Fu Hongbo, Pan Chengshi, Yao Wenqing, Zhu Yongfa
Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China.
J Phys Chem B. 2005 Dec 1;109(47):22432-9. doi: 10.1021/jp052995j.
Visible-light-induced photodegradation of rhodamine B over nanosized Bi2WO6 has been observed. Bi2WO6 exhibited a high photoactivity to photodegrade rhodamine B in the central pH solution under visible irradiation (lambda > 420 nm). After five recycles for the photodegradation of rhodamine B, the catalyst did not exhibit any significant loss of activity, confirming the photocatalyst is essentially stable. The total organic carbon measurement displayed that a high degree of mineralization was achieved in the present photochemical system. The results of density functional theory calculation illuminated that the visible-light absorption band in the Bi2WO6 catalyst is attributed to the band transition from the hybrid orbitals of Bi6s and O2p to the W5d orbitals. The Bi2WO6-assisted photocatalytic degradation of rhodamine occurs via two competitive processes: a photocatalytic process and a photosensitized process. The transformation of rhodamine is mainly via the photocatalytic process. Kinetic studies by using electron spin resonance and the radical scavenger technologies suggest that OH is not the dominant photooxidant. Direct hole transfers and O2- could take part in Bi2WO6 photocatalysis. This study provided a possible treatment approach for organic pollutants by using visible light in aqueous ecosystems.
已观察到纳米Bi2WO6对罗丹明B的可见光诱导光降解。在可见光照射（λ>420nm）下，Bi2WO6在中性pH溶液中对罗丹明B的光降解表现出高光活性。在对罗丹明B进行五次光降解循环后，催化剂没有表现出任何明显的活性损失，证实了光催化剂基本稳定。总有机碳测量表明，在本光化学体系中实现了高度矿化。密度泛函理论计算结果表明，Bi2WO6催化剂中的可见光吸收带归因于从Bi6s和O2p的杂化轨道到W5d轨道的能带跃迁。Bi2WO6辅助的罗丹明光催化降解通过两个竞争过程发生：光催化过程和光敏化过程。罗丹明的转化主要通过光催化过程。利用电子自旋共振和自由基清除剂技术进行的动力学研究表明，OH不是主要的光氧化剂。直接空穴转移和O2-可参与Bi2WO6光催化。本研究为在水生生态系统中利用可见光处理有机污染物提供了一种可能的方法。
