TiO2-based heterojunctions for photocatalytic hydrogen evolution reaction

Solar-driven photocatalysis hydrogen evolution is a promising method to generate hydrogen from water, a green and clean energy source, using solar and semiconductors. Up to now, TiO2 still represents the most inexpensive and widely studied metal oxide semiconductors for photocatalysis. TiO2 coupling with other semiconductors to form heterojunctions is considered an efficient way to improve photocatalytic performances. In this review, TiO2-based heterojunctions are classified into conventional, p-n type, Z-scheme, S-scheme, and other heterojunctions based on their band structures. The photocatalytic mechanisms of various types of heterojunctions are described in detail. In order to rationally design and better synthesize heterojunctions with excellent performance, the contribution of theoretical calculations to the field of TiO2-based heterojunction photocatalysts and the key role of theoretical prediction are also discussed. Finally, the opportunities and current challenges to promote photocatalytic performance are provided to assist the design of TiO2-based heterojunction photocatalysts with superior performance.