Porous g-C3N4-encapsulated TiO2 hollow sphere as a high-performance Z-scheme hybrid for solar-induced photocatalytic abatement of environmentally toxic pharmaceuticals

Abstract

Herein, we rationally constructed a hybrid heterostructure comprising porous g-C3N4 (CN)-encapsulated anatase TiO2 hollow spheres (TOHS) via a synthesis method that involves hydrothermal and calcination treatments. The fabricated hybrid, termed CN/TOHS, demonstrated extraordinary activity toward the degradation of environmentally toxic pharmaceutical substances (acetaminophen and ciprofloxacin) in aqueous solutions under simulated sunlight irradiation; the activity of CN/TOHS was superior to that attained for individual TOHS and CN counterparts. In particular, the CN/TOHS hybrid containing 13.3 wt.% of CN on TOHS displayed the optimum degradation activity among the tested catalysts used in this study, and it also possessed exceptional recyclability and stability during consecutive degradation tests. The remarkable photocatalytic activity and stability of the hybrid were predominantly ascribed to the large solid interfacial contact between constituents, TOHS and CN, induced by effective hybrid structure, which boosted the interfacial charge transfer and impeded with the direct recombination of photo-induced charges. Notably, the results of the liquid chromatography–mass spectrometry analysis corroborated the effective mineralization of model pharmaceutical pollutants in the presence of the CN/TOHS hybrid. The simple interfacial engineering strategy presented in this study offers a potential route for the rational design of novel catalysts for application in environmental remediation and solar energy conversion.