Defect rich Ni/NiO-graphene heterostructures with oxygen bridges for enhanced electrocatalytic glucose oxidation towards selective sensing

Abstract

Defect rich Ni/NiO-graphene heterostructures were developed by combining electrocatalytically active Ni/NiO nanocomposite with graphene sheets using a facile single step solution combustion method. The synthesised electrocatalyst was characterized using XRD, Raman, FTIR, XPS, FESEM, TEM and HRTEM techniques. Ni–O–C linkage was evidenced from XPS spectrum in concurrent with G-band shift in Raman spectrum showed the effective integration of active nanocomposite with graphene sheets. Moreover, the wide distribution of active nanocomposite material on graphene sheets with a greater number of defect sites within NiO lattices would expose catalytically active sites for electrochemical redox reaction and synergistic effects of these heterostructures on the electrochemical behaviour of Ni/NiO-GS hybrid nanocomposite employing EIS, CV and CA techniques were discussed. Excellent improvement in the Ni2+/Ni3+ redox activity and enhancement in the glucose oxidative property of Ni/NiO-GS/GCE with respect to Ni/NiO/GCE was contributed to the availability of more electrochemical active surface area and the combined effect of increased mass transport and charge transfer kinetics. The amperometry response of Ni/NiO-GS/GCE towards glucose over a wide linear range (0.5 mM–7.5 mM) with good sensitivity (696 μA mM−1 cm−2) and high correlation coefficient (0.9959) at an applied potential of about 0.495 V vs Ag/AgCl with anti-interference ability, repeatable and reproducible glucose oxidative current responds with an estimated relative standard deviation of 0.018 and 0.014 respectively makes it as a prospective electrode material for cost-effective glucose selective sensor.