α-Fe₂O₃纳米材料的固相合成及光催化降解亚甲基蓝性能

Solid-State Synthesis of α-Fe₂O₃ Nanomaterials and Photocatalytic Degradation Performance on Methylene Blue

摘要: 采用固相法首先制备前驱体，然后不同温度热处理得到α-Fe₂O₃纳米材料，采用XRD、FTIR、FESEM、DRS等多种表征手段分析了材料的晶体结构、微观形貌与光学性能。结果表明，热处理温度升高，α-Fe₂O₃纳米材料粒径逐渐增大，其带隙宽度也逐渐升高，但均小于体相α-Fe₂O₃的带隙宽度(2.2 eV)。500℃热处理2 h所得α-Fe₂O₃纳米材料具有最高的可见光光催化效率和光降解速率常数，其分别为70.60%和6.78 × 10−3 min−1，太高或太低的热处理温度均会导致光催化效率降低，这主要受带隙大小和电子–空穴复合机率影响。

Abstract: Precursors were synthesized by a solid-state synthesis method. And α-Fe₂O₃ nanomaterials were obtained by thermal decomposition of precursors at different calcination temperatures. The crystal structure, microstructure morphology and optical properties of the α-Fe₂O₃ nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field scanning electron microscopy (FESEM), and UV-vis diffuse reflectance spectroscopy (DRS). The results show that the energy gap and particle size of the α-Fe2O3 nanomaterials increase with annealing temperature. But they are all less than bulk α-Fe₂O₃ (2.2 eV). The α-Fe₂O₃ nanoparticles prepared at 500˚C for 2 h exhibit the highest visible-light photocatalytic efficiency of 70.60% and photodegradation rate constant, k, of 6.78 × 10−3 min−1, respectively. Too high or too low heat treatment temperature will result in the decrease of photocatalytic efficiency, which is mainly affected by band gap and electron-hole recombination probability.