The BiVO4 microspheres and Sm3+-doped BiVO4 polygons were prepared via a facile hydrothermal method by means of K6V10O28 center dot 9H(2)O as a novel vanadium source. Optimized temperature and pH value of prepared BiVO4 were obtained. The polycrystalline BiVO4 microspheres prepared at T = 140 A degrees C, pH 4, demonstrates the best photocatalytic activities for degrading dyes under UV radiation. This is resulted due to transfers of photogenerated electrons from tetragonal to monoclinic phases. In contrast to the undoped BiVO4, the photocatalytic activity of Sm3+-doped BiVO4 polygons is drastically enhanced not only under UV radiation but also under visible light radiation. The optimized Sm content was found to be 10 %. Enhanced efficiency with the doped sample is attributed to the dopants' role in blocking recombination of photogenerated electron-hole pairs. This work offers a simple route to obtain mixed phase BiVO4 and provide an effective way to achieve higher photocatalytic activity by doping the Sm3+ in the semiconductor catalysts.