Effect of neodymium concentration on the structural and electrochemical properties of hydrothermally synthesized NdCrO3 for supercapacitor applications

초록

Rare-earth-based oxides have emerged as promising electrode materials for high-performance supercapacitors due to their structural stability, tunable electronic configuration, and rich redox activity. In this work, nanostructured NdCrO3 electrodes were synthesized via a hydrothermal method by systematically varying the neodymium precursor concentration (1, 2, and 3 mM) to establish clear structure-property-performance relationships. X-ray diffraction (XRD) with Rietveld refinement confirmed the formation of phase-pure orthorhombic NdCrO3 without secondary phases. X-ray photoelectron spectroscopy (XPS) verified stable Nd3+ and mixed-valence chromium states (Cr3+/Cr4+), indicating abundant redox-active sites. Field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HRTEM) revealed concentration-dependent morphological evolution, where the NdCr-2 sample exhibited a uniformly interconnected nanostructure with enhanced surface accessibility and clear lattice fringes, facilitating rapid ion diffusion and electron transport. Electrochemical measurements showed that the NdCr-2 electrode delivered a high areal capacitance of 7.467 F/cm2 at 2 mA/cm2, with a low equivalent series resistance of 0.36 Ω and reduced charge-transfer resistance. An asymmetric supercapacitor device assembled using NdCr-2 and activated carbon operated within a 0–1.5 V window, achieving an areal capacitance of 674 mF/cm2, an energy density of 0.211 mWh/cm2, and a maximum power density of 10.30 mW/cm2 with 80.77% capacitance retention after 7000 cycles. These results highlight NdCrO3 as a promising electrode material for advanced energy storage applications. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

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