Exfoliation Of G-C₃N₄ For Preparation And Property Research Of G-C₃N₄/BiOBr Photocatalyst

Semiconductor photocatalysis technology has broad prospect in pollution treatment and clean energy development. It’s an effective means to address the increasingly serious energy crisis and environmental pollution problems. g-C₃N₄ is a kind of visible-light response photocatalyst which has excellent thermal stability and chemical stability. What’s more, g-C₃N₄ has some advantages such as simple preparation process, low production cost, non-toxic and it can be recycled and reused. It’s a perfect photocatalysis. However the specific surface area of g-C₃N₄ is small and the recombination efficiency of photo-generated electrons and holes is high.g-C₃N₄ nanosheet was prepared by a simple chemical exfoliation method in order to increase the specific surface area of g-C₃N₄. Physical and chemical properties and photocatalytic activity of the prepared samples were preliminary studied in this paper. X-ray diffraction patterns, SEM&HRTEM pictures and FT-IR spectrums indicate that g-C₃N₄ nanosheet has the same chemical structure with g-C₃N₄. The result of BET specific surface area test reveals that the specific surface area of g-C₃N₄ nanosheet is 5.3 times as much as g-C₃N₄. The g-C₃N₄ nanosheet shows higher photocatalytic activity in the photocatalytic degradation experiments, and the photocatalytic degradation efficiency of methyl orange can reach 93.5 % in 2 h. The prepared g-C₃N₄（300 mg） was mixed with 12 mL of concentrated sulfuric acid and magnetic stirred for 60 min at room temperature. Then the mixture was slowly poured into 150 mL of deionizedwater. The g-C₃N₄ nanosheet with highest photocatalytic activity was prepared under this condition.In addition, heterojunction was constituted by coupled g-C₃N₄ nanosheet with BiOBr. It’s an ideal way to improve the separation efficiency of photo-generated electrons and holes. Physical and chemical properties and photocatalytic activity of the prepared samples were preliminary studied. X-ray diffraction patterns, TEM&HRTEM pictures and FT-IR spectrums indicate that the prepared composite photocatalyst was comprised by g-C₃N₄ nanosheet and BiOBr. Thermogravimetric analysis reveals that the prepared composite photocatalyst was provided with favourable thermal stability. Compared with the single g-C₃N₄ nanosheet and BiOBr, the prepared composite photocatalyst shows excellent photocatalytic activity in the photocatalytic degradation experiments. When the composite photocatalyst was comprised of 30% BiOBr and 70% g-C₃N₄ nanosheet, it has the highest photocatalytic activity and the photocatalytic degradation efficiency of methyl orange can reach 99.7 % in 2 h. Separation efficiency of photo-generated electrons and holes was improved in the composite photocatalyst because of the existence of the heterojunction. So the photocatalytic activity of composite photocatalyst is much higher than that of mechanical mixed potocatalyst.