Title: Synthesis and characterization of novel CoCr2O4GeO2ZnO core-shell nanostructure: Focus on electrical conductivity and gas sensing properties

Abstract

An effort has been made to develop and synthesize novel CoCr2O4@GeO2@ZnO core-shell nanostructure gas sensor via sol-gel method. The products obtained were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDAX), and Brunaure-Emmet-Teller (BET) analysis. In the present study gas sensing properties of CoCr2O4, CoCr2O4@GeO2 and CoCr2O4@GeO2@ ZnO were studied. The thick films of cobalt chromite and core-shell CoCr2O4@GeO2 and CoCr2O4@GeO2@ZnO were prepared by screen printing technique. The sensing efficiency of these films was checked for various gases including CO, CO2, Cl2, H2, NH3 and H2S. Among these metal oxide-based sensing materials, CoCr2O4@GeO2@ZnO shows highest response at 200 0C for H2S is 627.01, as compared CoCr2O4@GeO2 is 524.01. The pure chromite (CoCr2O4) shows NH3 gas response is 513.21 at 250 0C. The gas response, selectivity, thermal stability and recovery time of sensor is also studied. The humidity dependence of the sensor response for CoCr2O4@GeO2@ZnO was investigated within the test chamber at 100 0C. The statistical analysis data for gas detection is also predicted.