TiO2 plays a significant role in many applications including solar cell. Consecutively to absorb the low-energy radiation, it is very much essential to tune the optical property of TiO2. We fabricated CeO2-ZnO-TiO2 semiconductor composites by sol-gel method and achieved the absorption of lower energy radiation. The prepared composites were characterized by TG-DTA, UV-DRS, XRD, AFM, TEM and FESEM techniques. The particle and crystalline size of the composites was calculated using FESEM and XRD techniques, respectively. The photocatalytic activity of the synthesized composite for the degradation of Rhodamine B (RhB) under visible light irradiation was investigated. The photocatalytic degradation of RhB under various experimental conditions such as amount of catalyst, initial dye concentration and H2O2 amount was also demonstrated and the rate constant was calculated using L-H model. 1. Introduction Semiconductor metal oxide plays an important role in heterogeneous catalysis, electrochemistry, gas sensors, and other applications. Recently titanium dioxide (TiO2) received a lot of attention due to its chemical stability, nontoxicity, and low cost. TiO2 is used as a gas sensor, antireflection coating in many thin-film optical devices, biomaterials, catalyst/support/additive in catalytic reactions [1–4] and as a good photocatalyst [5, 6]. It is well known that TiO2 absorbs wavelength shorter than 385？nm due to its band gap of about 3.2？eV. Since very narrow range of such high energy radiation is available in solar light spectrum, it is very difficult to convert solar energy to chemical oxidizing power. So, it is very urgent to tune the optical property of TiO2 for utilizing a large fraction of the solar spectrum to realize the indoor applications of this material. For this reason, modification of TiO2 is done by various strategies like coupling with a narrow band gap semiconductor, metal ion/nonmetal ion doping, codoping with two or more foreign ions, surface sensitization by organic dyes or metal complexes, surface fluorination, and noble metal deposition. Nanocomposites such as TiO2-SiO2 [7, 8], ZnO-CdS [9], TiO2-WO3 [10, 11], TiO2-CeO2 [12], TiO2-Fe2O3 [13], In2O3-TiO2 [14], TiO2-CdSe [15], TiO2-CdS [16], and TiO2-ZnO [17] have been considered as effective photocatalysts. Cerium oxide (CeO2) is the most reactive rare earth metal oxide that has broad range applications in various fields [18] and it is an additive in the automotive three-way catalysts [19]. The redox couple of Ce3+/Ce4+ and the high capacity to store oxygen of CeO2 have gained additional
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