The synthesis of bismuth vanadate powders and their photocatalytic properties under visible light irradiation

Bismuth vanadate powders were prepared by hydrothermal method with NaVO3 and Bi(NO3)3 as starting materials and with Na2CO3 to adjust pH, and characterized by XRD, SEM, EDS and surface area analyzer. The results showed that the phase formation of bismuth vanadate depended on the adding amount of Na2CO3. The bismuth vanadate samples existed as monoclinic BiVO4 by adding 0.019 and 0.038 mol of Na2CO3 with corresponding pH value of 0.2 and 5.8, respectively, and as Bi4V2O11 by adding 0.057 mol of Na2CO3 with corresponding pH value of 9.7. The photocatalytic activities of the samples were evaluated by the decolorization of methylene blue (MB) under visible light irradiation. The sample with monoclinic form obtained by adding 0.019 mol of Na2CO3 had the highest photocatalytic activity, the decolorization rate of MB reached to 96.4% under visible light irradiation in 200 min and the reaction rate constant was 0.015 min−1.