In-situ preparation of S-scheme BiOI/BiVO4 heterojunctions with enhanced photocatalytic performance

Close interfacial contact between two photocatalysts can effectively separate photoexcited carriers, improving photocatalytic capacity of the photocatalysts. Herein, S-scheme BiOI/BiVO4 composites were successfully synthesized by a two-step synthetic strategy with the existence of 1-ethyl-3-methylimidazolium iodide ([EMIm]I), NH4VO3 and Bi(NO3)3⋅5H2O. [EMIm]I serves as a solvent to provide iodine source for the heterojunctions to produce small lamellar BiOI anchored on BiVO4. Electrochemical and surface photovoltage spectroscopy (SPS) measurements confirm that S-scheme heterojunctions greatly inhibits the recombination of photoinduced carriers. Photocatalytic removal rate constant of rhodamine B (RhB) and tetracycline (TC) by BiOI/BiVO4 composites is significantly enhanced with visible light, the 5% sample exhibits the highest photocatalytic performance, which is 14.7 and 4.1 times of that of the reference BiVO4 for removal of RhB and TC, separately. The 5% sample can effectively treat Chinese Baijiu industrial wastewater obtained from a local brewery, the removal of total organic carbon (TOC) of the wastewater can achieve about 76% after visible light irradiation for 4 h. Cyclic experiments show that the BiOI/BiVO4 heterojunctions exhibit outstanding stability. The fabricated BiOI/BiVO4 heterojunctions with high activity and persistence have potential applications in water purification. This work proffers a significant reference for in-situ fabrication of S-scheme heterojunctions using ionic liquid.