NiO nanosheet-assembled chemiresistive sensor for NO2 detection

Abstract

This paper presents the deposition of nickel oxide (NiO) nanosheets at 0.05, 0.075, 0.1, and 0.125 M solution concentrations by using economical approach of chemical bath deposition (CBD) technique. X-ray diffraction analysis verifies that NiO is polycrystalline with a cubic phase. For NiO film prepared at 0.1 M, FE-SEM and AFM analysis reveals the formation of porous micro-structured morphology of randomly oriented nanosheets and the surface roughness of 62.1 nm, respectively. XPS analysis reveals Ni²⁺ oxidation state in Ni-2p spectra corresponding to the NiO with binding energy peaks at 854.2, 873.1, and 879.8 eV andNi³⁺ at 855.7 and 861.2 eV for Ni₂O₃.NiO nanosheets sensing performance evaluated at sensing conditions of 200 °C to 100 ppm NO₂showed32.2% response with \(\:{\text{T}}_{\text{r}\text{e}\text{s}\text{p}\text{o}\text{n}\text{s}\text{e}}\) = 17 s and \(\:{\text{T}}_{\text{r}\text{e}\text{c}\text{o}\text{v}\text{e}\text{r}\text{y}}\) = 150 s. The results suggest that NiO nanosheets made with the CBD process could be suitable options for commercial NO₂ sensing applications at 200 °C. Finally, NO₂ sensing mechanism of porous NiO microstructure made up of nanosheets is discussed.