Ni-Co-S/PPy core-shell nanohybrid on nickel foam as a non-enzymatic electrochemical glucose sensor

A nickel-cobalt-sulfide nanosheet (Ni-Co-S NS)/polypyrrole nanowire (PPy NW) core/shell-structured composites on nickel foam (NF) was synthesized by facile electrodeposition processes for electrochemical non-enzymatic glucose sensor. PPy NWs grew on the NF substrate by a potentiostatic deposition method, and then the PPy NWs were further served as skeletons for electrodeposition Ni-Co-S nanosheets. The ternary Ni-Co-S NSs as the shell and PPy NWs as the core on the flexible NF constructed the 3D micro/nano structure. The as-prepared NiCo-S/PPy/NF electrode was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS). The electrochemical sensor was used for the detection of glucose by chronoamperometry. The introduction of the interconnected Ni-Co-S NSs can provide accessible pathways for electrolyte and have high sensitivity to glucose. Compared with the NF and PPy/NF electrodes, the Ni-Co-S/PPy/NF micro/nanohybrid electrode exhibited higher catalytic activity towards electro-oxidation of glucose. The developed Ni-Co-S/PPy/NF electrode showed two linear electrochemical responses to glucose in the range from 2 M to 140 M with a correlation coefficient of R-2 = 0.937 and 0.14 mM to 2 mM with a correlation coefficient R-2 = 0.978, and the detection limit is 0.82 M. Furthermore, the prepared biosensor demonstrated high selectivity to glucose in the presence of uric acid, ascorbic acid and D-fructose.