Electrochemical Tuning the Activity of Nickel Nanoparticle and Application in Sensitive Detection of Chemical Oxygen Demand

Nickel nanoparticles were in situ prepared on the surface of glassy carbon electrode via electrochemical reduction using NiSO4 as the precursor. The shape of nickel nanoparticles was successfully controlled by variation of reduction potential, deposition time, pH value, and concentration of Ni2+. The resulting nickel nanoparticles exhibited high activity to the electrochemical oxidation of glycine, and greatly increased the oxidation current of glycine. As a result, the electrochemical activity of nickel nanoparticles toward the oxidation of glycine was easily tuned. The application of nickel nanoparticles in the sensitive and rapid detection of chemical oxygen demand (COD) was studied. Based on the greatly enhanced oxidation current signal of glycine on the surface of nickel nanoparticles, a novel electrochemical method was developed for the detection of COD. The linearity is from 0.24 to 480 mg L-1 and the limit of detection is as low as 0.14 mg L-1. Finally, nickel nanoparticle-modified electrode was used to detect COD values of different water samples, and the results were tested using conventional dichromate method.