Nickel(II)–baicalein complex modified multiwall carbon nanotube paste electrode and its electrocatalytic oxidation toward glycine

A modified electrode, nickel(II)–baicalein complex modified multiwall carbon nanotube paste electrode (Ni(II)–BA–MWCNT–PE), has been fabricated by electrodepositing Ni(II)–BA complex on the surface of MWCNT–PE in alkaline solution. The Ni(II)–BA–MWCNT–PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)–BA–carbon paste electrode (CPE). It also shows better electrocatalytic activity toward the oxidation of glycine than Ni(II)–MWCNT–PE. Kinetic parameters such as the electron transfer coefficient α, rate constant ks of the electrode reaction, the diffusion coefficient D of glycine, and the catalytic rate constant kcat of the catalytic reaction are determined. Moreover, the catalytic currents present linear dependence on the concentration of glycine from 20 μM to 1.0 mM by amperometry. The detection limit and sensitivity are 9.2 μM and 3.92 μA mM−1, respectively. The modified electrode for glycine determination is of the property of simple preparation, fast response, and good stability.