Integration of orange peel derived carbon quantum dots with TiO2 for enhanced photocatalytic degradation of brilliant green dye

Abstract

Brilliant green (BG) dye is a non-biodegradable, highly venomous and coloured pigment. BG dye possesses remarkably high visibility even at small concentration that causes diarrhea and abdominal pain in humans when being ingested. In addition, it is harmful to living organisms and polluting aquatic environments. Hence, eliminating BG dye from contaminated water is an urgent need. In this report, a photocatalyst encompasses hydrothermally prepared titanium dioxide (TiO2) integrated with orange peel derived oxygenated carbon quantum dots (O-CQDs) was developed for effective removal of BG dye. The O-CQDs were prepared using a single step eco-friendly hydrothermal process and an intense green fluorescence was observed upon exposing the O-CQDs to far UV light irradiation (254 nm). The formation of TiO2/O-CQDs nanohybrid was confirmed through UV–Visible spectrophotometer, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS) analyses. A random distribution of spherical shaped O-CQDs on the surface of TiO2 was clearly observed in FESEM images. The carboxyl groups present in O-CQDs not only increased interlayer spacing but also led to the attachment of TiO2 effectively. The TiO2/O-CQDs nanohybrid showed 94.70 % efficiency towards photocatalytic degradation of BG dye under UV light irradiation that was ∼20 % higher than the efficiency of pristine TiO2 photocatalyst. The presence of O-CQDs in the TiO2/O-CQDs nanohybrid boosted the photocatalytic degradation efficiency by enhancing UV light absorption and suppressing photo-generated electron–hole recombination. The integration of agricultural waste derived carbon with TiO2 by a facile synthesis method paves a way for large scale synthesis of TiO2/O-CQDs nanohybrid, which is anticipated to broaden its application potential in environmental remediation through photocatalytic degradation of organic compounds.