Composites Of Bismuth Based Oxide And TiO₂:Preparation And Their Photocatalytic Properties

With the continuous development of global industrialization, more and more organic waste water was discharged into the environment, which caused great harm to human health and ecosystem. Environmental pollution problems have obtained widespread concern of the whole society in recent years. Owning to its advantages of high efficiency, low cost and high security, semiconductor photocatalytic technology has a bright future in the field of environmental pollution control. Although the most commonly used photocatalyst TiO2 is cheap, non-toxic and easy available, its own shortcomings, such as low utilization of sunlight, high recombination rate of the photo-induced electron-hole pairs, also limit its practical applications. Bi2O3 and BiFeO3 have gained extensively interests in the photocatalytic research and applications because of their chemical stability, proper bandgaps for light absorption and environmentally friendly properties. In this work, we prepared BiO3/TiO2 nanotube arrays electrode and BiO3/BiFeO3/TiO2 flower-like composites, and then studied their photocatalytic performances in the degradations of 2-Chlorophenol and Rhodamine B. The main work and results are introduced as follows.(1) The Bi2O3/TiO2 nanotube arrays electrode was prepared combining anodic oxidation and vacuum impregnation methods. The as-prepared samples were studied by morphology, crystal structure and optical absorption characterizations. The modification of Bi2O3 particles enhanced the optical response of the TiO2 nanotube arrays. The photocurrent density and optical conversion efficiency of Bi2O3/TiO2 nanotube arrays were 2.58 and 2 times of TiO2 nanotube arrays, respectively. Under simulated sunlight, the degradation efficiency of the Bi2O3/TiO2 nanotube arrays electrode was 2.25 times of the TiO2 nanotube arrays electrode.(2) The TiO2 nanoflowers and Bi2O3/BiFeO3 nanoparticles were prepared via solvothermal and sol-gel method, respectively. The Bi2O3/BiFeO3/TiO2 flower-like composites were fabricated by adhering Bi2O3/BiFeO3 nanoparticles and TiO2 nanoflowers together. The Bi2O3/BiFeO3 nanoparticles were uniformly dispersed on the surface of TiO2 nanoflowers. UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy analysis results indicated that the modification of Bi2O3/BiFeO3 nanoparticles improved the optical response and the photoinduced charge separation effiency of TiO2 nanoflowers. Under visible light, the degradation efficiency of the Bi2O3/BiFeO3/TiO2 flower-like composites was 3.91 times of TiO2 nanoflowers.