Selenium-Doped Carbon Dots for Enhanced Electrochemical Energy Storage

Carbon dots (C-dots) are widely used in energy storage applications due to their exceptional electrical properties. Doping enhances their performance by tailoring structural and electronic characteristics. In this study, C-dots, nano-selenium (n-Se), and selenium-doped C-dots (Se-C-dots) are synthesized via a hydrothermal process and characterized for size, morphology, crystallinity, and thermal stability. The mean diameters of C-dots and Se-C-dots are approximately 9.5 nm, while n-Se measures 22.0 nm. Se-C-dots and n-Se exhibit thermal stability up to 465.5 °C and 450 °C, respectively, whereas C-dots remain stable up to 281 °C. The Se-C-dot composition includes 84% Se and 16% C-dots. Electrical conductivity values are 0.077 mS cm−1 for C-dots and 0.069 mS cm−1 for both n-Se and Se-C-dots. Despite a slight decrease in conductivity, Se-C-dots demonstrate superior electrochemical behavior, achieving a specific capacitance of 148.9 F g−1 compared to 133.1 F g−1 for C-dots and 139.2 F g−1 for n-Se. Furthermore, Se-C-dots deliver a maximum energy density of 29.8 Wh kg−1 at 10 mV s−1 and a power density of 3462.6 W kg−1 at 100 mV s−1, outperforming C-dots across various scan rates. These findings confirm the beneficial influence of selenium incorporation and highlight the potential of Se-C-dots as promising electrode materials for high-performance supercapacitors.