Pt-implanted indium tin oxide electrodes and their amperometric sensor applications for nitrite and hydrogen peroxide

A facile ion implantation method was developed to prepare a novel Pt nanoparticles loaded ITO (PtNPs/ITO) electrode. The resulting nanoparticles were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and electrochemical methods. From the result of electrochemical oxidation of nitrite, we observed that the PtNPs/ITO electrode exhibited excellent electrocatalytic activity, which might be useful in nitrite sensor. The oxidation current of nitrite was linear to its concentration in the range of 5–800 μM and the detection limit (S/N = 3) was down to 0.4 μM. Upon immobilization of the surface of PtNPs/ITO with cytochrome c, Cyt c/PtNPs/ITO for H2O2 biosensor was developed. The characteristics of the biosensor were studied by UV–vis absorption spectra and electrochemical methods. The results revealed that the modified electrode could enhance electron transfer of Cyt c and retain electrochemical activity, good stability and reproducibility. The immobilized Cyt c exhibited a rapid response to H2O2, low detection limit of 0.1 μM and high sensitivity of 37.20 μA mM−1.