The Ni doped SnO2 has prepared by two-step hydrothermal treatment and followed calcinations.
The gas sensing properties of the Ni doped SnO2 were improved with low Ni-doping concentration (2–4 mol%).
The sensor based on 2 mol% Ni doping SnO2 shows ultrahigh response to n-butanol with good selectivity.
The sensor based on 4 mol% Ni doping SnO2 shows ultrahigh response to formaldehyde.