Facile synthesis of nanometer-sized NH2-MIL-101(Fe) decorated BiOBr hybrids for efficient Cr(VI) photoreduction

Abstract

Using a simple oil bath approach, a nanometer-sized NH2-MIL-101(Fe) (NMF) adorned BiOBr heterojunction photocatalyst was effectively created. Compared with the traditional solvothermal method, the synthesis time is shortened by 10 times. Furthermore, nanometer-sized granular NMF particles are uniformly dispersed on BiOBr surface to form plenty of NMF/BiOBr heterojunctions due to chemical action of oxygen vacancies and –NH2 groups. As a result, the as-synthesized NMF/BiOBr photocatalysts exhibit the improved Cr(VI) reduction performance. In 60 min, the 3%NMF/BiOBr heterostructure reaches a maximum Cr(VI) photoreduction efficiency of 99 %. In the 3%NMF/BiOBr heterostructure, Cr(VI) photoreduction occurs at an apparent rate constant that is 7.6 times higher than that of pure BiOBr and 5.44 times higher than that of NMF. The microstructures and photoelectrochemical characteristics of NMF/BiOBr heterostructures were analyzed through state-of-the-art characterization methods. The results show that charge separation and transfer are promoted by the development of heterojunction, which is brought about by the chemical interaction between oxygen vacancies and –NH2 groups. Furthermore, the intimate contact bonding provides electron transport pathways, considerably increasing photocatalytic activity.