Synergistic Y-Doping Strategy To Simultaneously Enhance Sensing Response and Humidity Stability in NiO-Based Triethylamine Sensors

Developing MOS-based chemiresistors with both high gas response and humidity resistance poses challenges, primarily due to the effects of water-induced surface poisoning. To address this issue, Y ions are utilized as a beneficial modifying component on p-type NiO nanofibers for constructing a triethylamine chemiresistor, leading to remarkable improvement in the performance for trace-level measurement (250 ppb). The 3Y-NiO sensor exhibits the best response to triethylamine, which is 20 times that of pure NiO nanofibers. Moreover, the sensor exhibits outstanding selectivity and long-term stability. Notably, the investigation on the influence of humidity reveals that as the content of Y 3+ increases, the sensor exhibits a superior humidity resistance. Both the gas response and baseline resistance of 3Y-NiO and 5Y-NiO sensors remain almost unchanged in various humidity environments (35–80% RH). Owing to the modulation on the surface carrier concentration, the change of active oxygen species, and the hydrophobicity of the NiO surface after Y doping, the outstanding gas sensing performance and antihumidity property toward triethylamine have been simultaneously achieved. The underlying mechanisms of enhanced sensing properties and humidity resistance are analyzed by detailed characterizations and density functional theory (DFT) calculations.