MXenes as co-catalysts for the solar-driven photocatalytic reduction of CO2

To mimic natural photosynthesis, semiconductor materials enable the photocatalysis of carbon dioxide (CO2) into valuable solar fuels with the aid of visible-light, which is significant for addressing environment and energy crises. MXenes as co-catalysts with high conductivity, abundant active sites and large specific surface area, are prominent candidates for promoting the photocatalytic reduction of CO2. This review highlights the importance of MXenes as co-catalysts for the photocatalytic reduction of CO2, and consists of four sections: three preparations of MXenes and their basic properties, a description of the fundamental mechanism for the photocatalytic reduction of CO2, and emphasis on the latest cutting-edge research concerning the design considerations and modification strategies, including nitrides, metal oxides, metal salts, perovskite materials, metal-organic frameworks, and functionalized MXenes. The review also illustrates the density functional theory (DFT) research on MXenes, and MXenes combined with semiconductors and single atoms, which highlight the significance of structural defects and dopants in the crystalline structure. The available strategies, such as modification methods, theoretical calculations, controllable selectivity and reproducibility, are presented for further development. This review provides perspectives and challenges of MXenes as co-catalysts for the photocatalytic reduction.