Influence of interface combination of RGO-photosensitized SnO ₂ @RGO core-shell structures on their photocatalytic performance

SnO ₂ @reduced graphene oxide (RGO) core-shell structures were successfully synthesized by two different strategies (electrostatic interaction method and direct chemical bonding reaction method). The investigation of morphologies and microstructures showed that RGO was wrapped tightly on the surface of SnO ₂ microspheres with different interface combinations, i.e., electrostatic interaction and chemical bonding. Raman spectroscopy and photoluminescence (PL) spectra demonstrated that graphene as a photosensitizer could transfer photogenerated electrons to the conduction band (CB) of SnO ₂ and receive holes from the valence band (VB) of SnO ₂ , resulting in the separation of photogenerated electron-hole pairs. The photocatalytic activity of the synthesized composites was evaluated by the photodegradation of methyl orange (MO) under ultraviolet (UV) light irradiation. It was found that SnO ₂ @RGO with chemical bonding interface combination exhibited higher photodegradation rate (k = 0.038 min ⁻¹ ) than those with electrostatic interaction interface combination (k = 0.021 min ⁻¹ ) and pure SnO ₂ (k = 0.010 min ⁻¹ ). The enhanced photocatalytic activity could be attributed to the photosensitization of RGO and the intimate interface combination between SnO ₂ and RGO.