Construction Of Transition Metal Composite Electrode With Hierarchical Nanostructures And Its Application In Detection Of Glucose With High Sensitivity

Rapid detection of glucose is important in health, food and biotechnology industries, and electrochemical sensor is promising for its small size, low cost as well as fast response. Nanomaterial electrodes show advantages of fast response and high sensitivity in glucose detection, which thanks to high specific surface area and plenty of active defect sites. Traditional methods in making up nano-individuals to macro-electrodes have problems of poor order and low intensity which lead to a twist and even closed mass transfer tunnels. In situ growth of nanostructures on a conductive substrate helps to improve the mass transfer process of objects and electrolytes, the mechanical strength of electrode, and avoid of using adhesives improves the conductivity of nano-individuals. A foamed nickel porous three-dimensional structure (Ni_foam) used as the substrate in this paper, multi-level structures situ grew?load? by Cu, Co metals, metal oxides or hydroxides on the surface of Ni_foam, and the sensitivity of glucose oxidation raised from several mA·mM^-1·cm^-2 in literatures to 10?40 mA·mM^-1·cm^-2.Firstly, elemental copper electrodeposited on Ni_foam in CuSO₄-H₂SO₄ solution, then the prepared Cu treated by high-temperature oxidation at air atmosphere. After the two-step reaction, dense CuO nanowires ?CuO NWs? situ-grew on the surface of Ni_foam, and SEM show the aspect ratio of CuO NWs) up to 500. The electrode in 1 M KOH electrolyte at 0.5 V ?vs. SCE? show a sensitivity of 14.87 mA·cm^-2·mM^-1 to glucose, and the linear range and the detection limit is 1?M-505?M and 0.427?M.Then, nano-dendritic copper ?Cu NDs? and high-density cobalt oxide nanoflakes ?Co?OH?₂ Nfs? situ-electrodepositied on the suface of Ni_foam in the solution of CuSO₄-?NH₄?₂SO₄/CoSO₄-?NH₄?₂SO₄.The two electrodes show 28.58 and 21.08 mA·cm^-2·mM^-1 to 10?M glucose in 0.1 M KOH electrolyte at 0.5 V ?vs. SCE? respectively.Finally, cobalt hydroxide nanosheets and nano-copper particles composite electrode (Co?OH?₂ Nfs/CuNps/Ni_foam) situ-electrodepositied on the suface of Ni_foam by a one-step electrodeposition method in the solution of CuSO₄-CoSO₄-?NH₄?₂SO₄.The characterization of SEM, XPS, TEM to composite electrodes deposited in different time indicating CuNps electrochemical reduction occurs at the initial stage, and then the hydrogen evolution induced Co?OH?₂ Nfs accompanied CuNps reduced occurs.Early deposited CuNps not only help to improve the roughness of substrate, but also improve contact area and firmness of post-load Co?OH?₂ Nfs, as well as the electronic conductivity. Meanwhile, the late co-deposited CuNps further improved the poor conductivity of Co?OH?₂Nfs individuals. The thickness and width of Co?OH?₂ Nfs is 5nm and 600?700 nm which is an excellent load carrier for lately deposited CuNps, and the nanotunnles constructed by staggered nanoflakes benefit to the transformation of glucose and electrolyte molecules, the interpenetration CuNps and Co?OH?₂ Nfs improved the stability of electrodes. Thanks to the synergies between multi-level nanostructures constructed by the metal and hydroxide, Co?OH?₂NFs/CuNps/Ni_foam showed a ultra-sensitivite sensitivity to glucose, the sensitivity up to 42.49 mA·cm^-2·mM^-1?to 10?M glucose?. And the linear rang an detection limit is 1?M-550 ?M and 0.273 ?M. In addition, different batches of Co?OH?₂NFs/CuNps/Ni_foam electrodes had a good parallelism in glucose detection, also showed a resistance to common interferences in blood and peritoneal dialysate ?interference< 5%?, these are demonstrates the non-enzymatic glucose sensor who regarding Co?OH?₂NFs/CuNps/Ni_foam as working electrode will show excellent in glucose detection.