Manganese doped nickel oxide as room temperature gas sensor for formaldehyde detection

Abstract

The current investigation dealt with the synthesis of Nickel Oxide (NiO) nanoparticles with excellent surface modification using Manganese (Mn) doping via co-precipitation route alongside varying the sintering temperature. The prepared NiO and Manganese doped NiO (Mn–NiO) were characterized to analyze structural, elemental, morphological, optical and gas sensing studies. The research reveals noticeable sensing characteristics for a variety of volatile organic compounds, exclusively for Formaldehyde (HCHO) gases. The diffraction patterns obtained from X-ray diffraction analysis match up to the face-centred cubic phase of NiO. A redshift in the diffraction angles for Mn–NiO nanostructures compared with pristine NiO proves the presence of Mn ions. The scanning electron microscopy technique depicted NiO holding nanohexagon morphologies while the Mn-doped NiO exhibited sphere-like structures. The electronic states and compositions of the pure and Mn-doped NiO nanomaterials were assessed by X-ray photoelectron spectroscopy which affirms the doping and purity of the NiO and Mn–NiO nanomaterials. Moreover, gas sensor studies of NiO and Mn-doped NiO nanomaterials sintered at various temperatures were tested at room temperatures and different concentrations of the formaldehyde (HCHO) gas. The optimized sintering temperatures for pure NiO and doped NiO nanomaterials based on formaldehyde sensors were 500 °C. For 100 ppm concentration, NiO (300 °C), NiO (500 °C), NiO (700 °C) and Mn–NiO (300 °C), Mn–NiO (500 °C), Mn–NiO (700 °C) gas sensors displayed gas responses of 105.43, 3013.5, 83.43, 793.74, 12593, 4698.1 respectively at room temperature. Hence, Mn-doped NiO nanospheres sintered at 500 °C based formaldehyde sensor displayed appreciable response than sensors based on pure NiO and Mn-doped NiO sintered at 500 °C and 700 °C.