A self-regenerable soot sensor with a proton-conductive thin electrolyte and a nanostructured platinum sensing...

In recent years, exhaust sensors have become increasingly attractive for use in energy and environmental technologies. Important issues regarding practical applications of these sensors, especially for soot measurements, include the further development of ion-conductive electrolytes and active electrode catalysts for meeting performance and durability requirements. Herein, we design a proton conductor with a high breakdown voltage and a sensing electrode with high sensitivity to electrochemical carbon oxidation, enabling continuous soot monitoring with self-regeneration of the sensor. A Si_0.97Al_0.03H_xP₂O_7-δ layer with an excellent balance between proton conductivity and voltage endurance was grown on the surface of a Si_0.97Al_0.03O_2-δ substrate by reacting it with liquid H₃PO₄ at 600 °C. Specific reactivity of the electrochemically formed active oxygen toward soot was accomplished by adding a Pt-impregnated Sn_0.9In_0.1H_xP₂O_7-δ catalyst into a Pt sensing electrode. To make the best use of these optimized materials, a unipolar electrochemical device was fabricated by configuring the sensing and counter electrodes on the same surface of the electrolyte layer. The resulting amperometric mode sensor successfully produced a current signal that corresponded to the quantity of soot.