There have been many attempts to develop solid-state sensor devices for detecting particulate matter (PM) in diesel exhaust; however, in most of these, the accumulated PM must be burned intermittently to allow subsequent sensing cycles. Here, we report a self-regenerable PM sensor using a proton conductive solid electrolyte and an active working electrode for PM oxidation. The withstanding voltage capability of BaZr0.8Y0.2O3-δ was greatly improved by the growth of a dense Zr1-xYxP2O7 film on the electrolyte surface. The reaction of PM with active oxygen under anodic polarization was further enhanced by the addition of IrO2 to the working electrode. As a result of these combined modifications, when the working electrode was anodically polarized, PM was oxidized to CO2 according to a four-electron reaction (C + 2H2O → CO2 + 4H+ + 4e-) while remaining below the self-ignition temperature. This amperometric sensor successfully produced a current signal corresponding to the quantity of PM in a gas stream at an operating temperature of 300°C. These results demonstrate that the sensor can carry out continuous monitoring of PM concentrations while self-regenerating.
Peiling, L., Oogushi, A., Nakashima, K., Kobayashi, K., Nagao, M., & Hibino, T. (2016). A Sensitive and Self-Regenerable Particulate Matter Sensor with a H 3 PO 4 -Modified BaZr 0.8 Y 0.2 O 3-δ Electrolyte and an IrO 2 -Catalyzed Sensing Electrode . Journal of The Electrochemical Society, 163(14), B761–B767. https://doi.org/10.1149/2.1281614jes