Nickel-copper bilayer nanoporous electrode prepared by physical vapor deposition at oblique angles for the non-enzymatic determination of glucose

This work presents a novel bilayer Ni/Cu porous nanostructured film electrode prepared by physical vapor deposition (PVD) in an oblique angle configuration. Scanning electron microscopy (SEM) data revealed that the film, with an approximate thickness of 200 nm, is formed by tilted nanocolumns of around 50 nm of diameter and an inclination of 30° with respect to the surface normal. X ray photoelectron spectroscopy (XPS) data confirmed a bilayer configuration with Cu and Ni located at the top and bottom parts of the film, respectively. A porosity of ca. 45-35% as determined by Rutherford back scattering (RBS) offered a large exposed area and excellent diffusion properties that, combined with a very good catalytic activity, rendered these films excellent electrodes for the quantitative determination of glucose. Under optimized working conditions of detection these electrodes presented a high sensitivity of 2.53 A M−1 cm−2 (R2: 0.999), a limit of detection of 0.23 μM and a time response of ca. 2 s. The sensors did not show any loss of response during a period of 4 months. The selectivity of the sensor was checked against various interferences, including physiological compounds, different sugars and ethanol, in all cases with excellent results. The feasibility of using of this sensor for practical applications was confirmed by successfully determining the glucose content in different commercial beverages.