Multiscale structural regulation of Two-Dimensional materials for photocatalytic reduction of CO2

The photocatalytic conversion of carbon dioxide (CO₂) into sustainable fuels and chemicals is a promising method to enhance the natural carbon cycle and combat global warming. This approach involves developing efficient, stable, and cost-effective photocatalysts, with two-dimensional (2D) materials like graphitic carbon nitride (g-C₃N₄) and hydrotalcite standing out owing to their extensive surface areas and superior charge separation and transfer capabilities. The thinness of these materials shortens carrier transport paths, improves CO₂ and water adsorption and activation, lowers energy barriers, and selectively enhances specific reactions. However, focusing solely on thickness might oversimplify the issue, as morphology, edge structures, active site exposure, and interfacial effects also play crucial roles in photocatalytic performance. Adjusting electronic structures through nanoscale parameters like thickness is vital, but a comprehensive consideration of these complex interactions is essential. While previous studies have examined the performance and optimization of 2D materials, in-depth analyses of thickness and structure–activity relationships are lacking, which hinders advanced catalyst design. This review discusses the structural characteristics of various 2D nanomaterials, their role in promoting electron-hole pair separation, rapid electron migration, and effective CO₂ adsorption, and also evaluates future prospects of these materials in fuel utilizations and the challenges.