Narrow Results

Using ionic liquids (ILs) as electrolytes in developing electrochemical sensors for SO₂ detection is of much interest. We compared the electrochemical behaviors of SO₂ in choline chloride–ethylene glycol-based deep eutectic solvent (ChCl–EG-based DES), 1-(3-hydroxypropyl)-3-methylimidazolium tetrafluoroboride ([C₃OHmim]BF₄), and [C₃OHmim]${\text{BF}}_4+$monoethanolamine (MEA) (6.2:1 in molar ratio). Addition of MEA into [C₃OHmim]BF₄ can significantly increase the SO₂ absorption capacity and enhance the electrochemical response of SO₂. However, as we use ChCl–EG-based DES, the reduction current is 10 times larger than in [C₃OHmim]BF₄ and 4 times larger than in [C₃OHmim]${\text{BF}}_4+$MEA (6.2:1 in molar ratio). And SO₂ gas shows high diffusion coefficient value as in the ChCl–EG-based DES. A good linear relationship between the reduction current and the SO₂ content was obtained in the tested SO₂ gas content range from 200ppm to 1500ppm. Our findings provide new route for DESs as electrolytes for SO₂ sensor designing with high sensitivity.