Facile synthesis and high formaldehyde-sensing performance of NiO-SnO2 hybrid nanospheres

A formaldehyde gas sensor with high sensitivity and superior selectivity has been fabricated successfully with NiO-SnO2 hybrid nanospheres, which consisted of n-type porous SnO2 nanospheres and p-type NiO dopants. It has been characterized by X-ray diffraction XRD), high-resolution electron microscopy HRTEM), Scanning Electron Microscopy SEM), X-ray photoelectron spectroscopy XPS), Brunauer-Emmett-Teller BET) and energy-dispersive X-ray spectroscopy EDS). Compared with pure SnO2, the NiO-doped SnO2 nanospheres sensor exhibited significantly enhanced formaldehyde-sensing performances, including lower optimum sensing temperature about 100 degrees C), lower detectable threshold 0.5 ppm), higher sensitivity response = 26.03 to 50 ppm HCHO) and superior selectivity. Based on our experimental results, the role of the addition of NiO and a possible sensing mechanism has also been discussed.