Core-shell structured reduced graphene oxide wrapped magnetically separable rGO@CuZnO@Fe3O4 microspheres as superior photocatalyst for CO2 reduction under visible light

•Novel core-shell structured heterogeneous photocatalyst.•Visible light assisted photoreduction carbon dioxide.•Carbon dioxide utilization to value added chemicals.•Magnetically separable high performance photocatalyst.•Selective synthesis of methanol from carbon dioxide using visible light.

A highly efficient, recyclable and magnetically separable core-shell structured CuZnO@Fe3O4 microsphere wrapped with reduced graphene oxide (rGO@CuZnO@Fe3O4) photocatalyst has been developed and used for the photoreduction of carbon dioxide with water to produce methanol under visible light irradiation. Owing to the synergistic effect of the components and to the presence of a thin Fe2O3 layer on Fe3O4, rGO@CuZnO@Fe3O44 exhibited higher catalytic activity as compared to the other possible combinations such as CuZnO@Fe3O42 and GO@CuZnO@Fe3O43 microspheres. The yield of methanol in case of using 2 and 3 as photocatalyst was found to be 858 and 1749 μmol g−1 cat, respectively. However, the yield was increased to 2656 μmol g−1 cat when rGO@CuZnO@Fe3O44 was used as photocatalyst under similar experimental conditions. This superior photocatalytic activity of 4 was assumed to be due to the restoration of the sp2 hybridized aromatic system in rGO, which facilitated the movement of electrons and resulted in better charge separation. The synthesized heterogeneous photocatalyst could readily be recovered by external magnet and successfully reused for six subsequent cycles without significant loss in the product yield.

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