H2O2-sensing abilities of mixed-metal (Fe-Ni) Prussian blue analogs in a wide pH range

Hydrogen peroxide (H2O2) is generated as a byproduct via enzymatic decomposition reactions of biological molecules; therefore, H2O2 -sensing devices that function in wide pH ranges have been developed. Prussian blue (PB) is one of the most promising materials for constructing electrochemical H2O2-sensing devices; however, PB undergoes hydrolytic decomposition via the N-coordinated Fe(III) of the H2O2-sensing active Fe(II)-CN-Fe(III) moieties even in the weak basic condition of pH 8. In this study, it is anticipated that the homogeneously distributed Ni atoms in the partially Ni-displaced PB analog (Fe-Ni PBA, Fe1-xNix[Fe(CN)(6)](0.67)center dot nH(2)O) effectively block serious structural damage from hydrolytic decomposition. Fe-Ni PBA nanoparticles (NPs) have been successfully prepared in all of the metal composition ratios between x = 0 and 1 and are stably dispersible into water by a surface modification method using [Fe(CN)(6)](4-). The spin-coated thin films composed of the Fe-Ni PBA NPs on ITO substrates function as an electrochemical H2O2 sensor even in the weak basic condition of pH 8, showing a linearity of the catalytic currents within the H2O2 concentrations between 2 x 10(-4) and 5 x 10(-3) mol/dm(3).