CO sensing characteristics of YSZ-based planar sensor using Rh-sensing electrode composed of tetrahedral sub-micron particles

摘要

The nano-structured noble metal sensing electrodes (SEs) were fabricated on a tape-casted yttria-stabilized zirconia (YSZ) substrate by applying the colloidal solution of each of Au, Rh, Ru and Ir, followed by annealing at high temperature. The obtained SEs were studied in YSZ-based planar sensors with respect to a Pt reference-electrode (RE), aimed at obtaining high selectivity and sensitivity to various hazardous gases. As a result, the sensor using 1100 °C-sintered Rh-SE was found to exhibit high CO sensitivity and rather good CO selectivity even at the operating temperature of 700 °C and under highly humid condition (5 vol.% water vapor). SEM observation revealed that Rh-SE was mainly composed of tetrahedral sub-micron particles distributed homogeneously along YSZ substrate. The fabricated sensor was capable of providing stable and repeatable response to each CO concentration in the range of 30-400 ppm and the CO sensitivity varied linearly on the logarithm of gas concentration.