g-C3N4/Nb2O5 heterostructures tailored by sonochemical synthesis: Enhanced photocatalytic performance in oxidation of emerging pollutants driven by visible radiation

In this study, g-C3N4/Nb2O5 heterostructures were successfully prepared by a sonochemical method based on surface charge-induced heteroaggregation. Under visible irradiation, the heterostructured g-C3N4/Nb2O5 samples exhibited higher activity in the photooxidation of the drug amiloride (AML) and rhodamine B dye (RhB), compared to the pure g-C3N4 and Nb2O5 phases. The enhanced photocatalytic activity of the heterostructures could be attributed to the effective formation of heterojunctions between the g-C3N4 and Nb2O5 semiconductors, causing the migration of photogenerated electrons and holes, hence increasing their lifetimes. Formation of the type-II heterostructure was confirmed by time-resolved photoluminescence, in which the 3CN:1Nb heterostructure showed the longest electron/hole pair lifetime. The 3CN:1Nb and 1CN:3Nb heterostructures exhibited high stability even after four cycles of reuse in RhB dye and drug AML oxidation, respectively. In summary, the combination of g-C3N4 with Nb2O5 to produce a type-II heterostructure is a good strategy to overcome important challenges in photocatalysis.