Carbon quantum dots promote charge transfer of Ce0.7Zr0.3O2@Bi2MoO6 heterojunction for efficient photodegradation of RhB in visible region

Abstract Novel visible light-driven photocatalysts with high separation efficiency of the photo-induced charges urgently need to be developed. In this work, a Ce0.7Zr0.3O2@Bi2MoO6 core-shell heterostructure photocatalyst and carbon quantum dots (CQDs) were fabricated via the hydrothermal method. Establishing a close surfacial contact between the CQD particles and this type-II heterojunction yielded the new CQDs/Ce0.7Zr0.3O2@Bi2MoO6 optical catalytic material. Degradation of the Rhodamine B dye under visible-light irradiation was used to evaluate its catalytic performance. CQDs/Ce0.7Zr0.3O2@Bi2MoO6 exhibited superior and stable activity, which can be attributed to the enrichment of surface oxygen vacancies, more easily driven by visible light, the excellent optical and electronic properties and a lower charge recombination. Various experiments demonstrated that the type-II charge transfer process facilitates the separation of electron-hole pairs at the Ce0.7Zr0.3O2@Bi2MoO6 interface. CQDs can act as cocatalysts to further promote efficient charge separation and transfer in such structure. Moreover, this work presents a mechanism and major active species underlying the reaction on photocatalytic system.