C <sub>60</sub> -encapsulated TiO <sub>2</sub> nanoparticles for selective and ultrahigh sensitive detection of formaldehyde
Teena Gakhar, Arnab Hazra
Abstract
Abstract The current study concerns development of fullerene-C 60 -encapsulated TiO 2 nanoparticles hybrid for an efficient detection of volatile organic compounds (VOCs). The nanocomposite was synthesized via chemical route by using hydrated fullerene-C 60 and sol-gel derived undoped p -type TiO 2 nanoparticles. The nanocomposite was characterized morphologically and structurally comparing with pure C 60 clusters and pure TiO 2 nanoparticles as the reference materials. The average diameter of the C 60 -encapsulated TiO 2 nanoparticles was 150 nm whereas the average diameters of C 60 clusters and pure TiO 2 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, C 60 –TiO 2 composite exhibited its natural selectivity towards formaldehyde with a very high sensitivity for the concentration range of 1–1000 ppm. C 60 -encapsulated TiO 2 nanoparticles depicted more than double response magnitude (117%) than the pure TiO 2 nanoparticle (48%) and pure C 60 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 C 60 -encapsulated TiO 2 sensors possibly due to the extreme reactive surface provided by the oxygen functionalized C 60 and easy electronic exchange between ambient and the TiO 2 nanoparticles through C 60 layers. The combined properties of both C 60 and TiO 2 lead to the formation of a promising nanocomposite which provided better sensing characteristics than that of the pure materials.