Synergistic regulation of g-C3N4 band structure by phosphorus and sodium doping to enhance photocatalytic hydrogen peroxide production efficiency

[Display omitted] •P and Na co-doping narrows the band gap, boosts light absorption, lowers transition energy, and enhances H₂O₂ yield for wastewater treatment.•DFT simulations confirm band gap narrowing and enhanced carrier migration, aligning with experimental results.•The one-step thermal polymerization method enables efficient dual doping, suitable for large-scale industrial photocatalyst production.•Our method enables in-situ H₂O₂ generation for wastewater treatment, reducing infrastructure and handling risks under mild conditions. In addressing the industrial need for a simple, equipment-minimal, and non-toxic method of in-situ hydrogen peroxide (H2O2) production, this paper presents a cost-effective, environmentally friendly photocatalyst. Our design strategy focuses on the dual-element doping of phosphorus and sodium into graphitic carbon nitride (g-C3N4), chosen to synergistically enhance photocatalytic performance. This approach yields a notable H2O2 production concentration of 3001.64 μmol·g−1·L-1 within 100 min, using isopropanol as a sacrificial agent, which was 61-fold increase compared to bulk g-C3N4. Density Functional Theory (DFT) calculations were performed to elucidate the alterations in the band structure of the catalyst induced by dual-element doping, which consequentially engendered an asymmetric intrinsic electric field. Additionally, oxygen’s transition state affinity due to phosphorus doping was also investigated to reveal the mechanisms of synergistic catalysis. This development contributes to meeting industrial demands for pollutant degradation via Fenton processes and presents a sustainable alternative to traditional H2O2 production methods.