Preparing Bi12SiO20 crystals at low temperature through nontopotactic solid-state transformation and improving its photocatalytic activity by etching

摘要: Well-crystalline bismuth silicon oxide (Bi12SiO20; BSO) particles were prepared from the reaction of Na2SiO3 (or SiO2) and a oxo compound such as Bi(NO3)3, α-Bi2O3, (BiO)2CO3 or BiOX (X = Cl, Br) in alkaline aqueous solution at 70 °C for 3 h, whereas conventional syntheses melt necessitate above 650 °C. All reactions different precursors experienced same intermediate α-Bi2O3 to final product BSO with cubic triangular pyramidal shape, depending upon NaOH concentration Bi/Si molar ratio. Although photocatalytic efficiency obtained microcrystallites was poor due large particle size associated low specific surface area, we successfully overcame disadvantage insufficient active sites on through etching. The etched crystals possessed rough exhibited enhanced activity RhB degradation under visible light irradiation. Especially, uniform egg-tart shaped BiOCl hierarchical microstructures assembled by nanosheets produced tuning etchant concentration, looking like man-made solar energy acceptor, which superior decomposition comparison its precursor BSO.