Influence of Phosphorus Doping on Triazole-Based g-C3N5 Nanosheets for Enhanced Photoelectrochemical and Photocatalytic Performance

Triazole-based g-C3N5, a potential catalyst, has received little attention over the years. We prepared phosphorus-doped g-C3N5 with one triazole and two triazine units for the first time to investigate its photoelectrochemical (PEC) and photocatalytic properties. The doping states and crystalline structures of the samples were determined using X-ray techniques, namely, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption fine structure analysis. Our results suggested that the phosphorus was substituted into carbon sites form P–N/P═N bonds with four coordination, which contribute P 2p level donor states in the band gap to enhance light absorption and reduce charge separation. Therefore, P-doped g-C3N5 exhibited higher PEC current density and better photocatalytic efficiency toward the degradation of rhodamine B dye or tetracycline under light irradiation compared to the undoped g-C3N5 sample. However, excess phosphorus doping resulted in the formation of impurities and disrupted the triazine and triazole units, reducing the PEC and photocatalytic efficiency. In summary, P-doped g-C3N5 was successfully prepared in the present study and represents a promising, facile, and effective catalyst for energy applications and environmental remediation.