Metal-organic frameworks (MOFs) for photocatalytic CO2 reduction

The utilization of solar energy for CO2 conversion to produce valuable chemicals or fuels is extremely appealing since it can simultaneously reduce the greenhouse effect and relieve the energy shortage pressure. In addition to the commonly used semiconductor-based photocatalysts, metal-organic frameworks (MOFs), a class of micro-mesoporous hybrid materials, are recently emerging as new types of photoactive materials for CO2 reduction due to their excellent adsorption capability toward CO2 and unique structural characteristics. In this review, we summarized the recent applications of MOFs for photocatalytic CO2 reduction, in which MOFs either act directly as the photocatalysts for CO2 reduction or as components in a hybrid photocatalytic system to promote CO2 reduction. This review starts with a brief introduction of the background of photocatalytic CO2 reduction, followed by a summarization of CO2 reduction catalyzed by photoactive ligands and metal nodes in MOFs, respectively. Thereafter, the construction of hybrid photocatalytic systems in which MOFs play a role in promoting photocatalytic CO2 reduction is described. Finally, the limitations, challenges and future prospects of the application of MOFs to CO2 reduction are addressed. We hope that this review not only can serve as a starting point to get into this largely unexplored field but can also stimulate intensive research on the rational design and development of more creative MOF systems for light induced CO2 conversion, which is a green and sustainable strategy for CO2 utilization.