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Defect-engineered rare-earth-doped CuO nanoparticles for advanced symmetric supercapacitors: Experimental and DFT insights
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DOI:10.1016/j.solidstatesciences.2026.108311.png)
Abstract
En 中文
Rare-earth-doped metal oxides hold great promise as high-performance supercapacitor electrodes. In this work, nanostructured Cu1-xEuxO (x = 0.0, 0.01, 0.02, and 0.03) electrode materials were synthesized and systematically investigated through structural, electronic, electrochemical, and DFT analyses. Structural characterization confirms that all samples crystallize in a monoclinic phase and reveals slight lattice distortions and Cu-O bond stretching upon Eu3+ doping. The results demonstrate an increased concentration of oxygen vacancy defects in Eu3+-doped CuO, which likely enhances electrochemical performance by improving conductivity and increasing the density of electrochemically active sites. Compared with pristine CuO and other Cu1-xEuxO compositions, the Cu0.98Eu0.02O electrode exhibits the highest specific capacitance of 1050 F/g at 1 A/g, along with excellent cyclic stability (similar to 93.7%) after 10,000 charge-discharge cycles. Kinetic analysis confirms a diffusion-controlled energy storage mechanism in the Eu3+-doped CuO electrode. Furthermore, the fabricated solid-state symmetric supercapacitor based on Cu0.98Eu0.02O nanoparticles delivers a high energy density of 47.23 Wh/kg at a power density of 674.87 W/kg. DFT calculations of the density of states reveal that the enhanced specific capacitance of Eu3+-doped CuO originates from the localized Eu3+ 4f(6) states near the Fermi level, which contribute to increased quantum capacitance.
Keywords:
Quantum capacitance
Supercapacitors
Eu3+-doped CuO nanoparticles
DFT
XPS
Journal
IF:
3.3
Papers:
6.0K
Citations:
9.2K
