Metal free boron nitride quantum dots (BNQDs) as ultraviolet driven photo-catalyst for organic waste removal, theoretical calculations and experimental study

This work is aimed to synthesize nanostructured boron nitride quantum dots (BNQDs) that act as photo-catalyst under UV light irradiation. The photocatalyst is appliedto remove organic wastes via photodegradation. BNQDs were characterized using XRD, SEM-EDX, FTIR, UV-Vis and fluorescence spectrophotometry. BNQDs have the energy gap close to 3.79eV. The results show that the obtained band gap value and band edges position are higher than the value of free energy for photo degradation at conduction and valance bands, this proves that the BNQDs is thermodynamically suitable to drive super oxide and hydroxyl radical production. BNQDs is employed to eliminate different pollutants including, dyes and pharmaceuticals. Kinetic was studied as well, the result of kinatic shows that the degradation of Amlodipine and tetracycline at peak 367nm and 375nm areof the second order with a R2 value of 0.98, 0.97 respectively, and first order kinetic in case of Congo red and toluidine blue at peak 497nm, 615nm respectively with a R2 value of 0.96 for both molecules. Reactive oxygen species (ROS) trapping experiments was performed to determine the active species in photo-catalysis mechanism. Based2on experimental data we can conclude that active species h+, e−, O −• and •OH have a significant effect on degradation yield. Regarding computational simulation, the crystal and electronic structures of the BNQDs have been calculated. The lattice parameters were measured with the Perdew-Burke-Ernzerhof (PBE) functional, and the energy gap (Eg) were calculated applying hybrid functionals including (Becke-3 Parameter-Lee-Yang-Parr) B3LYP and (Heyd–Scuseria–Ernzerhof) exchange–correlation functional HSE06. B3LYP provided better results and closer to the experimental data, given that 2eV as an indirect band gap and thus, B3LYP exchange function was utilized to analyze the band structures and density of states.