Improved performance of photosynthetic H2O2 and photodegradation by K-, P-, O-, and S-co-doped g-C3N4 with enhanced charge transfer ability under visible light.

[Display omitted] • K, P, O and S were innovatively simultaneously doped into g-C 3 N 4. • K, P, O, S-g-C 3 N 4 has 12.85 times higher yield of H 2 O 2 than g-C 3 N 4. • The degradation rate of TC by K, P, O, S-g-C 3 N 4 was 1.5 times higher than the pure. • Four elements doping can promote the charge transfer in g-C 3 N 4. • Negatively charged S introduced into the g-C 3 N 4 can facilitate the ·O 2 − production. Elemental doping can modulate the electronic and molecular structure of g-C 3 N 4 to improve its photocatalytic properties. In this study, potassium (K), phosphorus (P), oxygen (O), and sulfur (S) were doped into the g-C 3 N 4 photocatalyst (K, P, O, S/g-C 3 N 4), and the four-element doped photocatalyst was successfully prepared. UV–vis diffuse reflection spectroscopy, photoluminescence, and transient photocurrent revealed that the co-doping of g-C 3 N 4 with K, P, O and S broadens the visible response and accelerates the transfer of photogenerated charges. Under visible light irradiation, the H 2 O 2 concentration produced with K, P, O, S/g-C 3 N 4 was 12.85 times higher than that with g-C 3 N 4. Moreover, tetracycline (TC) can be effectively degraded by the photocatalyst in surface water. The degradation pathway of TC and the molecular structures of 12 intermediates were analyzed by liquid chromatography-mass spectrometry. The superoxide radical (·O 2 −) trapping-electron spin resonance (ESR) technique confirmed that ·O 2 − is the main active species in the system. Therefore, the four-element doping strategy adopted in this research proved the feasibility of increasing the amount of H 2 O 2 produced and degrading the antibiotics in natural water under visible light. [ABSTRACT FROM AUTHOR]