N-doped carbon quantum dots for the detection of 4-nitrophenol, antioxidant activity, and synthesis of Fe 3 O 4 CuO@CQD as a catalyst for the reduction of 4-nitroaniline

In this work, raw turmeric and l-arginine were used as the source in the hydrothermal process to synthesize nitrogen-doped carbon quantum dots (NCQDs) in an environmentally friendly, greener manner. Because of their excellent photoluminescence, quantum yield of 36.40%, and their water solubility, the NCQDs were investigated for their multifunctional applications. As a result, they were used as a sensor for the selective detection of 4-nitrophenol (4-NP). 30 nM was determined to be the limit of detection (LoD). It also shows strong antioxidant efficacy, which was evaluated using DPPH free radical scavenging. Additionally, the NCQDs stabilized the synthesis of the FeO4CuO@CQD nanocomposite and were characterized using various methods to ascertain their catalytic efficiency. Subsequently, 4-nitroaniline (4-NA) was reduced to p-phenylenediamine aided by these nanocomposites.