College of Sciences, Northeastern University, Shenyang 110819, China.
ACS Sens. 2022 Sep 23;7(9):2750-2758. doi: 10.1021/acssensors.2c01318. Epub 2022 Sep 13.
As a marker molecule in respiratory gases for the pulmonary disease asthma, nitric oxide (NO) has attracted much attention for real-time gas monitoring. However, low sensitivity, poor selectivity, and high operating temperature limit the practical applications of metal oxide semiconductor (MOS) based chemiresistor gas sensors. Herein, by deliberately introducing metal-organic frameworks (MOFs) in free-standing TiO nanochannels (NCs), a chemiresistor gas sensor with excellent detection ability and outstanding selective traits is developed for sensing NO at room temperature (RT). The precisely engineered Cu(II)-based MOF Cu-TCA (HTCA = tricarboxytriphenyl amine) induces more active surface in the NCs, causing the buildup of CuTCA/TiO p-n heterojunctions that improve the sensing response at RT just via a simple UV irradiation (λ = 365 nm). Importantly, the specialized reductive reaction of Cu(II) by NO enables a remarkable selectivity toward NO analysis. Owing to the synergistic large active surface and chemical sensitization effects from Cu-TCA, the resulting Cu-TCA/TiO NCs show outstanding sensing performance; i.e., the response (( - )/) reaches 124% at 50 ppm of NO with a detection limit of 140 ppb at RT. In addition, the response time decreases to 25.6% if the system is subjected to UV irradiation. The as-formed sensing membrane is also demonstrated to be practically effective for flexible and wearable sensing devices for quantitative NO analysis. This study facilitates the use of MOFs to achieve synergistically enhanced selectivity and sensitivity to develop high-performance gas sensors.
作为一种用于肺部疾病哮喘的呼吸气体标记分子，一氧化氮（NO）因其实时气体监测而受到广泛关注。然而，金属氧化物半导体（MOS）基化学电阻气体传感器的灵敏度低、选择性差和工作温度高限制了其实用化。在此，通过在独立的 TiO 纳米通道（NCs）中故意引入金属有机骨架（MOFs），开发了一种在室温下（RT）具有出色检测能力和优异选择性特性的化学电阻气体传感器，用于感测 NO。精确设计的基于 Cu（II）的 MOF Cu-TCA（HTCA=三羧酸三苯胺）在 NCs 中引起更多的活性表面，导致 CuTCA/TiO p-n 异质结的形成，仅通过简单的 UV 照射（λ=365nm）即可提高 RT 下的传感响应。重要的是，NO 对 Cu（II）的专门还原反应使其对 NO 分析具有显著的选择性。由于 Cu-TCA 的协同大活性表面和化学敏化效应，所得的 Cu-TCA/TiO NCs 表现出出色的传感性能；即在 50ppm 的 NO 下，响应（(-)/）达到 124%，RT 下的检测限为 140ppb。此外，如果系统受到 UV 照射，响应时间可缩短至 25.6%。所形成的传感膜还被证明可有效地用于柔性和可穿戴的传感设备，用于定量 NO 分析。本研究促进了 MOFs 的使用，以实现协同增强的选择性和灵敏度，从而开发高性能的气体传感器。
