Facile fabrication of mesoporous BiOCl/(BiO)2CO3/Bi2O3 ternary flower-like heterostructured microspheres with high visible-light-driven photoactivity

Abstract

A novel anion exchange method followed by a simple solid-state reaction process has been developed for the controllable synthesis of mesoporous BiOCl/(BiO)₂CO₃/Bi₂O₃ ternary flower-like heterostructured microspheres (HMSs) using uniform BiOCl microspheres as templates. Firstly, the transformation of BiOCl microspheres into BiOCl/(BiO)₂CO₃ binary HMSs was achieved through a facile in situ anion exchange reaction in the presence of Na₂CO₃ aqueous solution at 80 °C for 8 h. Secondly, the mesoporous BiOCl/(BiO)₂CO₃/Bi₂O₃ ternary HMSs were obtained by thermal decomposition of the BiOCl/(BiO)₂CO₃ composites at 400 °C for 4 h in air. Importantly, the Bi₂O₃ and (BiO)₂CO₃ content in the ternary system can be conveniently tuned by varying the Na₂CO₃ concentration in the anion exchange reaction process. Benefiting from unique structural features, the as-obtained mesoporous BiOCl/(BiO)₂CO₃/Bi₂O₃ ternary flower-like HMSs exhibit remarkably enhanced photocatalytic activity for the degradation of organic pollutants under visible-light irradiation compared with BiOCl/(BiO)₂CO₃ and Bi₂O₃/(BiO)₂CO₃ binary composites and the mechanical mixture of BiOCl, Bi₂O₃, and (BiO)₂CO₃ (BBB-mixture), and the total organic carbon (TOC) removal rate could reach 67% after irradiation for 60 min. Furthermore, a test for radical scavengers indicated that photogenerated holes (h⁺) and superoxide anion radicals (O₂˙⁻) were the main reactive species in the BiOCl/(BiO)₂CO₃/Bi₂O₃ ternary composites.