For decades, global warming and energy shortages have been two urgent problems in human society. The solar-driven photocatalytic conversion of carbon dioxide (CO₂) into hydrocarbon fuels is expected to become a technology to solve these problems. Two-dimensional (2D) materials shine in the field of photocatalytic CO₂ due to their layered structure, larger specific surface area, more active sites, and larger charge transfer efficiency. This article reviews the progress of CO₂ reduction by several types of 2D materials in recent years. Generally, the reduction of CO₂ is difficult in terms of kinetics and thermodynamics, but it is found through theoretical calculations and experiments that 2D materials have certain advantages in the reduction of CO₂. Then the preparation methods of 2D materials are summarized and a variety of 2D materials are discussed and classified. Finally, an outlook on the development trend of 2D materials is made. This review aims to provide systematic and concise guidance for the design of 2D nanomaterials for photocatalytic CO₂ reduction.

The effective separation and migration of photogenerated charge carriers in bulk and on the surface of photocatalysts will significantly promote photocatalytic efficiency. However, the synchronous regulation of photocharges on both counts is challenging. Herein, the simultaneous separation of bulk and surface photocharges is conducted to enhance photocatalytic activity by coupling the surface defects and lattice engineering of bismuth oxybromide. The depth-modulated Bi₅O₇Br ultrathin nanosheets with an abundance of bismuth in the crystal structure increased the internal electric field, which propelled the separation and migration of photocharges from bulk to the surface. Creation of oxygen vacancies (OVs) on the nanosheet surface forms local electric fields, which can stimulate the migration of charges to active sites on the catalyst surface. Therefore, the OV-assembled Bi₅O₇Br nanosheets demonstrated enhanced photocatalytic degradation efficiency under simulated solar-light illumination. This study proved the possibility of charge governing via electric field modulation based on an integrated strategy.