A mixed-potential sensor with a fugitive carbon-induced porous BaSnO3 sensing electrode for ppb-level N2O detection

Nitrous oxide is a potent greenhouse gas and ozone-depleting substance that requires precise monitoring at trace levels in the atmosphere. This paper reports a high-performance mixed potential sensor based on yttrium-stabilized zirconia (YSZ) electrolyte and BaSnO 3 sensing electrode (SE) for ppb-level N 2 O detection. By introducing a carbon pore-forming agent to regulate the electrode microstructure, a porous mixed conductor BaSnO 3 -SE was successfully fabricated and the sensor performance is significantly enhanced due to extending the triple phase boundary (TPB) length and promoting N 2 O gas diffusion. The experimental results show that compared with BaSnO 3 -SE without carbon additive, the introduction of 10 wt.% carbon into BaSnO 3 -SE leads to the sensitivity increase of the sensor from 29.9 mV/decade to 57.3 mV/decade, while making the detection limit lower from 100 ppb to 25 ppb at 225°C. In addition, the sensor maintains excellent stability over 30 days, exhibits excellent selectivity for common interfering gases and has a predictable oxygen partial pressure dependence. However, humidity greatly interferences the sensor response, which is attributed to higher adsorption energy of H 2 O relative to N 2 O by DFT calculations. The mixed potential response mechanism of the sensor was rigorously confirmed by combining the Tafel curve analysis and mixed potential theoretical derivation. This study proposes a simple and effective electrode structure optimization strategy, which provides an important theoretical and experimental basis for the design of high-precision N 2 O sensors.