centers of Co 3 S 4 with the introduction of Cu and sulfur vacancies are hybridized between CO 2 and Li species, respectively, which is conducive to the adsorption of reactants and the decomposition of Li 2 CO 3 , and the experimental results further verify the effectiveness of energy band engineering. As a result, a highly efficient bidirectional catalyst is produced and shows an ultra‐small voltage gap of 0.73 V and marvelous Coulombic efficiency of 92.6%, surpassing those of previous catalysts under similar conditions. This work presents an effective catalyst design and affords new insight into the high‐performance cathode catalyst materials for Li–CO 2 batteries.