Multishell SnO2 Hollow Microspheres Loaded with Bimetal PdPt Nanoparticles for Ultrasensitive and Rapid Formaldehyde MEMSSensors

Low-cost and real-time formaldehyde (HCHO) monitoring is of greatimportance due to its volatility, extreme toxicity, and ready accessibility. In this work, alow-cost and integrated microelectromechanical system (MEMS) HCHO sensor isdeveloped based on SnO2multishell hollow microspheres loaded with a bimetallicPdPt (PdPt/SnO2-M) sensitizer. The MEMS sensor exhibits a high sensitivity toHCHO ((Ra/Rg-1) % = 83.7 @ 1 ppm), ultralow detection limit of 50 ppb, andultrashort response/recovery time (5.0/7.0 s @ 1 ppm). These excellent HCHOsensing properties are attributed to its unique multishell hollow structure with a largeand accessible surface, abundant interfaces, suitable mesoporous structure, andsynergistic catalytic effects of bimetal PdPt. The well-defined multishell hollowstructure also shows fascinating capacities as good hosts for noble metal loading.Therefore, PdPt bimetallic nanoparticles can be employed to construct a synergisticsensitizer 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 sensorpresents a unique and highly sensitive means to detect HCHO, establishing its great promise for potential application in environmental monitoring

Automated summary

This study developed a low-cost and integrated MEMS HCHO sensor based on SnO2 multishell hollow microspheres, exhibiting high sensitivity and an ultralow detection limit. The sensor's excellent performance is attributed to its unique multishell hollow structure and synergistic catalytic effects of bimetal PdPt.