Eco-friendly microplasma fabrication of iron oxide nanoparticles for energy and environmental applications

Rapid energy crisis and dye contamination, due to textile industries, are becoming a global challenge. These energy and environmental challenges are pursuing inexpensive and environmentally friendly nanoparticle fabrication techniques so that efficient supercapacitors and photocatalysts can be generated. In this study, the atmospheric pressure microplasma technique has been used to fabricate iron oxide nanoparticles under various discharge conditions, including 17, 19 and 21 kV at 0.25 M precursor concentration and 1.30 h of treatment time. XRD results revealed a cubic phase of magnetite () along with a crystalline size of 8.5–11 nm. SEM results showed spherical and agglomerated morphology at various discharge conditions. UV and PL results also revealed absorption bands of iron oxide along with high-energy band gap values (3 eV) at 17 kV of discharge voltage. The effects of particle size and lattice strain on the optical properties of iron oxide nanoparticles have also been investigated. Small-sized nanocrystals of iron oxide exhibited excellent specific capacitance of 752 F/g, strong galvanostatic tests of charge–discharge behavior in 3 M KOH solution associated with a high-energy density of 82 Wh/kg and a power density of 2252 W/kg. In addition, as a photocatalyst, iron oxide nanoparticles showed a higher degradation efficiency of 98.1% against methylene blue and of 97.7% against methyl orange in 80 min, with higher values of rate constants, which are great values reported before. The difference in the molecular stability of MB and MO, along with the HOMO–LUMO energy gap in comparison to the VB-CB positions of iron oxide catalyst, has also been illustrated. The boosted electrochemical performance and photocatalytic activity are attributed toward an optimistic electrode material with excellent cyclic stability for potential supercapacitors in future-based energy storage devices, as well as an effective medium for efficient photocatalyst while dealing with environmental hazards.