A 2D O-doped g-C₃N₄ photocatalyst was synthesized via a H₂O₂-assisted hydrothermal method. The O-g-C₃N₄ exhibited 87.7% degradation of tetracycline within 60 minutes, along with an excellent hydrogen production rate of 613.67 μmol h⁻¹ g⁻¹.

Herein, a WO3@TCN photocatalyst was successfully synthesized using a self-assembly method, which demonstrated effectiveness in degrading organic dyestuffs and photocatalytic evolution of H2. The synergistic effect between WO3 and TCN, along with the porous structure of TCN, facilitated the formation of a heterojunction that promoted the absorption of visible light, accelerated the interfacial charge transfer, and inhibited the recombination of photogenerated electron–hole pairs. This led to excellent photocatalytic performance of 3%WO3@TCN in degrading TC and catalyzing H2 evolution from water splitting under visible-light irradiation. After modulation, the optimal 3%WO3@TCN exhibited a maximal degradation rate constant that was twofold higher than that of TCN alone and showed continuous H2 generation in the photocatalytic hydrogen evolution. Mechanistic studies revealed that •O2− constituted the major active species for the photocatalytic degradation of tetracycline. Experimental and DFT results verified the electronic transmission direction of WO3@TCN heterojunction. Overall, this study facilitates the structural design of green TCN-based heterojunction photocatalysts and expands the application of TCN in the diverse photocatalytic processes. Additionally, this study offers valuable insights into strategically employing acid regulation modulation to enhance the performance of carbon nitride-based photocatalysts by altering the topography of WO3@TCN composite material dramatically.