A photoluminescence study of nitrogen-doped carbon quantum dots/hydroxyapatite (NCQDs/HAp) nanocomposites

The objective of the present investigation is to functionalise nitrogen-doped carbon quantum dots (NCQDs) with hydroxyapatite (HAp) and study photoluminescence of the composites under ultraviolet radiation. NCQDs were prepared from microwave irradiation of 3:1 molar ratio of urea and citric acid mixture at 750 W for similar to 5 min. HAp was obtained via wet-chemical process from reacting 1 mol of calcium nitrate with 0.6 mol of ammonium dihydrogen phosphate at similar to 37 degrees C for 15 h under basic pH (<8). NCQDs/HAp was synthesised from the hydrothermal method by mixing 5-15 mL aqueous solution of NCQDs with 1 g of HAp and autoclaving the mixtures at 100 degrees C for 1 hour. The samples were characterised using diffraction, spectroscopic and microscopic techniques. Pure and nanoscale crystalline NCQDs/HAp composites, with an average particle size of 45 nm, were observed. The NCQDs/HAp resulted in higher photoluminescence than the HAp.