This book systematically explores carbon nitride-based semiconductors for photocatalytic hydrogen production through water splitting. Beginning with fundamental concepts of hydrogen generation, it details modifications to pure g-C3N4 and interfacial engineering designs before examining various composite materials: CeO2/g-C3N4 nanocomposites demonstrate enhanced charge separation, while CoO nanoparticle integration improves visible-light absorption. The text analyzes N-doped ZnO/g-C3N4 heterojunctions, MnO2-loaded architectures for oxidative stability, and oxygen-deficient LaVO4/g-C3N4 systems. Advanced configurations include Co-C3N4/BiPO4 dual-cocatalysts, atomically dispersed Co-N4 sites in 2D frameworks, and B/P-doped variants for bandgap modulation, concluding with molten-salt synthesized Fe@C3N4 nanosheets. Each system's synthesis, characterization, mechanistic pathways, and hydrogen evolution performance are rigorously evaluated, culminating in forward-looking perspectives for nex
