Synergistic Cs/P Co-doping in Tubular g-C3N4 for Enhanced Photocatalytic Hydrogen Evolution

Developing high-performance photocatalysts for solar hydrogen production requires the synergistic modulation of chemical composition, nanostructure, and charge carrier transport pathways. Herein, we report a Cs and P co-doped tubular graphitic carbon nitride (Cs/PTCN-x) photocatalyst synthesized via a strategy that integrates elemental doping with morphological engineering. Structural characterizations reveal that phosphorus atoms substitute lattice carbon to form P-N bonds, while Cs+ ions intercalate between g-C3N4 layers, collectively modulating surface electronic states and enhancing charge transport. Under visible-light irradiation (λ ≥ 420 nm), the optimized Cs/PTCN-3 catalyst achieves an impressive hydrogen evolution rate of 8.085 mmol·g-1·h-1—over 33 times higher than that of pristine g-C3N4. This remarkable performance is attributed to the multidimensional synergy between band structure tailoring and hierarchical porous tubular architecture, which together enhance light absorption, charge separation, and surface reaction kinetics. This work offers a versatile approach for the rational design of g-C3N4-based photocatalysts toward efficient solar-to-hydrogen energy conversion.