Solar-Driven Fixation of Bismuth Oxyhalides on Reduced Graphene Oxide for Efficient Sunlight-Responsive Immobilized Photocatalytic Systems

Developing green, cheap technology for large-scale production of photocatalysts in colloidal dispersion form enables the fabrication of efficient sunlight-responsive immobilized photocatalytic systems to address current environmental issues. It is reported for the first time, a cost-effective, energy-efficient, green, single-step approach for solar-driven fixation of bismuth oxybromideiodied solid solution (BiOBr_0.75 I_0.25 SS) on reduced graphene oxide (rGO) sheets by solar light irradiation of BiOBr_0.75I_0.25-graphene oxide (GO) dispersion in ethanol medium. Upon solar irradiation, GO is photocatalytically reduced by BiOBr_0.75I_0.25, resulting in uniform fixation of BiOBr_0.75I_0.25 SS on rGO to yield high-purity BiOBr_0.75I_0.25-rGO heterojunction (BiOBr_0.75I_0.25-rGO HJ) in colloidal dispersion form. The solar-driven fixation of BiOBr_0.75I_0.25 SS on rGO brings many favorable characteristics for BiOBr_0.75I_0.25-rGO HJ as sunlight-responsive photocatalyst over the pristine BiOBr_0.75I_0.25, including high absorption of light in the visible region, high electron-hole separation efficiency, and super adhesive property. As a result, BiOBr_0.75I_0.25-rGO HJ films exhibit super durability and outstanding photocatalytic performance for water decontamination over BiOBr_0.75I_0.25 films under the same conditions. This study is an establishment of a green strategy for the large-scale production of rGO-based bismuth oxyhalides HJs.