Mixed-potential type NO2 sensor based on La10Si6O27 electrolyte and WO3 sensing electrode with different morphologies

• La10Si6O27 is used as electrolyte for a mixed-potential type NO2 sensor.
• Y2O3 is introduced as sintering aid to improve the sinterability of La10Si6O27.
• WO3 with different morphologies is used as sensing electrodes for the NO2 sensor.
• Good sensitivity and anti-interference of the sensor are obtained.

A novel mixed-potential type NO2 sensor was fabricated using La10Si6O27 electrolyte and WO3 sensing electrode (SE). The sinterability of La10Si6O27 was significantly improved by the introduction of Y2O3 as sintering aid. WO3 with different morphologies prepared by the citric acid (CA) assisted hydrothermal method was examined as the sensing electrodes of the mixed-potential type NO2 sensors based on La10Si6O27 electrolyte. The results showed that 6 wt% Y2O3 added La10Si6O27 electrolyte sample could get quite dense at a temperature as low as 1500 °C. The morphologies and phase constituents of WO3 were influenced by the CA content. The sensor showed good response–recovery characteristics. Compared with the sensor based on the irregular WO3 particles or nanorods, the sensor using WO3 nanosheets-SE with hexagonal structure exhibited much higher sensitivity (195.6 mV/decade) to NO2 at 550 °C. The response signals of the sensor were slightly affected by coexistent O2 varying from 5 to 20 vol%.