Carbonized propagation synthesis of porous CQDs–SrTiO3/graphene and its photocatalytic performance for removal of methylene blue

A porous carbon quantum dots (CQDs)–SrTiO3/graphene material (CSG) was synthesized using a novel sol–gel carbonized propagation method (SCPM). In this method, the prepared gel was first immersed in an organic solvent with low-temperature self-propagating properties, and after being ignited, the product is obtained through carbonized propagation processes. Various characterization studies showed that CQDs, SrTiO3 and graphene can be combined through the SCPM, and CQDs and SrTiO3 form a heterojunction on the surface of the material, which is conducive to the recovery of the photocatalyst and improvement of the photocatalytic performance. The existence of a reducing atmosphere resulted in the occurrence of the doping process of CQDs. Photocatalytic degradation experiments showed that, with the increase of ethanol consumption, the catalytic performance tends to be stable. CSG-5, which consumes 80 mL of ethanol, has the best effect on MB degradation. When the dosage is 1.5 g L−1 and the concentration of MB is 5 mg L−1, the degradation rate is 94%. h+ and ˙O2− played a major role in the degradation system of CSG-5. UPLC-MS/MS results showed that 8 kinds of intermediates were produced during the degradation process. The special structure and preparation method of CSG-5 might help to prepare better photocatalysts.