Propene detection at high temperatures using highly sensitive non-nernstian electrochemical sensors based on Nb and Ta oxides

Non-Nernstian electrochemical gas sensors using yttria-stabilized zirconia (YSZ) as an electrolyte offer a simple and inexpensive way of measuring combustion gas emissions at high temperatures. This work reports the development of potentiometric planar sensors for the specific detection of propene at high temperatures. Nb₂O⁵ and Ta₂O⁵ powders were investigated as sensing electrodes due to their unique catalytic properties toward the decomposition of hydrocarbons. Three Pt YSZ metal oxide (MOx) planar electrochemical cells were prepared, based on commercial tape-cast YSZ layers, using Nb₂O⁵, Ta₂O⁵, and a Nb₂O⁵: Ta₂O⁵ mixture in 1:1 weight ratio as MOx sensing electrodes, and their sensing performance was compared. All the sensors showed outstanding responses to 1000 ppm of propene in air and propene sensitivities at 700°C, being -214 mV and -190 mV/dec, respectively, the largest for Ta₂O⁵ electrode-based sensors. However, the sensors using the Nb₂O⁵: Ta₂O⁵ mixture electrode showed the best performance in terms of compromising selectivity and stability with keeping large response and sensitivity values.