SnO2 (n)-NiO (p) composite nanowebs: Gas sensing properties and sensing mechanisms

Aiming to optimize SnO2-NiO nanocomposite sensors for detection of hazardous gases, a series of xSnO2-(1-x) NiO composite nanowebs with different compositions (x = 0.1, 0.3, 0.5, 0.7, and 0.9) were synthesized using an electrospinning process. The formation of long and continuous SnO2-NiO nanowebs was verified. Depending on the composition, xSnO2-(1-x) NiO composite nanowebs‎ showed either n-type (SnO2-rich composition) or p-type (NiO-rich composition) gas-sensing behavior. The best sensing performance was obtained for the nanowebs of 0.5SnO2-0.5NiO. The presence of plenty of p-n heterojunctions along with the high oxygen adsorption property of NiO were the main reasons for the high response to the NO2 and C6H6 gases at this optimized composition.