Efficient and stable Nb2O5 modified g-C3N4 photocatalyst for removal of antibiotic pollutant

The removal of pollutant using photocatalysis technology has received much attention due to the increasing serious environmental contamination. In this study, novel Nb2O5/g-C3N4 heterojunctions were fabricated via a facile one-step heating strategy for the first time. Compared to pure g-C3N4 and Nb2O5, the as-prepared Nb2O5/g-C3N4 samples exhibited remarkably enhancing photocatalytic activity for degradation of tetracycline hydrochloride (TC-HCl) both under visible and simulated solar light irradiation. It was found that the 3% Nb2O5 content of heterojunction (3%NO/CN) showed the highest photocatalytic efficiency for TC-HCl degradation, which is about 2.9-fold and 2.4-fold higher than that of pristine g-C3N4 under visible and simulated solar light irradiation, respectively. In addition, the 3%NO/CN sample not only displayed excellent photocatalytic recyclability, but also can efficiently remove TC-HCl even under strong acidic condition (pH = 1). Moreover, the 3%NO/CN heterojunction also exhibited dramatically enhancement of photocatalytic activity for degradation of other fluoroquinolones antibiotic, such as ciprofloxacin (CIP) and levofloxacin (LEV). The highly enhancing photoactivity was attributed to the formation of a heterojunction between g-C3N4 and Nb2O5, which could greatly suppresses the photogenerated electron–hole pair's recombination. The active species trapping and ESR experiments indicated that superoxide radicals and holes are the major active species in which contributing to the photocatalytic process. This work will bring about potential application in treatment of antibiotic pollutant and solar energy conversion.