Recent advances in MXenes: a promising 2D material for photocatalysis

Photocatalysis is considered a promising technology for the current environmental crisis and high energy demand caused by industrialization. However, the practical applications and solutions for conventional catalysts are restricted by many limitations, such as poor visible light absorption, wide bandgap, and low surface area of semiconductor photocatalysts. Therefore, developing highly efficient, economical, and noble metal-free catalytic materials containing earth-abundant elements is a hot topic considering photocatalysis for the environmental and energy crises. Two-dimensional (2D) MXenes (transition metal carbides, nitrides, and carbonitrides) are excellent photocatalysts due to their abundant surface groups, interlayer interactions, and adaptable interlayer spacing, and have drawn the most interest in photocatalytic CO2 reduction, hydrogen evolution reactions, photocatalytic degradation reactions, and nitrogen fixation. However, there are still difficulties that prevent their potential application at the moment, with material stability ranking as the biggest one. In this review, we focus on the recent development of the synthesis and properties of MXenes for various environmental and energy demands. The current challenges and the future possible directions to develop and enhance the catalytic performance of MXene catalysts are explained.