A novel nano-Au-assembled amperometric SO2 gas sensor: preparation, characterization and sensing behavior

In this paper, a novel nano-Au-assembled gas sensor was prepared and characterized with transmission electron microscope (TEM) and electrochemical methods, and its sensing behavior to SO2 was also investigated. Studies showed that when nano-Au particles were assembled on Pt working electrodes, the electrochemical behavior of the Pt electrode was changed in 1.00×10−3 mol l−1 K3Fe(CN)6+0.10 mol l−1 KNO3, which indicated that the adsorption of Au colloid occurred on the Pt electrodes. Current responses of the nano-Au-assembled gas sensor to SO2 in different electrolytes, such as 0.1 M HCl, 1 M H2SO4, 0.1 M HClO4 and 1 M NaOH, were investigated with cyclic voltammetry. It was found that the optimal conditions for determining SO2 were 1 M NaOH as internal electrolyte and +0.6 V as applied potential, while other copresent gases, such as CO, NO, NH3 and CO2, did not cause interference under these conditions. It was also found that the linear scope was from 5 to 500 ppm, the sensitivity was 5.4×10−11 A ppm−1 and the detection limit was 2.6 ppm (S/N) when the nano-Au assembled gas sensor was used to determine SO2 under the optimal conditions.