Controllable Synthesis Of Bismuth-Based Micro & Nanomaterials And Their Photocatalitic Properties

The materials with layered structure have attracted great interest as their spcial crystal structure and internal static electric field effect can contribute the photoinduced charge separation and transfer. It is worth noting that Bi(Ⅲ) 5d106s2, can hybridize with O-2p orbitals to form a hybridized valence band, which could allow oxide semiconductors of the ions to display a certain absorption in visible light range. Both BiOBr and (BiO)2CO3 have indirect band-gaps helping to reduce the recombination of photo-induced e- and h+,which is of great significance to improve the photocatalytic performance of photocatalyst, However, the simple BiOBr or general (BiO)2CO3 can not satisfy the demond of further improving its photocatalytic performance. Therefore, it is of particular urgence to develop composite or modified Bi-base photocatalysts. The present work is composed of two sections:(1) Improved photocatalytic performance of self-assembled Bi/BiOBr square microflowers with Square Nanopetals. (2) Enhenced photocatalytic performance of self-assembled (BiO)2CO3 microspheres with nanosheets. The key points are as follows:The first section include the following contents:First, the Bi/BiOBr square microflower crystal with square nanopetals having highly uniform dimensions was controllable synthesis by adopted a simple one-pot solvothermal process, In this process the acetaldehyde came from the decomposition of ethylene glycol as reducing agent and metal Bi came from the in situ reduction of BiOBr. Second, by regulating the initial molar ratio of Bi and Br, reaction temperature and reaction time to explore the formation mechanism of Bi/BiOBr square microflower crystal, our results indicated that all the three reaction parameters could be used to control the molar ratio of Bi to BiOBr and produce completely different effects on the surface structure of the composites. Third, Rhodamine B, methylene blue and methyl orange were used to investigate the application of Bi/BiOBr sample in photocatalysis. We noticed that both the molar ratio of Bi to BiOBr and surface structure of the composites have important effects on their photocatalytic performance. In a word, this work represents an important step toward the structural functional characterization of Bi-based composition materials and the development of controllable synthesis of micro/nano-composition structures.Section two includes the following parts:Part one, we investigated the facil synthesis of (BiO)2CO3 microspheres with nanosheets in the presence of trisodium citrate dihydrate and urea. We found that the coordination effect of trisodium citrate dihydrate could release Bi3- slowly, and especially the gradual decomposition of urea to release CO32- could be used to adjust the reaction rate very well. Therefore, the (BiO)2CO3 microspheres with nanosheets with highly monodisperse, neatly morphology and uniform size were successfully synthesized. Several controlled experiments were carried out to investigate the impact of the different molar ratio of urea to Bi3+ as well as the molar ratio of trisodium citrate to Bi3- on the evolution of morphology of the products. Part two, the photocatalytic performance of (BiO)2CO3 microspheres was studied, our results indicated that the photocatalytic performance of (BiO)2CO3 microspheres was higher than other two (BiO)2CO3 samples. Overall, we believe that this work gives new insight into the relationship between Bi-based materials or their photocatalysis.