Dual improvement in sensitivity and selectivity of SnO2 nanospheres for formaldehyde sensing based on molecular imprinting and Ag doping

In order to develop a gas sensitive material with both high sensitivity and good selectivity , Ag–SnO 2 MIPs were designed and synthesized by adopting molecular imprinting technique. Specifically, SnO 2 nanospheres synthesized through hydrothermal method were used as substrate. Then, Ag–SnO 2 was assembled by decorating nano-sized Ag on the surface of SnO 2 nanospheres. Molecular imprinting modification with formaldehyde as template molecules was in next conducted to get Ag–SnO 2 MIPs. The morphology, valence and crystal structure of the samples were characterized using SEM, XRD , TEM and XPS . The characterization results showed that uniform SnO 2 nanospheres were successfully synthesized with metallic Ag distributed on the surface, and the molecular imprinting process did not change the morphology of the material. According to gas sensing measurement results, it was found that the sensor based on Ag–SnO 2 MIPs exhibited superior formaldehyde sensing performance. The molecular imprinting modification effectively improved the sensor's selectivity towards formaldehyde gas. Owning to the catalytic property of Ag, the sensing response of sensor was greatly enhanced. Additionally, Ag–SnO 2 MIPs also exhibits high reproducibility and long-term stability.