One-pot synthesis of m-Bi2O4/Bi2O4−x/BiOCl with enhanced photocatalytic activity for BPA and CIP under visible-light

Abstract

Developing efficient photocatalysts is critical for degradation of organic pollutants. Herein, a highly efficient heterojunction photocatalyst (m-Bi2O4/Bi2O4−x/BiOCl) was synthesized by a hydrothermal method. Through changing the added volume of concentrated HCl acid, the ternary composite based on BiOCl nanosheets matrix on which the m-Bi2O4 micro-rods and the Bi2O4−x nanospheres are firmly attached. The prepared m-Bi2O4/Bi2O4−x/BiOCl showed a favorable degradation rate and mineralization ability towards Bisphenol A (BPA) and Ciprofloxacin (CIP) under visible light irradiation, which degraded 98.3% of BPA in 30 min, 82.3% of CIP in 80 min, and the rate constants were around 30.16 and 2.82 times higher than that of pure BiOCl, respectively. This enhanced photocatalytic activity of m-Bi2O4/Bi2O4−x/BiOCl composite can be originated from the improved light adsorption range and the synergistic effect of type-II and the Z-scheme charge transfer on the interfaces of m-Bi2O4, Bi2O4−x and BiOCl, which then lead to an accelerated separation and migration of photo-generated carriers. Meanwhile, the photoluminescence (PL) test and photoelectrochemistry (PEC) test provided strong evidence for the construction of the heterojunction. Moreover, the repeatability of m-Bi2O4/Bi2O4−x/BiOCl heterojunction photocatalyst was also investigated, and it still remained 90% photocatalytic activity after four successive cycles. This work proposed a possible photocatalytic pathway for m-Bi2O4/Bi2O4−x/BiOCl, which would open up a new avenue for water environment treatment utilizing ternary photocatalysts.