Rationally designed Ta3N5/BiOCl S-scheme heterojunction with oxygen vacancies for elimination of tetracycline antibiotic and Cr(VI): Performance, toxicity evaluation and mechanism insight

Abstract

S-scheme heterojunction photocatalysts have been the “stars” in the field of photocatalysis. Herein, a novel S-scheme heterojunction of Ta3N5/BiOCl with oxygen vacancies (OVs) was fabricated via a facile method. The charge separation and transport mechanism of this Ta3N5/BiOCl S-scheme heterojunction was verified by the analyses of band energy structures, active species, photoelectric behaviors and DFT theoretical calculation. Compared with Ta3N5 and BiOCl, the Ta3N5/BiOCl unveils substantially upgraded photocatalytic property under visible light, and the photocatalytic efficiency for removal of tetracycline (TC) and hexavalent chromium (Cr(VI)) reaches 89.6% and 91.6%, respectively. The substantial enhancement of the photocatalytic activity is attributed to the synergistic effect of the S-scheme hetero-structure and oxygen vacancies, which improves the visible-light absorption, while promoting the spatial separation of charge carriers with the optimum redox capacity, thereby boosting the production of active species for catalytic reactions. The TC degradation pathway is deduced and the toxicity evolution of TC is appraised using the QSAR method. In a nutshell, this work gives a deep understanding of the photocatalytic mechanism based on Ta3N5/BiOCl as well as presents a newfangled thought for developing highly efficient S-scheme heterojunction photocatalysts for water decontamination.