Low-cost and real-time formaldehyde (HCHO) monitoring is of great importance due to its volatility, extreme toxicity, and ready accessibility. In this work, a low-cost and integrated microelectromechanical system (MEMS) HCHO sensor is developed based on SnO₂ multishell hollow microspheres loaded with a bimetallic PdPt (PdPt/SnO₂-M) sensitizer. The MEMS sensor exhibits a high sensitivity to HCHO ((R_a/R_g – 1) % = 83.7 @ 1 ppm), ultralow detection limit of 50 ppb, and ultrashort response/recovery time (5.0/7.0 s @ 1 ppm). These excellent HCHO sensing properties are attributed to its unique multishell hollow structure with a large and accessible surface, abundant interfaces, suitable mesoporous structure, and synergistic catalytic effects of bimetal PdPt. The well-defined multishell hollow structure also shows fascinating capacities as good hosts for noble metal loading. Therefore, PdPt bimetallic nanoparticles can be employed to construct a synergistic sensitizer with a high content and good dispersity on this multishell hollow structure, further exhibiting a reduced working temperature and ultrasensitive detection of HCHO. This PdPt/SnO₂-M-based MEMS sensor presents a unique and highly sensitive means to detect HCHO, establishing its great promise for potential application in environmental monitoring.

中文翻译：

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负载双金属 PdPt 纳米颗粒的多壳 SnO2 空心微球用于超灵敏和快速甲醛 MEMS 传感器

低成本和实时甲醛 (HCHO) 监测非常重要，因为它具有挥发性、极强的毒性和易于获取的特点。在这项工作中，基于负载双金属 PdPt (PdPt/SnO ₂ -M) 敏化剂的 SnO ₂多壳空心微球开发了一种低成本的集成微机电系统 (MEMS) HCHO 传感器。MEMS 传感器对 HCHO（（R _a / R _g– 1) % = 83.7 @ 1 ppm)、50 ppb 的超低检测限和超短响应/恢复时间 (5.0/7.0 s @ 1 ppm)。这些优异的 HCHO 传感特性归因于其独特的多壳空心结构，具有大而易接近的表面、丰富的界面、合适的介孔结构以及双金属 PdPt 的协同催化作用。定义明确的多壳空心结构也显示出作为贵金属负载良好主体的迷人能力。因此，PdPt双金属纳米粒子可用于在这种多壳空心结构上构建高含量和良好分散性的增效敏化剂，进一步表现出降低的工作温度和对HCHO的超灵敏检测。这种 PdPt/SnO ₂基于 -M 的 MEMS 传感器提供了一种独特且高度灵敏的 HCHO 检测方法，在环境监测中的潜在应用前景广阔。