Enhanced titanium carbide MXene structure with CuO quantum dots as an electrode for advanced supercapacitor applications

Abstract

Ti₃C₂ : CuO quantum dot composites with different mass ratios (1 : 0.5, 1 : 1 and 1 : 2) were successfully synthesized through hydrofluoric acid etching of Ti₃AlC₂ (MAX phase) to obtain Ti₃C₂ MXene, followed by sonication-assisted intercalation of quantum dots. The incorporation of CuO quantum dots was found to effectively prevent MXene restacking, enhance ion accessibility, and introduce additional redox-active sites, thereby improving the electrochemical properties of the electrode material. Among the tested composites, the Ti₃C₂ : CuO QDs (1 : 1) composite delivered the highest specific capacitance of 108.1 F g⁻¹ in a three-electrode configuration, significantly outperforming pristine Ti₃C₂ (74.2 F g⁻¹) in 1 M H₂SO₄. An asymmetric supercapacitor (SC) device was further fabricated using Ti₃C₂ : CuO QDs (1 : 1) as the negative electrode and human hair-derived activated carbon as the positive electrode. The device exhibited a high coulombic efficiency of 94.8%, excellent cycling stability with 82.6% capacitance retention after 10 000 cycles, a specific energy of 5.4 W h kg⁻¹, and a power density of 410 W kg⁻¹ at 1 A g⁻¹. These findings highlight the synergistic benefits of CuO quantum dot intercalation and confirm the promise of Ti₃C₂ : CuO QDs composites as advanced electrode materials for high-performance supercapacitors.