Excellent electrocatalytic performance of a Ni2+-loaded multiwalled carbon nanotube composite in glucose oxidation

A new type of Ni2+-loaded MWCNT composite was prepared by mixing carboxylated multiwalled carbon nanotubes (MWCNTs) and Ni2+ ions and allowing them to interact electrostatically. The resulting composite was subsequently used as an electrocatalyst for glucose (Glu) oxidation. Compared with electrodes modified through the addition of free Ni2+ ions or MWCNTs, the Ni2+/MWCNT composite electrode showed greatly improved properties such as hydrophilicity. Investigations of the Ni2+/MWCNT composite electrode via inductively coupled plasma atomic emission spectroscopy and nitrogen adsorption–desorption isotherms verified that Ni2+ ions had been adsorbed onto the surfaces of the MWCNTs in the composite. As expected, a Ni2+/MWCNT composite-based sensor showed extraordinary electrocatalytic performance in Glu oxidation. In the concentration range 0–4.3 mM, a good linear relationship between the Glu added and the current generated was observed, with a correlation coefficient (R 2) of 0.9988. The detection limit and sensitivity were calculated to be 0.081 μM and 2285 μA mM−1 cm−2, respectively. Finally, the new method was successfully applied to determine the Glu in a human blood sample. Recoveries of >100%, indicative of high reliability, accuracy, and precision, were obtained.