Performance of layer-by-layer deposited low dimensional building blocks of graphene-prussian blue onto graphite screen-printed electrodes as sensors for hydrogen peroxide

Low-dimensional films of graphene oxide (GO)-prussian blue (PB) hybrids were deposited on graphite screen-printed electrodes (SPEs) using a true bottom-up layer-by-layer approach that combines the self-assembly with the Langmuir-Schaefer method. A water dispersion of GO was used as subphase in a Langmuir-Blodgett (LB) deposition system while octadecylamine (ODA), that binds covalently with the GO, was injected at the air-water interface for the formation of an ODA-GO hybrid film onto graphite SPEs through hydrophobic interactions between the latter and the hydrophobic chain of ODA. Then, the outer side of the GO platelets were modified with a second ODA layer (which serves as an anchoring layer to PB through van der Waals attractive forces), immersed in a NaBH sub(4) solution, and finally, the ODA-rGO-ODA layer was brought in contact with an aqueous PB solution. The as-fabricated ODA-rGO-ODA-PB nanostructured sensors were highly reproducible and showed a remarkable electrocatalysis towards reduction of hydrogen peroxide. Inherent limitations as regards the poor working stability of PB-modified sensors were effectively addressed. After an electroless ion-exchanged process in an aqueous solution of 0.1 mol L super(-1) RbCl (or CsCl) for 10 min, the resulting Rb(Cs)-modified assemblies showed an increased sensitivity and working stability, while the working stability was further improved at dimethyldioctadecylammonium-protected assemblies. The developed sensors showed a linear response over the concentration range 5-1000 mu mol L super(-1) H sub(2)O sub(2) and were successfully applied at the amperometric determination of H sub(2)O sub(2) in a mouthwash solution. The detection limit (S/N=3) and the relative standard deviation of the method were 2 mu mol L super(-1) H sub(2)O sub(2) and