异质结型AgBr/CuO光催化剂的合成、 光催化活性及再生

采用沉淀法制备了具有p-n异质结结构的AgBr/CuO可见光催化剂, 对其结构进行了表征, 通过甲基橙溶液的降解率评价了AgBr/CuO的光催化活性, 并通过活性物种测试及能带结构分析推测了其光催化机理, 采用3%(质量分数)溴水对使用后的AgBr/CuO进行了再生处理. 结果表明, 在可见光照射下, 0.1 g AgBr/CuO光催化剂30 min对甲基橙溶液(初始浓度为15 mg/L)的降解率高达92%, 远高于同等条件下的AgBr. AgBr/CuO光催化活性提高的原因是AgBr与CuO的复合一方面使催化剂的禁带宽度变宽, 提高了光生电子与光生空穴的氧化还原能力; 另一方面, 在两者之间形成了p-n型异质结结构, 有利于光生电子的转移及光生电子与空穴的分离. 采用绿色环保的溴水再生法可显著恢复催化剂的光催化活性.

Synthesis,Photocatalytic Activity and Regeneration of AgBr/CuO Heterojunction Photocatalyst†

AgBr/CuO p-n heterojunction photocatalyst was prepared by precipitation method and characterized by X-ray diffraction(XRD), UV-Vis spectroscopy(UV-Vis), field emission scanning electron microscopy(FESEM) and X-ray photoelectron spectroscopy(XPS), respectively. The photocatalytic mechanism was speculated through active species test and band structure analysis. Besides, the used AgBr/CuO was regenerated by 3%(mass fraction) bromine water. The results show that the degradation rate of methyl orange(c₀=15 mg/L) over 0.1 g AgBr/CuO was maintained at 92% after 30 min, which was much higher than that over pure AgBr under the same conditions. The reasons for improving the photocatalytic activity of AgBr/CuO photocatalyst are that the band gap of AgBr/CuO photocatalyst become wider and the p-n heterojunction structure is formed between AgBr and CuO. The wider band gap was benefit for the redox ability of photogenerated electrons and photogenerated holes. The p-n heterojunction structure of photocatalyst could accelerate the shift of electrons and the separation of e^--h⁺. In addition, the use of bromine water regeneration method could significantly restore photocatalytic activity.