Cold plasma assisted synthesis of spinel-CoFe2O4 nanoparticle with narrow bandgap and high magnetic activity

[Display omitted] •A 30-min plasma treatment at 200 °C induced the formation of crystalline particles of inverse spinel CoFe2O4, a phenomenon not observed in samples without plasma treatment.•Plasma treatment at 200 °C, a significant reduction in particle size was observed, with the average size plummeting to 6.7 nm, nearly three times smaller than the calcined sample at 600 °C (24.1 nm).•The plasma assisted synthesized material displayed remarkable magnetic properties, boasting a magnetization (Ms) of 91.80 emu/g and a coercivity (Hc) of 888 Oe. In stark contrast, the material calcined at 600 °C exhibited a lower magnetization of 64.53 emu/g and a higher coercivity of 1289 Oe.•EDX analysis unveiled surface oxygen defects in plasma synthesized material compared to materials synthesized by conventional calcination at 600 °C, resulting in a narrower bandgap (1.9 eV).•XPS analysis unveiled the presence of Co2+ and Co3+ within the spinel crystal structure of the plasma-treated material, elucidating the mechanisms underlying its enhanced magnetic behavior. Non-thermal plasma (NTP)-assisted catalysis offers a promising avenue with diverse applications, particularly in air and water treatment. This study aimed to investigate the utilization of NTP discharge for the synthesis of magnetically active nanoparticles (MANps). We have demonstrated that the NTP discharge-assisted low-temperature calcination effectively induces surface modification and crystallization, thereby enhancing magnetic susceptibility. Specifically, a 30 min plasma treatment at 200 °C (CF-P-200) facilitated the formation of crystalline particles, a phenomenon that was absent in materials synthesized without plasma treatment under similar operating conditions. High-resolution microscopy revealed an average particle size of about 6.7 nm, while EDX analysis unveiled surface oxygen defects in CF-P-200 compared to materials synthesized by conventional calcination at 600 °C (CF-T-600), resulting in a narrower bandgap (1.9 eV). Magnetization measurements conducted using vibrating sample magnetometry (VSM) displayed superior magnetic properties of plasma treated MANps, with a magnetization (Ms) of 91.80 emu/g and coercivity (Hc) of 888 Oe. These values outperformed those of materials calcined at 600 °C (Ms: 64.53 emu/g, Hc: 1289 Oe), emphasizing the efficacy of NTP discharge in enhancing magnetic characteristics during material synthesis.