Preparation of rough Pt modified Au electrode by silver staining and galvanic replacement reactions for amperometric and fuel-cell-based sensing of ethanol

This paper presents a new approach for preparing a rough Pt film on an electrodeposited Au modified Au disk electrode (Aupla/Au) by silver staining and galvanic replacement reactions (GRRs), and the modified electrode is used for amperometric and fuel-cell-based sensing of ethanol. Briefly, Ag was stained on Aupla/Au through chemical reduction of AgNO3 by hydroquinone (Ag/Aupla/Au). The GRRs between the stained silver and H2PtCl6 produced size-enlarged nanoparticles containing Pt and AgCl, and electroreduction and ammonia rinse of AgCl could efficiently enhance the porosity to finally obtain the PtGRRx/Aupla/Au electrode, where x denotes the number of silver staining/GRR cycles. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, quartz crystal microbalance and cyclic voltammetry were used to characterize the modified electrode. The PtGRR4/Aupla/Au electrode exhibited a linear anodic amperometric response to ethanol concentration from 0.01 mM to 11.3 mM with a limit of detection (LOD, S/N = 3) of 3 μM, excellent stability and acceptable selectivity, which was used for analysis of ethanol in real Chinese liquor samples with satisfactory results. An ethanol/O2 fuel cell was constructed using two PtGRR4/Aupla/Au electrodes, which showed a self-powered linear voltage response to ethanol concentration from 0.02 to 15.7 mM with a LOD of 15 μM.