A Sensitive and Self-Regenerable Particulate Matter Sensor with a H₃PO₄-Modified BaZr_0.8Y_0.2O_3-δElectrolyte and an IrO₂-Catalyzed Sensing Electrode

Abstract

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 selfregenerable PM sensor using a proton conductive solid electrolyte and an active working electrode for PM oxidation. The withstanding voltage capability of BaZr 0.8 Y 0.2 O 3-δ was greatly improved by the growth of a dense Zr 1-x Y x P 2 O 7 film on the electrolyte surface. The reaction of PM with active oxygen under anodic polarization was further enhanced by the addition of IrO 2 to the working electrode. As a result of these combined modifications, when the working electrode was anodically polarized, PM was oxidized to CO 2 according to a four-electron reaction (C + 2H 2 O → CO 2 + 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.