Carbon Dots Synthesis from Soybean with Urea Doped As Sensitive Fe (II) Ion Detection

Abstract

Synthesis of carbon dots from soybeans with urea doped (N-CDs) has been successfully conducted using the bottom-up approach via the hydrothermal method. The N-CDs showed a dark brown solution, indicating the carbon dots formed. This study analyzed the effect of optical properties before and after Fe (II) ions addition on the sensitivity of N-CDs. N-CDs characterizations were analyzed using UV-Vis Spectrophotometer and Photoluminescence Spectroscopy (PL). The results showed that the absorbance spectrum range is from 200 to 600 nm, with its absorbance peak at 290 nm. The band gap energy obtained is 3.32 eV, which indicates that N-CDs are semiconductors. The N-CDs solution resulted in good fluorescence when observed under ultraviolet light (395 nm) and emitted a bright green color. N-CDs' sensitivity when sensing Fe (II) ions with a minimum Limit of Detection (LOD) is as low as 5.7 nM. Thus, N-CDs can be used as biosensors with an easy and environmentally friendly method.