Synthesis of heterojunction photocatalysts composed of Ag2S quantum dots combined with Bi(4)Ti(3)O(12)nanosheets for the degradation of dyes
Synthesis of heterojunction photocatalysts composed of Ag2S quantum dots combined with Bi(4)Ti(3)O(12)nanosheets for the degradation of dyes
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Ag2S量子点与Bi(4)Ti(3)O(12)纳米片复合异质结光催化剂的合成用于降解染料
DOI：
10.1007/s11356-018-4050-3
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发表时间：
2019
影响因子：
5.8
通讯作者：
Liu Xueqin
中科院分区：
文献类型：
--
作者：
Zhao Xinxin;Yang Hua;Li Ruishan;Cui Ziming;Liu Xueqin
促进光生电子/空穴对的分离和拓宽光响应区域是提高光催化剂整体光催化性能的关键。为了实现这一目标，本文通过在Bi 4 Ti 3 O 12纳米片表面组装Ag 2S量子点，制备了Ag 2S/Bi 4 Ti 3 O 12异质结复合光催化剂。透射电子显微镜观察表明，在大尺寸Bi 4 Ti 3 O 12纳米薄片表面均匀组装了尺寸分别为40-70 nm和7-17 nm的Ag 2S量子点。所制备的Ag 2S/Bi 4 Ti 3 O 12异质结复合材料表现出更强的光吸收（特别是在可见光和近红外区域）和Bi 4 Ti 3 O 12中光生电子和空穴的高效分离。以罗丹明B（RhB）水溶液为目标有机污染物，在模拟太阳光照射下考察了样品的光催化性能。结果表明，Ag 2S/Bi 4 Ti 3 O 12异质结复合材料对RhB的光催化降解具有显著的增强作用。其中，15wt%Ag_2S/Bi_4Ti_3O_（12）复合材料的光催化活性最高，约为100%。2.8比未掺杂的Bi_4 Ti_3 O_（12）和Ag_2S分别高4.0倍。复合材料光催化活性的提高是由于电子从Bi 4 Ti 3 O 12的导带向Ag 2S的价带进行Z型转移，使更多的Bi 4 Ti 3 O 12价带中的光生空穴和Ag 2S导带中的电子参与光催化反应。进行了活性物种捕获实验，得出光生空穴和·O2-自由基在光催化中分别起主导和次要作用的结论。
Facilitating the separation of photogenerated electron/hole pairs and widening the light-responsive region are crucial to enhance the overall photocatalytic performance of photocatalysts. To achieve this aim, here we have prepared Ag2S/Bi4Ti3O12heterojunction composite photocatalysts by assembling Ag2S quantum dots onto the surface of Bi4Ti3O12nanosheets. Transmission electron microscopy observation demonstrates that two types of Ag2S quantum dots separately with size of 40–70 and 7–17 nm are uniformly assembled onto the surface of large-sized Bi4Ti3O12thin nanosheets. The as-prepared Ag2S/Bi4Ti3O12heterojunction composites exhibit much enhanced light absorption (particularly in the visible and near-infrared region) and highly efficient separation of electrons and holes photogenerated in Bi4Ti3O12. Rhodamine B (RhB) aqueous solution was chosen as the target organic pollutant to evaluate the photocatalytic performance of the samples under simulated sunlight irradiation. It is found that the Ag2S/Bi4Ti3O12heterojunction composites manifest significantly enhanced photocatalytic activity toward the RhB degradaton. In particular, the 15wt% Ag2S/Bi4Ti3O12composite exhibits the highest photocatalytic activity, which is ca. 2.8 and 4.0 times higher than bare Bi4Ti3O12and Ag2S, respectively. The enhanced photocatalytic activity of the composites can be explained as a result of the Z-scheme electron transfer from the conduction band of Bi4Ti3O12to the valence band of Ag2S, and thus more photogenerated holes in the valence band of Bi4Ti3O12and electrons in the conduction band of Ag2S are able to participate in the photocatalytic reactions. Active species trapping experiments were carried out, from which it is concluded that photogenerated holes and •O2−radicals play the dominant and secondary role in the photocatalysis, respectively.