Morphological Control of Cobalt Ferrite Using Ionic Liquids for Enhanced Optical and Electrocatalytic Properties
DOI:
https://doi.org/10.48048/tis.2026.14859Keywords:
Cobalt ferrite, Ionic liquid, Soft templates, Morphology, Optical properties, Electrocatalysis, Oxygen evolution reactionAbstract
The morphology of cobalt ferrite (CoFe2O4) plays a crucial role in governing optoelectronic and catalytic properties by influencing electron transport and surface reactivity. In this work, CoFe2O4 was synthesized with varying morphology using an ionic liquid (IL)-assisted hydrothermal method from iron(III) nitrate nonahydrate and cobalt(II) nitrate hexahydrate. Two ILs, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([C2mim]CF3SO3) and 1-ethyl-3-methylimidazolium methanesulfonate ([C2mim]CH3SO3), which share a common cation but differ in physicochemical properties, were used as soft templates to tailor morphology. Formation of CoFe2O4 and removal of IL were confirmed using Fourier transform infrared (FTIR) and energy-dispersive X-ray (EDX) spectroscopic techniques. IL modified the particle shape from a nanocube to a nanosphere and played a decisive role in controlling particle size through growth modifications. Five times smaller particles (17 nm) compared to native CoFe2O4 (84 nm) were obtained using ILs. A narrower size distribution, with smaller hydrodynamic diameters, was observed for ILs, as shown by dynamic light scattering (DLS) analysis. Highly crystalline, pure face-centered cubic (FCC) spinel structures were obtained using [C2mim]CH3SO3. The optical band gap energy of CoFe2O4 was reduced from 1.93 to 1.83 eV in the presence of [C2mim]CH3SO3 due to changes in cationic distribution and charge transfer induced by the IL. A low onset overpotential of 303 mV in 1.0 M KOH was observed in CoFe2O4 synthesized using [C2mim]CH3SO3, indicating enhancement of electrocatalytic properties due to a higher number of active sites, smaller particles, and exposed facets. However, the lowest Tafel slope of 103 mV dec−1 was obtained for [C2mim]CF3SO3 due to the faster kinetics on the electronically modified surface induced by fluorine-based anion. In IL-assisted CoFe2O4, the predominant (111) facet and modified surface structure might be responsible for improved performance in the oxygen evolution reaction (OER). This study demonstrates the tunability of optical and electrocatalytic properties of CoFe2O4 by controlling growth and formation of NPs using ILs.
HIGHLIGHTS
- Tuning morphology of cobalt ferrite magnetic nanoparticles using ionic liquids as soft templates
- Ionic liquids having a common cation and different anions
- Soft templating actions of 1-ethyl-3-methylimidazolium trifluoromethanesulphonate ([C2mim]CF3SO3) and 1-ethyl-3-methylimidazolium methanesulphonate ([C2mim]CH3SO3)
- Improving electrocatalytic and optical behavior of cobalt ferrite by controlling morphology via growth modifications
GRAPHICAL ABSTRACT
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