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<p>Dopant engineering offers an effective route to overcome the intrinsic functional limitations of spinel cobalt oxide through controlled defect and electronic modulation. Pure and 5&#xa0;mol% rhenium (Re)-doped Co<sub>3</sub>O<sub>4</sub> nanoparticles were synthesized via scalable wet-chemical precipitation followed by thermal oxidation. X-ray diffraction confirms retention of the cubic spinel structure with subtle lattice distortion and defect generation without secondary phases. Atomic absorption spectroscopy, EDS, and XPS reveal homogeneous dopant distribution, oxygen-vacancy enrichment, high-valence Re species, and mixed Co<sup>2+</sup>/Co<sup>3+</sup> states. Transmission electron microscopy shows ultrasmall nanoparticles (4–10&#xa0;nm) with regulated grain growth. Optical studies indicate defect-mediated electronic transitions with indirect and direct band gaps of ~ 1.65–1.70&#xa0;eV and ~ 2.80–2.90&#xa0;eV. Magnetic measurements demonstrate room-temperature weak ferromagnetism arising from dopant-modified superexchange interactions, enabling effective magnetic hyperthermia. Enhanced surface charge-transfer kinetics further yield rapid, selective, and repeatable NH₃ sensing. These results establish clear structure–property correlations in Re-engineered Co<sub>3</sub>O<sub>4</sub>.</p>

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Sustainable multifunctionality in rhenium-modified CO3O4 spinel: synergistic magnetic activation and high-selectivity NH3 gas sensing

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • P. Vivek

摘要

Dopant engineering offers an effective route to overcome the intrinsic functional limitations of spinel cobalt oxide through controlled defect and electronic modulation. Pure and 5 mol% rhenium (Re)-doped Co3O4 nanoparticles were synthesized via scalable wet-chemical precipitation followed by thermal oxidation. X-ray diffraction confirms retention of the cubic spinel structure with subtle lattice distortion and defect generation without secondary phases. Atomic absorption spectroscopy, EDS, and XPS reveal homogeneous dopant distribution, oxygen-vacancy enrichment, high-valence Re species, and mixed Co2+/Co3+ states. Transmission electron microscopy shows ultrasmall nanoparticles (4–10 nm) with regulated grain growth. Optical studies indicate defect-mediated electronic transitions with indirect and direct band gaps of ~ 1.65–1.70 eV and ~ 2.80–2.90 eV. Magnetic measurements demonstrate room-temperature weak ferromagnetism arising from dopant-modified superexchange interactions, enabling effective magnetic hyperthermia. Enhanced surface charge-transfer kinetics further yield rapid, selective, and repeatable NH₃ sensing. These results establish clear structure–property correlations in Re-engineered Co3O4.