High performance acetaldehyde gas sensor based on p-n heterojunction interface of NiO nanosheets and WO₃ nanorods

P-N heterojunction based chemi-resistive sensor is designed by incorporating NiO nanosheets (NSs) into WO₃ nanorods (NRs) with high aspect ratio. The nanostructured NiO and WO₃ were synthesized by facile hydrothermal chemical route and well-characterized by using XRD, FESEM, EDS, XPS, Raman, and elemental mapping. These two materials mixed in different weight ratio viz 5:95, 15:85, and 25:75 to fabricate the sensors named NW1, NW2, and NW3, respectively. The fabricated sensors were investigated for gas sensing properties at different operating temperatures. All the sensors revealed a high response towards acetaldehyde among various gases at 250 °C. Among these sensors, NW2 exhibited the highest response of 2184 % for 100 ppm acetaldehyde concentration at 250 °C and revealed a high response for 20–100 ppm acetaldehyde range. The NW2 sensor also showed excellent transient resistance response for different concentrations of acetaldehyde gas in real-time. The consistent response of the NW2 sensor for 100 ppm acetaldehyde was dynamically observed and confirmed remarkable repeatability in real-time. The high response and selectivity of the NW2 sensor are due to the p-n heterojunction formed at NiO and WO₃ interface. The hypothesized acetaldehyde sensing mechanism was explored and the stability of the NW2 sensor was tested. This p-n heterojunction-based nanostructure can be promising to design high-performance acetaldehyde sensing application.