High photocatalytic activity over starfish-like La-doped ZnO/SiO2 photocatalyst for malachite green degradation under visible light

• 作者: Shuo Wang Zhenke Chen Ying Zhao Chenlu Sun Jianye Li
• 来源期刊: 稀土学报（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: RARE EARTH CATALYSIS
• 页码范围: 772-780
• 页数: 9页
• 语种: 英文

摘要

In this work, the unique starlike La-doped ZnO-SiO2 photocatalysts were constructed by an evaporation and calcination method and characterized in detail. UV-vis reflectance and DFT calculation confirm that the doping with La allows to obtain a decrease of band gap of ZnO/SiO2, which enhances visible light absorbance and oxidizing ability. The photoluminescence intensity reduces greatly, indicating more effective separation of the photogenerated carriers of La-doped ZnO-SiO2. Photocatalytic activities of La-doped ZnO-SiO2 with different doping ratios under simulated visible light irradiation were evaluated with malachite green (MG) as a model pollutant. Under optimized conditions including solution pH of 8, 15 mg/L of MG solution and 15 mg of catalyst dosage, 0.2％La-ZnO-SiO2 exhibits the best catalytic activity in photodegradations of MG in water. The removal and mineralization efficiency of MG can reach 96.1％and 70.9％in 140 min, respectively. The as-prepared catalysts present superior stability and recyclability after four times reuse. Moreover, selective quenching experiments indicate that hydroxyl radical (?OH), hole (h+) and superoxide radical (?O2-) are the main reactive species responsible for MG degradation. Possible mechanism for photocatalytic elimination of MG over La-doped ZnO/SiO2 photocatalyst is finally proposed.