C60-encapsulated TiO2 nanoparticles for selective and ultrahigh sensitive detection of formaldehyde

Abstract

The current study concerns development of fullerene-C60-encapsulated TiO2 nanoparticles hybrid for an efficient detection of volatile organic compounds (VOCs). The nanocomposite was synthesized via chemical route by using hydrated fullerene-C60 and sol-gel derived undoped p-type TiO2 nanoparticles. The nanocomposite was characterized morphologically and structurally comparing with pure C60 clusters and pure TiO2 nanoparticles as the reference materials. The average diameter of the C60-encapsulated TiO2 nanoparticles was 150 nm whereas the average diameters of C60 clusters and pure TiO2 nanoparticles were 161 nm and 18 nm respectively. Therefore, all the materials were implemented in interdigitated electrode based planner structured sensors and tested towards multiple VOCs. However, C60–TiO2 composite exhibited its natural selectivity towards formaldehyde with a very high sensitivity for the concentration range of 1–1000 ppm. C60-encapsulated TiO2 nanoparticles depicted more than double response magnitude (117%) than the pure TiO2 nanoparticle (48%) and pure C60 particles (40%) and appreciably fast response/recovery (12 s/331 s) towards 100 ppm of formaldehyde at 150 °C. However, the efficient VOC sensing was achieved in C60-encapsulated TiO2 sensors possibly due to the extreme reactive surface provided by the oxygen functionalized C60 and easy electronic exchange between ambient and the TiO2 nanoparticles through C60 layers. The combined properties of both C60 and TiO2 lead to the formation of a promising nanocomposite which provided better sensing characteristics than that of the pure materials.