The highly sensitive detection of ppb-level NO at room temperature (RT, 25 °C) remains a challenge hindering the detection of metal oxides due to their chemical inactivity. Herein, a strategy for constructing mixed metal oxides with high specific surface areas and highly active surfaces is proposed. In this work, we synthesized NiO-SnO using the solvothermal and calcination methods with Ni/Sn bimetallic organic frameworks (Ni/Sn-BTC MOFs, BTC: benzene-1,3,5-tricarboxylic) as sacrificial templates. The characterization shows that NiO-SnO has a high porosity (0.343 m/g) and a large specific surface area (74.73 m/g), which can produce abundant permeability pathways for NO, maximize the number of active sites, and enhance the capacity for NO capture. The sensing test results indicate that the NiO-SnO sensor exhibits an excellent sensing response of 693.1% (ΔR/R) to 150 ppb NO, a fast response/recovery time (86.8/29.4 s), a distinct selectivity, a lower detection limit (25 ppb) and good long-term stability at RT and 60% RH (RH: relative humidity). The outstanding sensing performance can be attributed to the microstructure characteristics, oxygen vacancies and p-n heterojunctions formed between NiO and SnO. The current work provides a versatile platform for designing sensitive materials with heterogeneous structures and opens up a new pathway for the development of room temperature gas sensors based on metal oxide.

中文翻译：

---

基于 NiO-SnO2 复合材料的超灵敏 NO2 气体传感器，室温下检测限为亚 ppb

室温（RT，25°C）下 ppb 级 NO 的高灵敏度检测仍然是一个挑战，阻碍了金属氧化物的检测，因为它们具有化学惰性。在此，提出了构建具有高比表面积和高活性表面的混合金属氧化物的策略。在这项工作中，我们以 Ni/Sn 双金属有机骨架（Ni/Sn-BTC MOFs，BTC：苯-1,3,5-三羧酸）为牺牲模板，采用溶剂热和煅烧方法合成了 NiO-SnO。表征表明，NiO-SnO具有高孔隙率（0.343 m/g）和大比表面积（74.73 m/g），可以产生丰富的NO渗透通道，最大限度地增加活性位点数量，增强容量不捕获。传感测试结果表明，NiO-SnO传感器对150 ppb NO表现出693.1%（ΔR/R）的优异传感响应、快速响应/恢复时间（86.8/29.4 s）、明显的选择性、较低的检测限(25 ppb)，在 RT 和 60% RH（RH：相对湿度）下具有良好的长期稳定性。优异的传感性能可归因于NiO和SnO之间形成的微观结构特征、氧空位和pn异质结。目前的工作为设计具有异质结构的敏感材料提供了通用平台，并为基于金属氧化物的室温气体传感器的开发开辟了新途径。