Rational Engineering of 2D Materials as Advanced Catalyst Cathodes for High-Performance Metal-Carbon Dioxide Batteries

Given the unique characteristic of integrating CO2 conversion and renewable energy storage, metal-CO2 batteries (MCBs) are expected to become the next-generation technology to address both environmental and energy crises. As involving complex gas-liquid-solid three-phase interfacial reactions, cathodes of MCBs can significantly affect the overall battery operation, thus attracting much research attention. Compared to conventional materials, 2D materials offer great opportunities for the design and preparation of high-performance catalyst cathodes, especially showing superior bifunctional electrocatalytic capacity for rechargeable MCBs. The inherent high-specific-surface area and diverse structural architectures of 2D materials enable their flexible and rational engineering designs toward kinetically favorable metal-CO2 electrochemistry. Herein this review, the cutting-edge progresses of 2D materials-based catalyst cathodes are presented in MCBs. The reaction mechanisms of various MCBs, including both nonaqueous and aqueous systems, are systematically introduced. Then, the design criteria of catalyst cathodes, and the merits and demerits of 2D materials-based catalyst cathodes are discussed. After that, three representative engineering strategies (i.e., defect control, phase engineering, and heterostructure design) of 2D materials for high-performance MCBs are systematically described. Finally, the current research advances are briefly summarized and the confronting challenges and opportunities for future development of advanced MCB cathodes are proposed.