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

Abstract

In order to develop a gas sensitive material with both high sensitivity and good selectivity, Ag–SnO2 MIPs were designed and synthesized by adopting molecular imprinting technique. Specifically, SnO2 nanospheres synthesized through hydrothermal method were used as substrate. Then, Ag–SnO2 was assembled by decorating nano-sized Ag on the surface of SnO2 nanospheres. Molecular imprinting modification with formaldehyde as template molecules was in next conducted to get Ag–SnO2 MIPs. The morphology, valence and crystal structure of the samples were characterized using SEM, XRD, TEM and XPS. The characterization results showed that uniform SnO2 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–SnO2 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–SnO2 MIPs also exhibits high reproducibility and long-term stability.