Microwave synthesis of copper catalysts onto reduced graphene oxide sheets for non-enzymatic glucose oxidation

An efficient microwave-assisted synthesis (MS) method to synthesize highly crystalline Cu nanocrystals onto reduced graphene oxide (rGO) sheets for glucose oxidation reaction (GOR) has been investigated. The mass density of Cu nanocrystals onto rGO sheets, ranged from 22.6 to 42.8 wt%, is selected as a controlling factor in determining the catalytic activity toward GOR in alkali electrolyte. The cyclic voltammetry measurement reveals an obvious signature of GOR on the Cu(III)/Cu(II) active surface. Through an appropriate loading of Cu crystals, the Cu-rGO catalysts exhibits an improved performance toward the GOR, including excellent sensitivity, wide detection range, fast response, and superior selectivity. The enhanced performance can be ascribed to a synergetic effect that consists of small crystalline size, uniform dispersion, and two-dimensional conductive support, imparting high accessibility to non-enzymatic catalysis of glucose. Herein the rGO sheets works as a two-dimensional conductive scaffold, capable of rapidly conducting electron and well dispersing Cu nanocrystals. The injection amperometric investigation confirms the highest selectivity of 284 mA g⁻¹ μM⁻¹ is attained, according to a linear regression plot of current response versus glucose concentration, i.e., 0‒1 mM. Accordingly, the robust design of Cu-rGO catalyst electrode can serve as a feasible candidate for non-enzymatic glucose biosensor.