Synergistic promotion photocatalytic H2O2 production over modified g-C3N4 via defect and doping engineering

Potassium dopants and nitrogen defects are simultaneously introduced into graphitic carbon nitride (g-C₃N₄, abbreviated as CN) with a facile one-pot direct calcination strategy. The co-calcination of melamine with KCl and oxamide leads to exciting positive influence, such as reducing the intermolecular aggregation, preventing the excessive crystal growth and tight stacking between layers, extending the interlayer stacking time, and favoring the formation of additional pores. Therefore, the resulting materials deliver superior performance to the pristine CN. Especially, the optimal CPCN, which is fabricated with a molar ratio of 1: 1 for melamine to oxamide, exhibits exceptional photocatalytic behavior in H₂O₂ production, and the concentration of H₂O₂ produced can reach 470.84 μM within 4 h in the presence of CPCN (0.5 mg mL⁻¹) irradiated by visible light, nearly 50 times that of CN. The corresponding H₂O₂ production rate is 1569.45 µmol g^–1 h^–1, significantly higher than the results over CN-based materials reported in literature. Moreover, the concentration and production rate can further separately increase to 1170.37 μM and 3901.22 µmol g^–1 h^–1 irradiated by the simulated sunlight. Also, CPCN depicts superior photocatalytic performance in the degradation of organic pollutants (such as rhodamine B dye and oxytetracycline antibiotic) in water to the control samples. This study not only develops an interesting avenue for the rational design of high-performance CN-based photocatalysts, but also offers some meaningful insights on photocatalytic H₂O₂ production and organic contaminant degradation.