Characterization of H₂S gas sensor based on CuFe₂O₄nanoparticles

Copper ferrite (CuFe₂O₄) nanoparticles were prepared by the sol-gel auto-combustion method and used to construct a conductometric gas sensor in this work. The as-prepared CuFe₂O₄nanoparticles were annealed at 500 °C and 750 °C. X-ray diffraction measurements as well as transmission electron microscopy were used to identify the crystal structure of as-prepared and annealed nanoparticles. The results reveal growth of nanoparticle size crystal structure as well as phase transition from cubic structure to tetragonal symmetry upon annealing. Fourier Transform Infra-Red Spectroscopy (FTIR) measurements of the CuFe₂O₄nanoparticles revealed the tetrahedral and octahedral absorption bands that are characteristic of the spinel ferrite. Nanoparticle powder was pressed in a form of a pellet to form the gas sensor device. The pellet was placed between a copper sheet and a stainless steel grid for the bottom and top electrodes, respectively. The results revealed that the produced CuFe₂O₄nanoparticles are sensitive to both H₂S and H₂, but with higher sensitivity to H₂S at low temperatures. The gas sensitivity of the sensors could be investigated in terms of the large number of reactive surface sites due to the large surface area of the nanoparticles as well as the adsorption of oxygen species on the surface of nanoparticles.