Single Metal Atom Decorated Carbon Nitride for Efficient Photocatalysis: Synthesis, Structure, and Applications

Graphitic carbon nitride (g-C3N4), as a new type of visible-light-responsive photocatalyst, has a unique 2D building unit, excellent chemical stability, and a tunable electronic structure. At the same time, g-C3N4 has a large number of periodically separated N atoms that can act as anchoring sites for various functional materials, particularly single metal atoms (SMAs). Recently, supported single atoms have attracted much attention in the field of photocatalysis. Also, it has been shown that g-C3N4 is a wonderful material to support atomically dispersed SMA photocatalysts, such as Pd, Pt, Cu, Co, Ni, and Fe. Herein, the latest progress on g-C3N4 synthesis strategies and the synergy between this material and SMA catalysts is summarized. The coordination environment and electronic structure of SMAs on g-C3N4 are discussed, and the available characterization techniques for studying the physiochemical properties are summarized. Applications of g-C3N4-supported SMA catalysts for photocatalytic hydrogen production, CO2 reduction, organic synthesis, and nitrogen fixation are reviewed. This review is concluded with a discussion of the remaining challenges and future perspectives. It is hoped that by using SMAs anchored on g-C3N4 as examples this review will help to elucidate the fundamentals and the great potential of SMA-based catalysts, and promote their further development.