Unravelling the interfacial interaction in mesoporous SiO₂@nickel phyllosilicate/TiO₂ core-shell nanostructures for...

Core-shell based nanostructures are attractive candidates for photocatalysis owing to their tunable physicochemical properties, their interfacial contact effects, and their efficacy in charge-carrier separation. This study reports, for the first time, on the synthesis of mesoporous silica@nickel phyllosilicate/titania (mSiO₂@NiPS/TiO₂) core-shell nanostructures. The TEM results showed that the mSiO₂@NiPS composite has a core-shell nanostructure with a unique flake-like shell morphology. XPS analysis revealed the successful formation of 1:1 nickel phyllosilicate on the SiO₂ surface. The addition of TiO₂ to the mSiO₂@NiPS yielded the mSiO₂@NiPS/TiO₂ composite. The bandgap energy of mSiO₂@NiPS and of mSiO₂@NiPS/TiO₂ were estimated to be 2.05 and 2.68 eV, respectively, indicating the role of titania in tuning the optoelectronic properties of the SiO₂@nickel phyllosilicate. As a proof of concept, the core-shell nanostructures were used as photocatalysts for the degradation of methyl violet dye and the degradation efficiencies were found to be 72% and 99% for the mSiO₂@NiPS and the mSiO₂@NiPS/TiO₂ nanostructures, respectively. Furthermore, a recyclability test revealed good stability and recyclability of the mSiO₂@NiPS/TiO₂ photocatalyst with a degradation efficacy of 93% after three cycles. The porous flake-like morphology of the nickel phyllosilicate acted as a suitable support for the TiO₂ nanoparticles. Further, a coating of TiO₂ on the mSiO₂@NiPS surface greatly affected the surface features and optoelectronic properties of the core-shell nanostructure and yielded superior photocatalytic properties.