Novel reduced graphene oxide/zinc phthalocyanine and reduced graphene oxide/cobalt phthalocyanine hybrids as high sensitivity room temperature volatile organic compound gas sensors

Abstract

In this work, novel 4-pyridynyl-oxadiazole tetrasubstituted zinc and cobalt phthalocyanine compounds were synthesized and characterized by UV-vis, Fluorescence spectroscopy, and SEM. Then these compounds were mixed with reduced graphene oxide. As a result of the interaction of these newly synthesized phthalocyanines with reduced graphene oxide (rGO), rGO/ZnPc and rGO/CoPc hybrids were obtained. The measurement results confirm that the prepared non-covalent rGO/ZnPc and rGO/CoPc hybrid structures are formed by strong π–π interaction. A comparative study of the sensor response of rGO and non-covalently functionalized with zinc and cobalt phthalocyanines (rGO/ZnPc, and rGO/CoPc) hybrids to five different volatile organic compound vapors, ammonia, acetone, ethanol, methanol and butanol is carried out. The response of the sensors increases with respect to ammonia concentrations ranging from 30 to 210 ppm. The response time for 120 ppm ammonia vapor were approximately 250s, 230s and 190s for rGO, rGO/ZnPc, and rGO/CoPc based sensors, respectively. Also, we have conducted selectivity experiments with the aformentioned vapors, thus, studies have indicated that functionalization of rGO with ZnPc results in a 43-fold improvement in sensor response towards ammonia vapors.