DEVELOPMENT OF ALKALINE-EARTH ELEMENT-MODIFIED GRAPHITIC CARBON NITRIDE PHOTOCATALYST FOR COMPLETE ELIMINATION OF PHARMACEUTICAL POLLUTANT UNDER VISIBLE-LIGHT IRRADIATION

Abstract

A novel photocatalyst, Ba-doped graphitic carbon nitride (g-C3N4), was synthesized via a facial thermal condensation method. Ba at a loading of 2% revealed the highest photocatalytic degradation efficiency of tetracycline (TC) (91.94%) after 120 min of visible light irradiation at an optimal pH of 10. An overall synergy of 69.26% was observed in the case of Ba (2%)-doped g-C3N4 over pure g-C3N4. The remarkable improvement in the TC degradation performance is due to the narrower band-gap energy, the larger surface areas and the lower recombination rate of charge carriers detected through photoluminescence (PL) quenching, suggesting the multiple roles of the Ba doping. The synthesized novel photocatalyst displayed extremely high stability after 5 cycles as confirmed through various characterization techniques. The intermediates generated during the photocatalytic reaction were also detected through liquid chromatography–mass spectrometry (LC-MS) analysis and used to predict the degradation pathway of TC. Photoelectrochemical (PEC) measurements combined with photocatalytic performance obviously demonstrated that Ba doping effectively enhanced the separation of charge carriers and decreased the electron/hole recombination in the g-C3N4 structure.