Preparation of a Cu2O/rGO porous composite through a double-sacrificial-template method for non-enzymatic glucose detection

We report a double-sacrificial-template method for the fabrication of a Cu2O and a reduced graphene oxide (rGO) porous nanocomposite (Cu2O/rGO), which has great potential in non-enzymatic glucose detection. Firstly, an aqueous graphene oxide (GO) solution was dispersed in a polystyrene (PS)/cyclohexane (CH) solution to prepare a water-in-oil emulsion at 50 °C. Then, the emulsion was cast onto a glass substrate to evaporate solvents and cooled down to room temperature. During that time, the self-assembly of the GO sheets and the PS chains takes place at the interface. The cooling of the emulsion below the θ temperature of the system PS/CH (34.5 °C) facilitates the precipitation of the PS chains at the interface to form microcapsules. A sponge-like PS/GO composite film was thus obtained after complete evaporation of solvents, where the water droplets in the emulsion served as the first sacrificial template. The PS/GO composite was loaded with copper compounds and was then carbonized to remove the second template of the polymer. In this manner, a free-standing porous nanocomposite of Cu2O/rGO was fabricated, and its structure was carefully characterized. The composite was applied as the working electrode in order to take advantages of its porous microstructure, the conductivity of rGO, and the electrochemical performance of crystalline nano-Cu2O. The electrochemical responses of the composite to glucose were evaluated at glucose concentration ranging from 20 to 1000 μM. The results evidence that the porous nanocomposite of Cu2O/rGO exhibits fast and linear amperometric responses to glucose with excellent sensitivities. Moreover, the stability of the Cu2O/rGO composite in the electrolyte solution and its selective response to glucose have been demonstrated to indicate its practical potential.