β-Bi2O3修饰Bi2WO6光催化降解苯酚及其可能机理

采用简单混合法制备了一系列Bi₂O₃/Bi₂WO₆复合光催化剂. 在紫外光降解水中苯酚的过程中, Bi₂O₃/Bi₂WO₆的光催化活性随Bi₂O₃含量的增加呈现先增大后减小的趋势. 当Bi₂O₃最佳负载量等于12.5% (质量分数, w)时, 该复合光催化剂的活性大约是单一Bi₂WO₆的4 倍. 固体样品表征表明, Bi₂O₃主要以β-Bi₂O₃存在, 复合光催化剂是Bi₂O₃和Bi₂WO₆的简单混合物. 此外, 在电催化氧化水的过程中, β-Bi₂O₃/Bi₂WO₆薄膜电极的光电流远大于β-Bi₂O₃和Bi₂WO₆薄膜电极的光电流之和. Bi₂O₃对Bi₂WO₆光催化的促进作用是由于前者接受后者的光生空穴, 提高Bi₂WO₆光生载流子的分离效率, 从而加快了O₂的还原和苯酚的降解.

Improved Photocatalytic Degradation of Phenol over β-Bi2O3 Modified Bi2WO6 and Possible Mechanism

In this study, a series of Bi₂O₃-containing Bi₂WO₆ catalysts were prepared by a simple mixing method. We used the oxidation of phenol in water under UV light as a model reaction, and found that as the amount of Bi₂O₃ in the mixture increased, its photocatalytic activity increased, and then started to decrease. A maximum activity was observed with the catalyst containing 12.5% (mass fraction, w) of Bi₂O₃, about 4 times that of Bi₂WO₆. Solid characterization revealed that the composite was a mixture of β-Bi₂O₃ and Bi₂WO₆. The water oxidation photocurrent over the β-Bi₂O₃/Bi₂WO₆ thin film electrode was much larger than the sum of the photocurrents of the β-Bi₂O₃ and Bi₂WO₆ thin film electrodes. It is proposed that there is a valence hole transfer from Bi₂WO₆ to β-Bi₂O₃, which improves the charge separation efficiency, and consequently increases the rate of phenol degradation.