Electrocatalytic oxidation of hydroxylamine at Ni(II)-morin complex modified carbon nanotube paste electrode

A modified electrode, nickel(II)-morin complex modified multi-wall carbon nanotube paste electrode (Ni(II)-MR-MWCNT-PE), has been fabricated by electrodepositing Ni(II)-MR complex on the surface of MWCNT-PE in alkaline solution. The Ni(II)-MR-MWCNT-PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)-MR complex modified carbon paste electrode (CPE). It also shows better electrocatalytic activity toward the oxidation of hydroxylamine than the Ni(II) modified MWCNT-PE (Ni(II)-MWCNT-PE) and Ni(II)-MR-CPE. Kinetic parameters such as the electron transfer coefficient alpha, rate constant k (s) of the electrode reaction and the catalytic rate constant k (cat) of the catalytic reaction are determined. Moreover, the catalytic currents present linear dependence on the concentration of hydroxylamine from 2.5 x 10(-6) to 4.0 x 10(-4) mol L(-1) by amperometry. The detection limit and sensitivity are 8.0 x 10(-7) mol L(-1) and 56.2 mA L mol(-1), respectively. The modified electrode for hydroxylamine determination is of the property of simple preparation, good stability, fast response and high sensitivity.