Orienting Z scheme charge transfer in graphitic carbon nitride-based systems for photocatalytic energy and environmental applications

Abstract

In recent years, photocatalysis and photoelectrocatalysis (PEC) have emerged as efficient strategies for facing the energy crisis and environmental pollution. In this regard, the very suitable and exciting material, graphitic carbon nitride (g-C₃N₄), has drawn spectacular attention because of its fascinating physicochemical properties. However, its practical application in the field of photocatalysis and PEC is still a bottleneck due to its narrow solar energy absorption range, low surface area, which provides less active sites, low electronic conductivity due to deficient CN donor density, poor electron–hole separation efficiency, insufficient redox potentials, and difficulty in the formation of thin films due to its poor dissolution in common solvents. To optimize the redox potential and provide effective spatial charge separation, Z scheme systems are being fabricated by imitating the natural photosynthesis process. In this review, the historical development of g-C₃N₄-based Z scheme systems is summarized along with their construction, synthesis, and various photocatalytic and PEC applications. g-C₃N₄-based Z scheme systems, such as the redox mediator solution-phase Z scheme, solid-state Z scheme, and direct Z scheme, and their characterization methods have been discussed briefly. Also, the methodology for the detection of Z scheme charge transfer processes has been explored. Lastly, conclusions and various future perspectives regarding the challenges in the construction and progress of the Z scheme photocatalytic systems are presented.