Energy Band Engineering Guided Design of Bidirectional Catalyst for Reversible Li-CO 2 Batteries.

Li-CO 2 batteries have aroused 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 has been paid to it. In this work, using Co 3 S 4 as a model system, density functional theory 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 to 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. This article is protected by copyright. All rights reserved.