Enhancing ZnO-based supercapacitors through carbon-induced defect centers

Abstract

This study explores the effects of eco-friendly reducing and capping agents on synthesizing zinc oxide (ZnO) nanoparticles for use as electrode materials in supercapacitors. The researchers successfully produced ZnO nanoparticles with different sizes and shapes using a sol-gel method and four different capping agents: tartaric acid, chitosan, ascorbic acid, and hydroxybenzoic acid. The properties of the ZnO nanoparticles were thoroughly examined through morphological, structural, and electrochemical studies. The defect structure of the materials was analyzed using photoluminescence spectroscopy, while electron paramagnetic resonance spectroscopy revealed the presence of carbon-based signals related to doping the host material with carbon during synthesis. Specific capacitance measurements indicated that supercapacitors using the C-doped ZnO nanomaterial as electrode materials demonstrated potential for energy-storage applications. Specifically, when tartaric acid was used as a capping agent, the maximal specific capacitance, energy density, and power density values reached 103.1 F/g, 14.3 Wh/kg, and 167 kW/kg, respectively. These results show promise for the development of next-generation supercapacitor devices based on ZnO.