Novel highly visible-light active ZnBi 2 O 4 -Bi 2 S 3 photocatalysts with various weight percentages of Bi 2 S 3 have been synthesized by a simple two-step co-precipitation and hydrothermal method. The efficacy of the as-prepared ZnBi 2 O 4 -Bi 2 S 3 composites was evaluated for the degradation of Indigo carmine in aqueous solutions under visible light irradiation. It was found that the as-prepared ZnBi 2 O 4 -Bi 2 S 3 composites showed was greatly enhanced photocatalytic activities as compared to that of pristine ZnBi 2 O 4 under visible light, which could be attributed to synergetic effects, charge transfer between ZnBi 2 O 4 and Bi 2 S 3 , as well as the separation efficiency of the photogenerated electrons and holes. The superoxide anion radical was the major active species responsible for the photodegradation process, whereas the contributions of the photoinduced h + and hydroxyl radicals were moderate and minor, respectively. These results demonstrate the feasibility of utilizing ZnBi 2 O 4 -Bi 2 S 3 as potential heterogeneous photocatalysts for environmental remediation. 8À 9] [a] N.

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The influence of ammonia on TiO 2 -MgFe 2 O 4 catalysts synthesized via a hydrolysis and co-precipitation, followed by calcination at 500 o C, was studied. Two different catalysts, TiO 2 -MgFe 2 O 4 (Am) and TiO 2 -MgFe 2 O 4 (W), were prepared using Ti-precursors, which were synthesized by the hydrolysis of Ti-butoxide with and without ammonia. The resulting TiO 2 -MgFe 2 O 4 catalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area measurements, X-ray diffraction, and UV-vis diffuse reflectance techniques. It was revealed that strong electronic coupling exists between the TiO 2 and MgFe 2 O 4 components within the TiO 2 -MgFe 2 O 4 catalysts. Photocatalytic activity toward Rhodamine B (RhB) was investigated in aqueous solution under visible light irradiation. TiO 2 -MgFe 2 O 4 (W) was found to be an effective catalyst and had several advantages over TiO 2 -MgFe 2 O 4 (Am). These results clearly highlight that ammonia had a significant influence on the photocatalytic activity of the TiO 2 -MgFe 2 O 4 catalysts. Therefore, the results reported herein indicate that TiO 2 -MgFe 2 O 4 is a green, low-cost, and highly efficient photocatalyst for environmental remediation.