VIS-active TiO₂ films decorated by expanded graphite: impact of the exfoliation time on the photocatalytic behaviour

ABSTRACT

TiO₂/C nanocomposite films were applied on water treatment. Expanded graphite nanosheets (EG) were obtained by UVC-assisted liquid-phase exfoliation technique, without the addition of acids, surfactants, or aggressive oxidizing agents, which characterizes the process as an eco-friendly method. The carbon nanosheets were synthesized directly from graphite bulk at different times and deposited on TiO₂ films surface by airbrush spray coating method, forming a TiO₂/C heterojunction. The increase in the exfoliation time promoted a more efficient photocatalytic dye removal under visible light. Morphological modifications, changes in the electronic structure, and wide range of light absorption were observed from the TiO₂/C heterojunction formation. The results showed that hybrid TiO₂/C supported photocatalyst is a promise alternative for practical photocatalytic applications under sunlight.

GRAPHICAL ABSTRACT

KEYWORDS:

• Expanded graphite
• TiO₂
• liquid-phase exfoliation
• photocatalysis
• heterojunction

Acknowledgements

The authors are grateful to CNPq (National Council for Scientific and Technological Development, Proc. 168935/2018-0) Brazilian agency for the financial support, and the Polytechnic School of the University of São Paulo (Electrical Engineering School of POLI-USP) for the Raman spectroscopy and UV-vis spectrophotometry facility.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analysed during this study are included in this published article (and its supplementary information files), and are available from the corresponding author on reasonable request.

Additional information

Funding

This work was supported by CNPQ [grant number 168935/2018-0].