RESUMEN
Amorphous/crystalline heterophase engineering is emerging as an attractive strategy to adjust the properties and functions of nanomaterials. Here, we reveal a heterophase interface role by precisely tailoring the crystalline Pt coverage density on an amorphous Ru surface (cPt/aRu) for ultrasensitive H2S detection. We found that when the atomic ratio of Pt/Ru increased from 10 to 50%, the loading modes of Pt changed from island coverage (1cPt/aRu) to cross-linkable coverage (3cPt/aRu) and further to dense coverage (5cPt/aRu). The differences in coverage models further regulate the chemical adsorption of H2S on Pt and the electronic transformation process on Ru, which can be proved by ex situ X-ray photoelectron spectroscopy experiments. Notably, a special cross-linkable coverage 3cPt/aRu on ZnO shows the best gas-sensitive performance, in which the operating temperature reduces from 240 to 160 °C compared with pristine ZnO and the selectivity coefficient for H2S gas improves from â¼1.2 to â¼4.6. This is mainly benefit from the maximized exposure of the amorphous/crystalline heterophase interface. Our work thus provides a new platform for future applications of amorphous/crystalline heterogeneous nanostructures in gas sensors and catalysis.
Asunto(s)
Óxido de Zinc , Adsorción , Catálisis , Electrónica , IngenieríaRESUMEN
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 ((Ra/Rg - 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.