Direct conversion mechanism from BiOCl nanosheets to BiOF, Bi7F11O5 and BiF3 in the presence of a fluorine resource

Abstract

In this work, we report the facile conversion from BiOCl nanosheets to BiOF, Bi₇F₁₁O₅ and BiF₃ by a novel ion exchange approach, in which the effects of fluorine source, F/Bi molar ratio and reaction medium (ethanol/water) on the products are mainly investigated. A plausible conversion mechanism is proposed to illustrate the formation of BiOF, Bi₇F₁₁O₅ and BiF₃. Furthermore, the photocatalytic activities of the samples are also investigated. It is amazing that under ultraviolet light irradiation (λ ≤ 420 nm), the activity of the as-formed Bi₇F₁₁O₅/BiOCl sample is 3.28 times higher than that of BiOCl for the degradation of methyl orange (MO). It is demonstrated that the improved activity is mainly attributed to the formation of Bi₇F₁₁O₅/BiOCl heterojunction, which has significantly improved the separation and transfer efficiency of charges. It is important that this study provides an initiative post-synthesis strategy to develop new, efficient photocatalysts.