Nitrogen-Doped NiO Nanorods Derived from Hydrogen-Bonded Organic Frameworks for Enhanced Triethylamine Gas Sensing: Preparation and Mechanism

Nickel oxide (NiO) is a promising gas-sensing material; however, its gas-sensing performance is often inadequate, such as low response and poor selectivity. Here, we report the successful synthesis of nitrogen-doped NiO (N-doped NiO) nanorods using a novel hydrogen-bonded organic framework (HOF) templating strategy. Compared to undoped NiO nanosheets, the N-doped NiO nanorods exhibit significantly enhanced gas-sensing performance for triethylamine (TEA). Specifically, they demonstrate a 4-fold increase in response to 10 ppm TEA (<i>R</i>_g/<i>R</i>_a = 6.51 and LOD = 10 ppb), good selectivity, remarkably faster response/recovery times (14/11 s), and a lower optimal working temperature of 200 °C. To elucidate the underlying enhancement mechanism, we employ gas chromatography-mass spectrometry (GC-MS) to characterize the gas-sensing reaction in situ. Our findings reveal that NiO facilitates the degradation of TEA into acetaldehyde and ethylenediamine. Crucially, the degradation rate on the surface of the N-doped NiO nanorods is substantially faster than that on the pristine NiO nanosheets. This accelerated degradation is primarily attributed to N-doping-induced modifications of the surface structure of NiO, which consequently promotes the adsorption and catalytic degradation efficiency of TEA. This study introduces a mild and rapid method for preparing uniformly doped, nanostructured N-doped NiO. Furthermore, our in situ quantitative GC-MS analysis provides a robust theoretical basis for understanding the enhanced gas-sensing mechanism of N-doped NiO, offering a valuable foundation for the future development of high-performance N-doped metal-oxide gas sensors.