Recent Advances in Diverse MXenes-Based Structures for Photocatalytic CO₂ Reduction into Renewable Hydrocarbon Fuels

Photocatalytic CO2 reduction into renewable hydrocarbon fuels is a green solution to address CO2 emission and energy issues simultaneously. However, the fast recombination of photogenerated charge carriers and the sluggish surface reaction kinetics restrict the efficiency of photocatalytic CO2 reduction. The emergence of 2D MXenes has potential in improving the efficiency of photocatalytic CO2 reduction, owing to their high electrical conductivity, flexible structural properties, and abundant active sites. Hence, this review will concisely summarize and highlight recent advances of MXenes-based photocatalysts used in photocatalytic CO2 reduction. First, the synthesis and properties of MXenes is briefly introduced. Second, the mechanism of CO2 photoreduction along with the roles of MXenes in photocatalytic CO2 reduction are summarized, including promoting the adsorption of CO2, enhancing the separation of photo-induced charge carriers, acting as a robust support, and photothermal effect. Third, different kinds of MXenes-based photocatalysts such as MXenes/metal oxides, MXenes/nitrides, MXenes/LDH, MXenes/perovskite, and MXene-derived photocatalysts for CO2 reduction are classified via the type of semiconductors. Finally, the challenges and perspectives are also presented, including exploring suitable MXenes via machine learning, uncovering the structure-activity relationship by in situ, time- and space-resolved characterization techniques, improving anti-oxidization ability, and scale-up applications.