Highly sensitive formaldehyde gas sensors based on Ag doped Zn2SnO4/SnO2 hollow nanospheres

Zn2SnO4/SnO2 and Ag doped Zn2SnO4/SnO2 hollow nanospheres were successfully prepared by one-step hydrothermal reaction. Their morphology and element composition were characterized by SEM, TEM, XRD, BET and XPS. Gas sensing performance results show that the Ag doped Zn2SnO4/SnO2 sensor exhibited better performance to 50 ppm formaldehyde including higher response (60) and lower optimum operating temperature (140 °C) compared with pure Zn2SnO4/SnO2. The lowest detectable concentration is 5 ppm. It demonstrated that Ag doping effectively improves the gas sensitive properties to detect low concentration of formaldehyde gas.