Understanding the interaction of carbon quantum dots with CuO and Cu2O by fluorescence quenching.

Graphical abstract Highlights • Interaction of C-dots with CuO and Cu 2 O nanoparticles by fluorescence quenching is demonstrated. • CuO and Cu 2 O nanoparticles are synthesised by combustion synthesis by mere variation of fuel quantity. • Interaction studies are carried out by steady state and time resolved methods. • CuO is more efficient quencher compared to Cu 2 O. Abstract In spite copper oxide being one of the essential micronutrient, copper oxide in its nano size is found to be toxic in nature; this instigates for the detection of copper oxides in trace levels. In the present study, we demonstrate simple cost effective detection method for CuO/Cu 2 O using carbon quantum dots (CQD) by fluorescence quenching technique. CuO/Cu 2 O nanoparticles are synthesised by mere variation of fuel ratio by solution combustion technique. The resulting oxides are characterized by various analytical and spectroscopic techniques. Powder X- ray diffraction (PXRD) results reveals that samples prepared with oxidizer to fuel (O/F) ratios 1:1, 1:1.5 and 1:2 showed pure nano CuO, major CuO phase (minor Cu 2 O) and major Cu 2 O phase (minor CuO) respectively. Further, the samples prepared using 1:1 O/F ratio and calcinated at 700 °C showed highly crystalline CuO phase. In order to study the interaction of CuO/ Cu 2 O with CQDs the fluorescence quenching method has been employed. The bimolecular quenching rate constants for the samples prepared with different O/F ratios have been measured. The interaction between CQDs and copper oxides, indicates fluorescence quenching greatly depends on the oxidation state of the copper oxide and can be a promising method for detecting CuO/Cu 2 O through CQDs. [ABSTRACT FROM AUTHOR]