Abstract In the vast majority of early breathing detection, nano-semiconductor gas sensors were widely used due to their high sensing activity and a relatively simple manufacturing process. We developed a simple post-synthetic hydrothermal treatment to fabricate a novel 3-dimensional (3D) structure gas micro-sensor, in which Au modified nanoporous N doped graphene quantum dots (NGQDs)/TiO2 nanospheres were uniformly distributed throughout the graphene foam frameworks. The obtained graphene network-based nanoporous TiO2 gas micro-sensors with a high specific surface area provided a wealth of reaction sites for gas molecular diffusion and improve the response to target gas. The nanocomposites exhibited excellent gas-sensing performance toward ppb-level formaldehyde vapor by contrast gas detection, implying the application prospect in the aspect of breathing detection. More importantly, the graphene foam-based nanocomposites also presented outstanding selectivity and long-term stability. The excellent gas sensing properties were mainly attributed to the combination of NGQDs with TiO2 nanospheres, which indicated that the number of adsorbed oxygen and nano-heterojunction played an important role in enhancing the formaldehyde (HCHO) sensing performance of nanocomposites. Our work has updated a versatile synthesis strategy so that it can be programmed to design a broad series of nanoporous functional composites according to high sensing performance and general adaptability.

中文翻译：

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NGQDs 改性纳米多孔 TiO2/石墨烯泡沫纳米复合材料在高相对湿度下对甲醛具有出色的传感响应

摘要 在绝大多数早期呼吸检测中，纳米半导体气体传感器因其传感活性高、制造工艺相对简单而被广泛应用。我们开发了一种简单的合成后水热处理来制造一种新型的 3D (3D) 结构气体微传感器，其中 Au 修饰的纳米多孔 N 掺杂石墨烯量子点 (NGQDs)/TiO2 纳米球均匀分布在整个石墨烯泡沫框架中。获得的具有高比表面积的基于石墨烯网络的纳米多孔TiO2气体微传感器为气体分子扩散提供了丰富的反应位点，提高了对目标气体的响应。通过对比气体检测，纳米复合材料对 ppb 级甲醛蒸气表现出优异的气敏性能，暗示在呼吸检测方面的应用前景。更重要的是，石墨烯泡沫基纳米复合材料还表现出出色的选择性和长期稳定性。优异的气敏性能主要归功于NGQDs与TiO2纳米球的结合，这表明吸附氧的数量和纳米异质结对提高纳米复合材料的甲醛（HCHO）传感性能起着重要作用。我们的工作更新了一种通用的合成策略，因此可以根据高传感性能和通用适应性对其进行编程以设计一系列广泛的纳米多孔功能复合材料。优异的气敏性能主要归功于NGQDs与TiO2纳米球的结合，这表明吸附氧的数量和纳米异质结对提高纳米复合材料的甲醛（HCHO）传感性能起着重要作用。我们的工作更新了一种通用的合成策略，因此可以根据高传感性能和通用适应性对其进行编程以设计一系列广泛的纳米多孔功能复合材料。优异的气敏性能主要归功于NGQDs与TiO2纳米球的结合，这表明吸附氧的数量和纳米异质结对提高纳米复合材料的甲醛（HCHO）传感性能起着重要作用。我们的工作更新了一种通用的合成策略，因此可以根据高传感性能和通用适应性对其进行编程以设计一系列广泛的纳米多孔功能复合材料。