electrochemical synthesis of nickel–cobalt oxide nanoparticles on the glassy carbon electrode and its application for the voltammetric determination of 4-nitrophenol

In this article, a new voltammetric sensor for determination of 4-nitrophenol (4-np) based on nickel–cobalt oxide nanoparticle (ni–coox nps)-modified glassy carbon electrode (gce) was presented. the nickel–cobalt nanoparticles (ni–co nps) were firstly electrodeposited on the gce by repetitive potential cycling method, and then, the deposited nps were converted to ni–coox nps by sweeping the potential of the electrode from 0.0 to 0.6 v in 0.1 m naoh solution. the obtained electrocatalyst (ni–coox nps) was analysed via scanning electron microscopy and energy-dispersive x-ray spectroscopy. 4-nitrophenol showed a well-defined reduction peak at about −733 mv at the ni–coox nps/gce in the phosphate buffer solution (ph 6.0). compared with the bare gce, the reduction peak current was clearly enhanced and the overpotential was significantly decreased at the ni–coox nps/gce. the diffusion coefficient (d) of 4-nitrophenol at the modified electrode was also determined utilizing chronoamperometry. the current response of the modified electrode was linear with the 4-np concentration in the range from 7 to 682 µm, with a detection limit of 4.8 µm (s/n = 3), using differential pulse voltammetry.