微结构优化与GO耦合大幅提高(BiO)_2CO_3可见光催化性能

The mechanism of enhanced visible light photocatalysis with micro-structurally optimized and graphene oxide coupled (BiO)_2CO_3

以柠檬酸铋、无水碳酸钠和氧化石墨烯(GO)为原料,采用一步水热法合成(Bi O)2CO3与GO复合的新型三维(3D)分级结构光催化剂(BOC-GO).通过X射线衍射、扫描电子显微镜、透射电子显微镜、傅里叶红外光谱、拉曼光谱、X射线光电子能谱、表面积测定、紫外可见漫反射光谱和荧光光谱对样品进行表征分析.结果表明,(Bi O)2CO3微球分散在GO薄膜上,形成了新颖的3D分级结构.这种特殊的新结构作为光催化剂,在可见光照射下对ppb级NO(1ppb=1μg/m3)表现出了大幅增强的可见光催化活性和良好的光化学稳定性,远高于(Bi O)2CO3以及其他可见光催化剂.BOC-GO优异的活性可归因于3D分级结构与GO的耦合.一方面(Bi O)2CO3微球特殊的3D分层结构,既能诱导入射光产生多次的散射和反射效应,增加对可见光的捕获利用,也能促进光催化过程中反应物和中间产物的快速转移和运输,为催化剂提供更多的活性位点;另一方面归因于GO自身优越的电子迁移能力,能够将(Bi O)2CO3的导带电子迅速转移和运输,从而促进(Bi O)2CO3上电子-空穴对的有效分离.将光催化剂自身微结构优化与GO耦合是一种大幅提高可见光催化性能的新方法.

The novel 3D hierarchical structure of （BiO）2CO3 coupled with graphene oxide （GO） were fabricated by a one-pot hydrotherrnal method using bismuth citrate, sodium carbonate and GO as precursors. The as-prepared samples were systematically characterized by XRD, SEM, TEM, FT-IR, Raman, BET, UV-vis DRS and PL. The results indicated that （BiO）2CO3 hierarchical microspheres were dispersed on GO films and novel 3D hierarchical structure was formed. The novel 3D structure exhibited outstanding photocatalytic activity and photochemical stability towards degradation of NO at gg/ma-level under visible light irradiation, much higher than that of （BiO）2CO3 and other well-known visible light photocatalysts. The outstanding activity can be ascribed to the special 3D hierarchical architecture of （BiO）2CO3 and superior charge carder mobility of GO. On one hand, the 3D hierarchical architecture can capture more visible light due to the multiple surface scattering and reflecting effects. Also, the hierarchical architecture can function as transport path for reactants and intermediate products and provide more active sites in photocatalsis. On the other hand, the superior charge carrier mobility of GO could facilitate the transfer of exited electrons from conduction band of （BiO）2CO3 to GO, effectively preventing the recombination of electron-hole pairs. Combination of micro-structural optimization and GO coupling is a novel approach for efficiently promoting the visible light photocatalysis. This work could provide a new perspective for controlled synthesis of GO-based photocatalytic materials and mechanism understanding and also new materials for high-performance degradation of environmental pollutants and solar energy conversion.