A novel nano-Au-assembled amperometric SO_2 gas sensor: preparation, characterization and sensing behavior

摘要

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 SO_2 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 x 10~(-3) mol l~(-1) K_3Fe(CN)_6 + 0.10 mol l~(-1) KNO_3, which indicated that the adsorption of Au colloid occurred on the Pt electrodes. Current responses of the nano-Au-assembled gas sensor to SO_2 in different electrolytes, such as 0.1 M HC1, 1 M H_2SO_4, 0.1 M HClO_4 and 1 M NaOH, were investigated with cyclic voltammetry. It was found that the optimal conditions for determining SO_2 were 1 M NaOH as internal electrolyte and +0.6 V as applied potential, while other copresent gases, such as CO, NO, NH_3 and CO_2, 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 x 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 SO_2 under the optimal conditions.