Defect engineering via oxygen vacancy modulation represents a pivotal strategy in designing high‐performance electrode materials. However, conventional synthetic methods often rely on toxic solvents and multiple postprocessing steps, limiting their scalability and sustainability. Here, we report a facile solvent‐free mechanochemical approach that uses carbon dots (CDs) as oxygen defect engineers in CoMoO 4 (CM) for supercapacitor applications. This one‐step process eliminates solvent usage while enabling precise control over defect formation through CD modulation. The resulting CM‐CDs composite exhibits enhanced electrical conductivity, enlarged specific surface area, and improved electrochemical stability. Optimised electrode delivers an impressive specific capacitance of 603 F g −1 at 1 A g −1 , nearly double that of pristine CM, and retains 87% of its capacitance after 5000 cycles. Furthermore, the assembled asymmetric supercapacitor (CM‐CDs//AC) achieves a remarkable power density of 3995 W kg −1 and maintains 85% capacitance retention after 2700 cycles, demonstrating excellent long‐term durability. Density functional theory (DFT) calculations further reveal that the synergistic effects of heterostructure formation and defect coexistence effectively tune the electronic structure and enhance electrolyte adsorption. This sustainable and economical mechanochemical approach establishes CDs as versatile, green defect‐engineering agents for next‐generation energy materials, providing new insights into the rational design of high‐performance supercapacitor electrodes.
Annamalai et al. (Sun,) studied this question.