Potentiometric VOC detection at sub-ppm levels based on YSZ electrolyte and platinum electrode covered with gold

A potentiometric oxygen sensor was fabricated and applied to detect several volatile organic compounds (VOCs; acetic acid, methylethylketone, ethanol, benzene, toluene, o- and p-xylene) at sub-ppm levels in the temperature range of 400–500 °C. The half-cell potential of the Pt electrode responded to the sub-ppm levels of VOCs in air. The use of a Pt electrode coated with Au was effective in enhancing the sensitivity. The absolute value of the EMF of the separate-type sensors linearly increased with an increase in the logarithm of VOC concentrations. Both sensing characteristics, a and b, in ΔEMF = a + b log[C] were improved by the modification of the Pt working electrode with Au. For the planar-type sensor with Pt and Au-coated Pt electrodes, the EMF responses in some tenth mV were observed for the examined VOCs at 500 °C.