Fabrication of a novel Co/Ni-MOFs@BiOI composite with boosting photocatalytic degradation of methylene blue under visible light

In this work, cobalt/nickel-based metal-organic frameworks (Co/Ni-MOFs) modified bismuth oxyiodine (BiOI) composite (Co/[email protected]) was successfully prepared via a hydrothermal method and used as a novel light-driven photocatalyst for the degradation of cationic methylene blue (MB) in aqueous solutions under visible-light irradiation. It was found that Co/Ni-MOFs in combination with BiOI greatly improved the capability of absorbing visible light, resulting in boosting photocatalytic degradation of MB in aqueous solutions without any chemical additives. The photocatalytic activity of Co/[email protected] composites toward MB was enhanced significantly, almost 4 times higher than that of Co/Ni-MOFs, which could be attributed to the reduction of electron-hole pair recombination as well as synergetic effect. Moreover, the results of parallel experiments showed that Co/[email protected] composites could be used as a highly efficient photocatalyst to decompose other dyes including crystal violet (CV), rhodamine 6G (R6G), malachite green (MG), congo red (CR) and methyl orange (MO) under the visible light illumination. The trapping experimental results showed that superoxide radicals (·O2−) was the primary reactive species in the photodegradation reaction of MB, and a possible photodegradation mechanism of MB in the presence of Co/[email protected] was proposed.