Enhanced hydrogen peroxide production and organic substrates degradation using atomically dispersed antimony P-doped carbon nitride photocatalysts

In this work atomically dispersed antimony P-doped carbon nitride was prepared with the aim of producing hydrogen peroxide under visible light irradiation and of obtaining organic contaminants degradation. The conjugation of the P-doping can induce significant increase in visible light harvesting, narrowing of band gap energy and shift of the upper edge of the VB to less positive value and the introduction of Sb can efficiently trap oxygen molecules in the Sb-OO end-on structure and at the same time accumulate electrons which act as the photoreduction sites for O-2 via a 2e(-) ORR pathway. Pristine C3N4 and P-doped C3N4 were prepared as references using melamine and ammonium dihydrogen phosphate as precursors and different amount of Sb were added (x = 0.5, 1, 3, 5 mmol) to synthetize Sbx P-doped C3N4. All materials were characterized with multiple techniques, tested for the hydrogen peroxide production and for the degradation of carbamazepine. The pristine C3N4 led to a H2O2 poor production but with the introduced modifications the yield increased and an upward trend during the time was observed. The optimum amount of Sb was found to be 1 mmol and it led to the production of more than 7 times the amount produced by pristine carbon nitride. The degradation of carbamazepine using only visible radiation required prolonged timescales but when we expand the light spectrum to include near-UV, the abatement of the pollutant is achieved in a few hours. The efficiency of the synthesized materials in hydrogen peroxide production suggests possible future developments that take advantage of the excellent peroxide production of atomically dispersed antimony P-doped carbon nitride photocatalysts in Fenton-like processes or involve the use of peroxidase enzymes to achieve enhanced degradative performances.