Recent progress in ultrathin two-dimensional semiconductors for photocatalysis

Benefiting from the unique electronic structures and high specific surface areas, two-dimensional (2D) semiconductors present significant advantages in photocatalytic researches for realizing efficient solar energy utilization. As compared with the bulk counterparts, 2D semiconductors tend to possess distinct photoexcitation processes and thus diverse photocatalytic behaviors, owing to the abundant surface structural factors and strong quantum confinement effects. Accordingly, enormous efforts have been devoted to exploring the relationship between the structure and photoexcitation processes in 2D semiconductors, for the sake of the optimization of photocatalytic performance. The attempts not only establish various new 2D semiconductor-based photocatalysts, but also provide in-depth understanding on the involved relevant mechanisms. Herein, an overview of recent advances in the exploitation of 2D semiconductors in photocatalytic applications is presented. By summarizing the investigations on structural characterization and photoexcitation processes, we highlight the relationship between structural factors and photocatalytic performance; in particular, the impacts of excitonic effects mediated by Coulomb interactions on photocatalytic behaviors are discussed. We conclude the review by exploring the future challenges and opportunities for the developments of 2D materials on photocatalytic areas.