Porous peanut-like Bi2O3–BiVO4 composites with heterojunctions: one-step synthesis and their photocatalytic properties

For the first time, porous peanut-like Bi(2)O(3)-BiVO(4) composites with heterojunctions have been synthesized by a one-step mixed solvothermal method with the assistance of a l-lysine template. A mixture of ethylene glycol (EG) and H(2)O (volume ratio of EG-H(2)O = 3:1) is used as the solvent. Unlike the traditional methods, no concentrated HNO(3) and/or NaOH are involved in diluting Bi and V sources in the adopted approach. The as-synthesized peanut-like samples are rough and porous on the surface and to some extent are interior-hollow. The degradation of methylene blue (MB) is employed to evaluate the photocatalytic activity of the Bi(2)O(3)-BiVO(4) composite. It is observed that the composite performs much better than Bi(2)O(3) and BiVO(4), plausibly due to heterojunctions formed between Bi(2)O(3) and BiVO(4). To investigate the relationship between structure and performance, the as-synthesized samples are characterized by XRD, XPS, SEM, TEM (HRTEM), UV-vis DRS, PL and nitrogen adsorption-desorption methods. Additionally, a possible growth mechanism of this hollow peanut-like structure and the separation process of photogenerated electron-hole pairs on the heterojunctions have been discussed.