School of Material Science & Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China and State Key Lab of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
School of Material Science & Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Analyst. 2021 Jun 14;146(12):4042-4048. doi: 10.1039/d1an00424g.
The trace-level detection of harmful NO2 gas at room-temperature is very important for environmental protection and public health. This paper reports the resonant-gravimetric detection of ppb-level NO2 at room-temperature using two-dimensional porous TiO2 nanosheets (PTNSs) as highly active sensing materials. They are synthesized by a facile high-temperature calcination approach based on a graphene oxide self-sacrificial template. The PTNS sample prepared at 500 °C (TiO2-500 °C) show an anatase structure, while the sample prepared at 800 °C (TiO2-800 °C) contains an impurity rutile phase. By loading pure anatase PTNSs onto resonant microcantilevers, the sensors exhibit high sensitivity to NO2 gas with a limit of detection as low as 15 ppb. Compared with the TiO2-800 °C sample, the much higher sensitivity of the TiO2-500 °C sample can be attributed to the bigger adsorption enthalpy (-ΔH°) of pure anatase TiO2 to NO2 gas molecules (21.7 and 57.8 kJ mol-1, respectively). Density functional theory calculations further demonstrate that the existence of the rutile impurity phase in the TiO2-800 °C sample results in its significantly decreased adsorption activity to NO2. This work approves the great application potential of anatase PTNSs for the highly sensitive resonant-gravimetric detection of NO2 gas at room-temperature.
室温下痕量有害的二氧化氮气体的检测对于环境保护和公众健康非常重要。本文报道了使用二维多孔二氧化钛纳米片（PTNSs）作为高活性传感材料，在室温下对 ppb 级二氧化氮进行共振重力检测。它们是通过基于氧化石墨烯自牺牲模板的简便高温煅烧方法合成的。在 500°C 下制备的 PTNS 样品（TiO2-500°C）呈现锐钛矿结构，而在 800°C 下制备的样品（TiO2-800°C）含有杂质金红石相。通过将纯锐钛矿 PTNS 负载到共振微悬臂梁上，传感器对 NO2 气体表现出高灵敏度，检测限低至 15 ppb。与 TiO2-800°C 样品相比，TiO2-500°C 样品的灵敏度要高得多，这归因于纯锐钛矿 TiO2 对 NO2 气体分子的更大吸附焓（-ΔH°）（分别为 21.7 和 57.8 kJ/mol）。密度泛函理论计算进一步表明，TiO2-800°C 样品中金红石杂质相的存在导致其对 NO2 的吸附活性显著降低。这项工作证明了锐钛矿 PTNSs 在室温下对 NO2 气体进行高灵敏度共振重力检测的巨大应用潜力。
