S-scheme heterojunction photocatalysts based on 2D materials

As an emerging photocatalytic system for the use of solar energy, step-scheme (S-scheme) heterojunction has demonstrated its high efficiency and prospect in the realms of energy conversion and environment treatment. To provide a deep understanding of the superiority of the S-scheme heterojunction in photocatalysis, the history and evolution of the S-scheme heterojunction are revisited and covered based on the challenges and issues faced by single photocatalysts and other types of heterojunctions. Afterwards, the design principle and characterization techniques of the S-scheme heterojunction are summarized and reviewed. Owing to the unique structural features with fascinating electronic, photonic, and chemical properties, two-dimensional (2D) materials have been widely used in the construction of the S-scheme heterojunctions. Based on the contact mode of the two components, the S-scheme heterojunction based on the 2D materials can be classified into 0D/2D, 1D/2D and 2D/2D heterojunctions. The versatility of the combinations provides 2D-based heterostructures plenty of intriguing physio-chemical properties, making them promising candidates for the photocatalysis of many critical reactions. Herein, the latest updates for the development of the 2D materials-based S-scheme heterojunctions are presented and discussed. Moreover, the challenges and future directions for the S-scheme heterojunctions are critically approached and outlined.