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

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 ptype 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.

UV-Enhanced Formaldehyde Sensor Using Hollow In2O3@TiO2 Double-Layer Nanospheres at Room Temperature

“…Table compares the sensing performances to HCHO between this work and recent studies on the TiO 2 - or In 2 O 3 -based sensor reported in the literature. Hollow In 2 O 3 /TiO 2 nanocomposites developed herein have a better overall performance with a higher response, a lower operating temperature (RT), a better detection limit, and shorter response/recovery times. ,,,− …”

Nanostructural evolution of hydrothermally grown SrTiO3 perovskite and its implementation in gaseous phase detection of ethanol

“…In figures 7(a)-(d), all the sensors responded in a positive direction of the y-axis unfolding the p-type semiconducting behavior of the SrTiO 3 nanostructures [24]. The p-type conductivity of the SrTiO 3 nanoforms possibly originated from the p-TiO 2 nanoparticles used in hydrothermal synthesis [29]. The higher concentration of Ti vacancy (Ti +4 ) compared to the oxygen vacancy is responsible for the p-type behavior of undoped TiO 2 [29,55,56].…”

“…The p-type conductivity of the SrTiO 3 nanoforms possibly originated from the p-TiO 2 nanoparticles used in hydrothermal synthesis [29]. The higher concentration of Ti vacancy (Ti +4 ) compared to the oxygen vacancy is responsible for the p-type behavior of undoped TiO 2 [29,55,56]. In the transient measurement (figures 7(a)-(d)), ethanol concentration varied from 0.5 to 200 ppm.…”

“…The anatase-TiO 2 solution was synthesized with titanium (IV) isopropoxide (TTIP, 99.99% pure from Sigma Aldrich), acetic acid (CH 3 COOH) and H 2 O by sol-gel method. The detailed procedure of the anatase-TiO 2 synthesis has been discussed in our earlier report [28,29]. Firstly, 25 ml acetic acid was maintained at 0 °C in an ice bath under a steady stirring state.…”

“…The response signal was measured with RM = R v /R a , where R a is the resistance in humid air and R v is the resistance under exposure to the VOC [14,31]. The response time (Tres) and recovery time (Trec) of the sensor are defined as the time required for the resistance to change 90% of the saturation resistance during the adsorption and desorption of VOC [28,29].…”