Enhanced performance of TiNb2O7 electrode-based mixed-potential NH3 sensor: Synergy of surface lewis acidity and morphological engineering

Yttria-stabilized zirconia (YSZ)-based ammonia (NH 3 ) sensors offer high-temperature stability and real-time monitoring capabilities for environmental protection. However, these promising sensors suffer from low sensitivity governed by the sensing electrode (SE), where surface Lewis acidity and microstructural properties regulate the selective adsorption and activation of NH 3 . In this work, TiNb 2 O 7 with exposed Ti 4 + /Nb 5+ Lewis-acidic sites was first employed as the SE for a YSZ-based mixed-potential NH 3 sensor, with its microstructure optimized to enhance sensing performance. The sensor exhibited a superior response of −202.41 mV to 200 ppm NH 3 with a sensitivity of −119.27 mV/decade at 600℃, attributed to the synergy between exposed Ti 4+ /Nb 5+ Lewis-acidic sites and optimized triple-phase boundaries accessibility. Furthermore, the sensor demonstrated high selectivity against common interfering gases (NO, NO 2 , C 3 H 6 , and CH 4 ) and robust stability over 30 days.