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^-3mol 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 +0.6V 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.