Synthesis of novel Type-II MnNb2O6/g-C3N4 Mott-Schottky heterojunction photocatalyst: Excellent photocatalytic performance and degradation mechanism of fluoroquinolone-based antibiotics

Fluoroquinolone antibiotics have been encountered in aquatic environments in quantities giving rise to significant concern recently. To cope with this problem, it is necessary to design a semiconductor photocatalyst having excellent photocatalytic efficiency to eliminate the antibiotics. The heterojunction is a likely situate where the efficiency of relevant photocatalyst can be strengthened. In this study, the performance of MnNb2O6/g-C3N4 (MNO/g-CN) composites in the photocatalytic degradation of ciprofloxacin (CIP) and tetracycline-HCl (TCH) antibiotics was explored. Enhanced photocatalytic activity of MNO/g-CN was found to be owing to electron's shifting between the MNO, and g-CN sheets, which promotes the formation of photo-generated e(-)/h(+) pairs. This shows a low-waste, high-performance material exists to eradicate CIP and TCH from wastewater. Further, the structural, photochemical and light interacted properties of the MNO/g-CN photocatalyst, prepared by solvothermal method and sonication, were described using photochemical, physiochemical and electrochemical approaches. The synthesized photocatalyst owes its particular efficiency to its methodical photo-degradation of CIP and TC using visible light. The optimum composite 15% MNO/g-CN evinced the greatest photocatalytic efficiency with CIP and TCH photo-degradation of 94.10%, and 98.50%, respectively, and degradation mechanism were investigated using LC-MS spectroscopy. The suitable photocatalytic activity is ascribed to lower the recombination's rate of e(-)/h(+) pairs. The scavenging evaluations proved that the h(+) and O-center dot(2)- were two major photoactive species accomplishing the CIP and TCH photodegradation over MNO/g-CN under visible region. Our findings pave the way for the construction of efficient binary photocatalysts for antibiotic restitution.

Automated summary

In order to address the presence of fluoroquinolone antibiotics in aquatic environments, it is necessary to design a semiconductor photocatalyst with excellent photocatalytic efficiency. This study explored the performance of MnNb2O6/g-C3N4 composites in the photocatalytic degradation of ciprofloxacin and tetracycline-HCl antibiotics. The enhanced photocatalytic activity of MNO/g-CN was found to be due to the electron's shifting between the MNO and g-CN sheets, promoting the formation of photo-generated e(-)/h(+) pairs, indicating the existence of a low-waste, high-performance material for eradicating ciprofloxacin and tetracycline-HCl from wastewater.