Room temperature methane sensing properties of α-Fe2−xCuxO3 nanoparticles

Abstract

α-Fe_2−xCu_xO₃ (0 ≤ x ≤ 0.17) nanoparticles were synthesized using an improved homogenous co-precipitation method. The effects of doped Cu on crystal structure of α-Fe₂O₃ were investigated by field emission transmission electron microscopy, X-ray diffraction and Raman spectroscopy. Owing to the substitution of Cu²⁺ at the Fe³⁺ sites, the lattice parameters of α-Fe_2−xCu_xO₃ with an average particle size of ∼40 nm and a single corundum structure increased with increasing doped Cu concentration. The shifting of Raman peaks for α-Fe_2−xCu_xO₃ to higher wavenumber was also observed due to the strong electron–phonon interactions and structural distortion after doping Cu. According to the conductivity measurements, doping Cu can increase the concentration of hole carriers and enhance the conductivity of the p-type α-Fe₂O₃ semiconductor. Furthermore, CH₄ sensing characterization showed that the α-Fe_2−xCu_xO₃ nanoparticles are sensitive and have a good selectivity to CH₄ at room temperature, and the response of the material is evidently improved by doping with Cu. The maximum response to 2000 ppm CH₄ at room temperature and 50% relative humidity was obtained when x ≈ 0.10, meeting the common requirements in application. These results suggest that α-Fe_2−xCu_xO₃ nanoparticles can be considered a potential candidate for methane detection at room temperature.