Tailored ionically conductive graphene oxide-encased metal ions for ultrasensitive cadaverine sensor

Abstract

Intelligent chemical sensors have been extensively used in food safety and environmental assessment, while limited sensitivity and homogeneity bring about huge obstacles to their practical application. Herein, novel ionically conductive sensitive materials were elaborately designed based on metal ion decorated graphene oxide (GO) via a facile and general in-situ spin-coating strategy, where the abundant functional groups (-OH and -COOH) of GO layer could provide natural binding sites for various bivalent metal cations (such as Cu2+, Ni2+, Zn2+, Co2+, and Mg2+) through coordination and electrostatic interaction. The intercalated metal cations on the layered GO nanosheets can be regarded as charge carriers and complexation with targeted gas (cadaverine, Cad), which is a typical metabolites production and food degradants. By contrast, the designed GO@Cu(II) sensor exhibited the optimal sensing performance toward Cad molecules at room temperature, including ultra-low detection limit (ca. 3 nL), excellent sensitivity, and rapid low concentration detection rate (only 16 s). Interestingly, the sensor exhibited an irreversible and specific response toward Cad, while it showed a transient and reversible response to other interfering gases, implying its outstanding selectivity. In addition, the GO@Cu(II) sensor enabled real-time monitoring of the decay progression of cheese, and it exhibited great potential for large-scale production via its excellent homogeneity. It provides an efficient approach to tailoring intelligent chemical sensors for real-time food safety monitoring and human health warning.