Three hydroxyl functionalized crystalline K-doped g-C₃N₄ were designed and synthesized, which exhibited high photocatalytic activity for production H₂O₂ directly from natural seawater. Under optimized conditions, the highest H₂O₂ production rate of 1622 μmol g⁻¹ h⁻¹ for duration of 10 h was obtained.

Three hydroxyl functionalized crystalline K-doped g-C₃N₄ were synthesized from dicyandiamide, melamine, ammonium chloride, ammonium oxalate, and ammonium citrate via ionothermal polycondensation using KCl as molten salt under N₂ atmosphere, which served as efficient recyclable photocatalysis realized that generating H₂O₂ directly from seawater with air by 2e⁻ ORR pathway under stimulated solar irradiation in ambient conditions. Under optimized conditions, the highest H₂O₂ production rate of 1622 μmol g⁻¹ h⁻¹ for duration of 10 h was obtained. The cycling performances of HPCN-2 displayed reusable for five times without noticeably loss of its catalytic activity. This work presents a real safer, sustainable, and economical approach for production of H₂O₂ directly from abundant natural seawater.

The proposed mechanism on the ODN and ODS.

In this work, the effect of different parameters on catalyst efficiency in the catalytic oxidative desulfurization (ODS) and denitrogenation (ODN) process is studied. A series of samples with different metal compounds, including Ni, Cu, Co, CoNi, CoCu, and CuNi on a reduced graphene oxide (GO) were prepared by an impregnation method. The synthesized samples were carefully characterized by Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, and X-ray powder diffraction (XRD) techniques. The potential of this methodology was illustrated by the oxidation of 84.11% carbazole (CBZ) and 88.36% dibenzothiophene (DBT) in model fuel containing 500 ppmw sulfur and nitrogen. The effect of DBT and CBZ initial concentration and oxidant type on the oxidation process was investigated. The initial concentration of 250 ppmw for DBT and 100 ppmw for CBZ showed more efficiency than other initial concentrations (1,000, 750, 500, 250 ppmw) for DBT and (500, 400, 250, 100 ppmw) for CBZ, and NaClO as an oxidant showed higher performance than H₂O₂, formic acid, and oxygen. The results indicated that the Co-Cu/rGO catalyst shows higher activity than other prepared catalysts in the oxidation of DBT and CBZ. Moreover, the catalyst could be regenerated three times with no discernible decrease in its catalytic activity. Lastly, the catalytic oxidation of CBZ and DBT was the proposed reaction mechanism.