Improving the Fluorescence of Carbon Dots Through Boron and Silver Doping: A Single-Step Microwave Synthesis Approach

Abstract

Carbon dots (CDs) are a promising type of fluorophore with numerous advantages such as low toxicity, biocompatibility, good photostability, and ease of synthesis. However, their low quantum yields (QYs) have limited their applicability in many fields. Researchers have turned to doping CDs with nonmetallic and metallic atoms to address this issue. In this study, we synthesized citric acid/urea-based CDs doped with boron and/or silver atoms in a single step using microwave irradiation. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the CDs. In contrast, UV-visible (UV-Vis) and fluorescence spectroscopy were used to examine their optical properties. We discovered that all synthesized CDs were transparent to visible light and emitted blue fluorescence when exposed to UV light. Our fluorescence analysis revealed that doping with both boron and silver atoms led to higher fluorescence compared to doping with only one of the atoms. Specifically, the quantum yields (QYs) of silver/boron-doped CDs were 26%, which is higher than those of silver-doped CDs (19%), boron-doped CDs (9%), and undoped CDs (6%). These findings suggest that the silver/boron-doped CDs produced using our simple method could be promising materials for sensors and biomedical applications.