Recent advances in the design and application of graphitic carbon nitride-based dual Z-scheme heterojunctions

Dual Z -scheme heterojunctions have emerged as next-generation photocatalysts, offering superior redox capacity, enhanced charge carrier separation, and broader light absorption compared to conventional type-II and single Z -scheme systems. Among these, graphitic carbon nitride (g-C₃N₄)—a visible-light-responsive, metal-free semiconductor—provides a versatile platform for constructing ternary heterostructures with optimized interfacial interactions and enhanced photocatalytic activity. This review uniquely focuses on g-C₃N₄-based dual Z -scheme systems, critically analyzing their rational design, synthesis approaches, and architecture-dependent charge transfer pathways. A comparative evaluation of major synthesis strategies—including in situ precipitation, solvothermal assembly, ultrasonic-assisted calcination, and wet-impregnation–highlights their impact on interfacial contact, charge migration dynamics, and overall performance across diverse applications such as solar-driven energy conversion, environmental remediation, and green chemical synthesis. Existing challenges—including limited interfacial engineering, restricted material combinations, and scale-up barriers—are discussed alongside emerging opportunities, particularly the integration of machine learning for predictive catalyst design. This review provides a forward-looking framework to guide the development of highly efficient g-C₃N₄-based dual Z -scheme heterojunctions for next-generation sustainable technologies.