Preparation method for bismuth vanadate

The invention relates to a preparation method for bismuth vanadate. The preparation method comprises the following steps (based on parts by weight): (1) slowly adding a metavanadic acid compound and sodium hydroxide into water and dispersing the two uniformly to prepare a metavanadic acid compound solution for later use; (2) sequentially adding water, a bismuth source and a stabilizer into a reactor, performing magnetic stirring of the mixture, and adding the metavanadic acid compound solution prepared in the step (1) for magnetic stirring and aging to prepare a reaction solution; and (3) adjusting the pH of the reaction liquid prepared in the step (2) by using a sodium hydroxide solution, adjusting the temperature, stirring the mixture for reaction, and cooling the mixture to the room temperature, thereby obtaining a bismuth vanadate solution. The preparation method provided by the invention overcomes the defects that most bismuth vanadate catalysts prepared in an existing process are solid and cannot be directly applied to a medium or an external wall cover, and has the advantages that the produced bismuth vanadate is suitable for and directly applicable to construction of the medium or the external wall cover.