Ni2+ doped cobalt nano-ferrite for gas sensing application

Nickel-doped cobalt ferrite (Ni0.3Co0.7Fe2O4), a transition metal oxide with a spinel structure, is widely used in various industrial applications because of its remarkable properties. In this research, the sol-gel auto-combustion technique was applied, utilizing nitrates, citric acid and double distilled water (DDW) as key components. X-ray diffraction (XRD) analysis confirmed the development of a cubic spinel phase with excellent crystallinity. The crystallite size of the synthesized Ni0.3Co0.7Fe2O4 was found to be 14.3 nm. The porosity of the material, determined from XRD data, is 28.01% which closely matches the 30.01% porosity observed in the scanning electron microscope (SEM) image. SEM and transmission electron microscopy (TEM) observations indicated that the synthesized sample has a spherical shape. Energy dispersive X-ray analysis (EDAX) was used to verify the composition of Ni0.3Co0.7Fe2O4 nanoparticles, confirming that only the essential elements were present in the sample. The selected area electron diffraction (SAED) pattern displayed diffraction fringes that corresponded to the XRD peaks. The band gap was calculated to be 1.74 eV based on UV–Vis spectroscopy. The FTIR spectrum of Ni0.3Co0.7Fe2O4 displays vibrational bands at 558.38 cm−1 and 451.85 cm−1 which are associated with the tetrahedral and octahedral sites, respectively. The vibrating-sample magnetometer (VSM) exhibited an S-shaped hysteresis loop, reflecting the material's magnetic characteristics. In hydrogen gas sensing applications, the material demonstrated a sensitivity of 74 %