Study of nano-Au-assembled amperometric CO gas sensor

A novel electrochemical sensor based on nano-Au colloid modified on Pt disk microelectrode was developed for determination of carbon monoxide (CO). The catalytic activation of nano-Au colloid modified on Pt disk microelectrode as substrate was investigated in different supporting electrolyte solutions by cyclic voltammetry and constant potential transient method. The result shows that nano-Au colloid modified on Pt disk microelectrode exhibited strong catalytic effect toward the electrochemical oxidation of CO in 0.5 mol l−1 HClO4. As compared with the bare Pt disk microelectrode, the nano-Au colloid modified on Pt disk microelectrode can greatly decrease the overpotential and obviously increase the current of CO oxidation. The current-time curve recorded under conditions of constant potential and various CO concentrations suggests that current response depends linearly on CO concentration. A linear equation I (μA) = 0.00917 (μg ml−1) + 0.151 with a correlation coefficient of 0.9938 is obtained over the concentration range 0.756 μg ml−1 at potential +800 mV relative to Ag/AgCl reference electrode. The detection limit is 0.65 μg ml−1 and the relative standard deviation is 5.3% (n = 5) at room temperature.