Nickel hydroxide modified electrodes for urea determination

Nickel hydroxide films were prepared by electrodeposition from a solution Ni(NO3)2 0,05 mol L ?1 on ITO electrodes (Tin oxide doped with Indium) on PET-like plastic film, applying a current of - 0,1 A cm ?2 during different time intervals between 1800 and 7200 s. The electrochemical behavior of the nickel hydroxide electrode was investigated through a cyclic voltammogram, in NaOH 1,0 mol L ?1, where it was observed two peaks in the profile in 0,410 and 0,280 V, corresponding to redox couple Ni(II)/Ni(III). A sensor for urea presenting a satisfactory answer can be obtained when, after the deposit of the film of Ni(OH)2 on the electrode of nickel, it is immersed in a solution of NaOH 1,0 mol L ?1 and applying a potential of + 0,435 V, where the maximum of the anodic current occurs in the cyclic voltammogram. Analyzing the results it can be observed that, for a range of analite concentration between 5 to 50 m mol L ?1, the behavior is linear and the sensibility found was of 20,3 mA cm?2 (mol L?1)?1, presenting reproducibility confirming the nickel hydroxide electrodes utilization for the determination of urea.