Construction of an all-solid-state Z-scheme photocatalyst based on graphite carbon nitride and its enhancement to catalytic activity

Photocatalysis is a promising technology that can contribute to energy conversion and environmental remediation. Nowadays, the major focus in photocatalysis is the fabrication and development of photocatalytic materials. Graphitic carbon nitride (g-C3N4) has attracted intensive attention because of its low cost, facile preparation, high chemical stability, and non-toxicity. However, it is difficult for pristine g-C3N4 to simultaneously have wide absorption range, high stability, efficient charge separation and strong redox ability, which limits its practical applications. In this review, an artificial g-C3N4-based Z-scheme photocatalyst that simulates natural photosynthesis is presented and thoroughly discussed in terms of the design, preparation, and applications. In particular, the all-solid-state g-C3N4-based Z-scheme system, without reversible redox mediators, has been extensively applied in water splitting, CO2 conversion, and pollutant degradation. Typically, metal oxides, metal sulfides, bismuth-based photocatalytic semiconductors and silver-based photocatalytic semiconductors have been explored for the design of Z-scheme systems with g-C3N4 to enhance the photocatalytic activity by widening the light absorption, facilitating the charge separation, promoting the redox ability and prolonging the charge carrier lifetime. The challenges and prospects for the design and application of g-C3N4-based Z-scheme photocatalysts are also proposed.