Ultra thin NiO nanosheets for high performance hydrogen gas sensor device

[Display omitted] •Unstacked & ultra thin 2-D NiO nano sheets synthesis via hydrothermal route.•High response and good selectivity towards H2 gas at 250 °C.•NiO sensor operates in low H2 concentration 10–150 ppm at 250 °C.•NiO sensor exhibits excellent transient gas response and stability.•Understanding of H2 sensing mechanism of p-type NiO sensor. Unstacked two dimensional (2-D) NiO nanosheets are synthesized via easy surfactant-free hydrothermal chemical route. NiO sensor is investigated for high performance and selective hydrogen (H2) gas sensing properties. Structural analysis is carried out using XRD pattern. The morphology of NiO is confirmed by using FESEM and TEM micrographs. Atomic state and elemental composition are analyzed by recording XPS and EDS spectra respectively. NiO sensor exhibited a high gas response of 191% for 150 ppm H2 concentration at 250 °C operating temperature with response time 150 s. The lowest H2 detection is observed at the concentration of 10 ppm having the gas response of 22%. The H2 response of NiO sensor was tested at different operating temperatures as well as gas concentrations. The dynamic gas response and sensor stability were recorded and analyzed. The sensing mechanism of NiO sensor was discussed.