Characterization of iron hexachloroplatinate films and their electrocatalytic properties with NAD+, hemoglobin and O2

Iron hexachloroplatinate (FePtCl₆) films have been prepared by mixing Fe²⁺ and ${\mathrm{PtCl}}_6^{2-}$ ions in an aqueous KBr solution. The electrochemical quartz crystal microbalance (EQCM), rotating ring-disk electrode, UV–visible absorption spectroscopy, stopped-flow kinetic method and cyclic voltammetry were used to study the deposition and growth mechanism of the iron hexachloroplatinate films. The electrochemical and EQCM properties of the films indicated that a single redox process was confined to the immobilized iron hexachloroplatinate films. The deposition of an iron hexabromoplatinate film occurred when ${\mathrm{Pt}}^{\mathrm{IV}}{\mathrm{Cl}}_6^{2-}$ was electrochemically reduced to ${\mathrm{Pt}}^{\mathrm{II}}{\mathrm{Cl}}_6^{4-}$ and Fe³⁺ to Fe²⁺. In the aqueous KCl, pH 3.0, solution, ${\mathrm{Pt}}^{\mathrm{IV}}{\mathrm{Cl}}_6^{2-}$ was electrochemically reduced to ${\mathrm{Pt}}^{\mathrm{II}}{\mathrm{Cl}}_6^{4-}$ and the Fe²⁺ reacted with the ${\mathrm{Pt}}^{\mathrm{II}}{\mathrm{Cl}}_6^{4-}$ and ${\mathrm{Pt}}^{\mathrm{IV}}{\mathrm{Cl}}_6^{2-}$ species. The electrocatalytic reduction properties of NAD⁺ and hemoglobin were determined using the iron hexachloroplatinate films. The electrocatalytic and electrochemical reactions of NAD⁺ with an iron hexabromoplatinate film were investigated using the rotating ring-disk electrode method. The catalytic current increased with the increase of analyte concentration with slope of 1.6 μA/mM.