In situ exsolution of PdO nanoparticles from non-stoichiometric LaFePd0.05O3+δ electrode for impedancemetric NO2 sensor

Abstract

Abstract Second phase enhanced sensing electrodes have attracted special attention with respect to the effectively improved sensing performance for the solid electrolyte type gas sensors. Herein, we present a facile exsolution process conjunction with non-stoichiometry of oxide host (LaFePd0.05O3+δ) to prepare PdO nanoparticles (NPs) decorated sensing electrode for impedancemetric NO2 sensor. The as-prepared composite electrode was evaluated using various characterization methods and used to detect NO2 with phase angle (Θ) as response signal. The B site excess of the perovskite effectively promoted the NPs exsolution. Well-dispersed PdO NPs were exsolved after treatment in 10% H2/Ar at 700\u202f°C for 30\u202fmin and then re-oxidization by switching the Ar to Air atmosphere during the cooling process. The sensor with PdO NPs decorated LaFeO3 sensing electrode exhibited excellent Θ sensing performances toward NO2 at 450–550\u202f°C. Compared with the pristine LaFeO3 and LaFePd0.05O3+δ sensing electrodes, the decoration of PdO NPs further enhanced the response signal (ΔΘ) of the sensor accompanied by the improved sensitivity and detection limit due to the improved electro-catalytic activity of the materials. The concept exemplified here may serve in the design and development of more sensing materials with advanced functionality for gas sensors.