Enzyme-free electrocatalytic sensing of hydrogen peroxide using a glassy carbon electrode modified with cobalt nanoparticle-decorated tungsten carbide

An efficient non-enzymatic electrochemical sensor for hydrogen peroxide (H2O2) was constructed by modifying a glassy carbon electrode (GCE) with a nanocomposite prepared from cobalt nanoparticle (CoNP) and tungsten carbide (WC). The nanocomposite was prepared at low temperature through a simple technique. Its crystal structure, surface morphology and elemental composition were investigated via X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed the composite to be uniformly distributed and that the CoNP are well attached to the surface of the flake-like WC. Electrochemical studies show that the modified GCE has an improved electrocatalytic activity toward the reduction of H2O2. H2O2 can be selectively detected, best at a working voltage of −0.4 V (vs. Ag/AgCl), with a 6.3 nM detection limit over the wide linear range from 50 nM to 1.0 mM. This surpasses previously reported non-enzymatic H2O2 sensors. The sensor was successfully applied to the determination of H2O2 in contact lens solutions and in spiked serum samples.