Self-modified bismuth silicate heterojunction photocatalyst, and preparation method and application thereof

The invention relates to a self-modified bismuth silicate heterojunction photocatalyst, and a preparation method and an application thereof. The method comprises the following steps: S1, adding bismuth nitrate into an aqueous citric acid solution, carrying out stirring, then adding sodium silicate, and carrying out stirring; S2, subjecting a mixed solution obtained in the step S1 to hydrothermal treatment at a temperature of 100 to 240 DEG C for 0.1 to 72 h, and subjecting a product to washing, drying and grinding; and S3, subjecting the product obtained in the step S2 to calcination treatmentat a temperature of 250 to 750 DEG C for 0.1 to 48 h, and carrying out cooling so as to obtain the self-modified bismuth silicate heterojunction photocatalyst, wherein the mol ratio of citric acid tobismuth nitrate is (1-100): (1-100), and the mol ratio of bismuth nitrate to sodium silicate is (1-3): (1-2). The preparation method provided by the invention does not need introduction of elements except for Bi, Si and O, an