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

Bridget K Mutuma; Xiluva Mathebula; Isaac Nongwe; Bonakele P Mtolo; Boitumelo J Matsoso; Rudolph Erasmus; Zikhona Tetana; Neil J Coville

doi:10.3762/bjnano.11.165

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

Beilstein J Nanotechnol. 2020 Dec 9:11:1834-1846. doi: 10.3762/bjnano.11.165. eCollection 2020.

Authors

Bridget K Mutuma¹, Xiluva Mathebula¹, Isaac Nongwe², Bonakele P Mtolo¹, Boitumelo J Matsoso¹, Rudolph Erasmus³, Zikhona Tetana¹, Neil J Coville¹

Affiliations

¹ DSI-NRF Centre of Excellence in Strong Materials and Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, WITS 2050, Johannesburg, South Africa.
² Department of Natural Resources and Materials, Botswana Institute for Technology Research and Innovation, 50654 Machel Drive, Gaborone, Botswana.
³ School of Physics, University of Witwatersrand, WITS 2050, Johannesburg, South Africa.

Abstract

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.

Keywords: bandgap energy; core–shell; dye degradation; nickel phyllosilicate; photocatalysts.

Grants and funding

We would like to acknowledge the financial support received from the NRF, the University of the Witwatersrand and the DSI-NRF Centre of Excellence in Strong Materials. B. Mutuma acknowledges the University of Witwatersrand for the postdoctoral research fellowship.