Metal-doped carbon nitride: an all-in-one photocatalyst

Abstract

As a typical photocatalyst, graphitic carbon nitride (CN) has received significant attention in the field of energy conversion. Its excellent performance is mainly due to its good chemical stability, low cost, and unique framework structure. However, it is still facing some problems demanding prompt solutions, such as insufficient light absorption, rapid recombination of charge carriers, and absence of reactive sites, which lead to an unsatisfactory photocatalytic performance. Therefore, great efforts have been made to solve these issues. Metal doping is treated as a common strategy to prepare modified CN. A large number of studies have shown that metal-doped CN exhibits an improved photocatalytic performance. It not only promotes charge separation but also incorporates reactive sites and raises the reactive selectivity. As a consequence, metal-doped CN can be considered an all-in-one photocatalyst because it combines the photocatalyst and cocatalyst in one unit. This greatly enhances the charge separation efficiency and utilization, resulting in a high photocatalytic performance. Here, the recent progress of metal-doped CN photocatalysts is summarized according to the location of the metal element in the periodic table. The structure–activity relationship of metal atoms on CN is discussed for photocatalytic H₂ production, H₂O₂ production, CO₂ reduction, and other fields. Dual-atom doped CN turns out to be a more active field due to it providing more active sites to alter catalytic pathways and break the linear relationship. Finally, the intrinsic properties of catalysts e.g. stability and toxicity are summarized in this review.