Heterogeneous Co₃O₄/Carbon Nanofibers for Low Temperature Triethylamine Detection: Mechanistic Insights by Operando DRIFTS and DFT

Abstract

Metal oxide semiconductors (MOS) have been extensively investigated for the detection of toxic organic amines. However, the high working temperature of metal oxide semiconductors (MOS) remains a challenge that greatly limits their potential in sensor technology. Meanwhile, the sensing mechanism of triethylamine (TEA) has not been fully understood. In this work, the authors report the design of heterogeneous Co3O4/carbon nanofibers (Co3O4/CNFs) and their utilization toward TEA detection at low temperature. With an optimized loading density of Co3O4 nanocrystals, the sensor based on Co3O4/CNFs, which exhibits remarkable response to TEA even at room temperature, delivers the best response of Co3O4/CNFs at 150 °C. Notably, the response of Co3O4/CNFs is three times higher than that of pristine Co3O4. More importantly, they, for the first time, elucidate the TEA sensing mechanism via operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations, revealing that the oxidation of TEA undergoes a two‐step process. This work not only paves the way to design high performance sensing materials, but also contributes to the fundamental understanding of a sensing mechanism.

MoO3 Nanorods Decorated by PbMoO4 Nanoparticles for Enhanced Trimethylamine Sensing Performances at Low Working Temperature

“…11,12 Although those reported MoO 3 -based sensors are sensitive to TMA, 12−14 the working temperature is high (300−400 °C), which not only causes a high energy consumption but also brings great inconvenience to the manufacture. 15 In the past few decades, many strategies such as loading noble metals, 16 forming a heterostructure with metal oxides, 17 combining with carbon materials, 18 enriching oxygen vacancies, 19 etc., have been used to enhance the gas sensing performance of metal oxide-based sensors. Therein, the heterostructure formation strategy has made remarkable progress in improving sensing performance owing to the enhanced electron transfer and increased chemisorbed oxygen ions.…”

“…Over the past few decades, gas sensors, especially those based on unary metal oxides such as ZnO, CuO, WO 3 , NiO, MoO 3 , etc., have attracted great attention due to their high sensitivity, excellent reusability, facile fabrication process, etc. , Among these metal oxides, MoO 3 -based sensors have been widely applied in TMA sensing, mainly attributed to their strong absorption of TMA and abundant Lewis acid sites that are reactive with basic TMA. , Although those reported MoO 3 -based sensors are sensitive to TMA, − the working temperature is high (300–400 °C), which not only causes a high energy consumption but also brings great inconvenience to the manufacture …”

Humidity-Tolerant Chemiresistive Gas Sensors Based on Hydrophobic CeO2/SnO2 Heterostructure Films

“…The intermediate products would then react with the O − species, releasing electrons back to the MOS surface. 48 → O (gas) O (…”

“…Besides, the TEA molecules adsorbed on the MOS surface may be first decomposed into intermediate products such as C 2 H 4 and NH 3 . The intermediate products would then react with the O – species, releasing electrons back to the MOS surface …”

Recent Progress on Flexible Room-Temperature Gas Sensors Based on Metal Oxide Semiconductor

“…CNTs is a widely used carbon-based material for gas sensing owing to its high specific surface area, fabulous electrical conductivity, and great flexibility characteristics [ 203 ]. In addition, CNTs provide an effective conductive pathway for electron transport, further improving the response value and response rate of the CNTs/MOS sensors [ 204 ]. Single-walled carbon nanotubes (SWCNTs) are cylindrical nanotubes rolled up by honeycomb lattice carbon sheets.…”