Ag₂₉ nanoclusters loaded ultra-thin porous SnO₂ nanosheets for ppb level isopropanol detection

Although loading noble metal silver (Ag) is one of the strategies to improve the performance of semiconductor metal oxide (SMO) sensors, traditional methods of synthesizing Ag nanoparticles do not effectively allow for control over their size and shape, which limits their gas sensing performance. Fortunately, noble metal nanoclusters (NCs) with well-defined atomic structures can overcome the aforementioned issues. In this study, we present the first successful loading of Ag₂₉ NCs onto ultra-thin porous SnO₂ nanosheets, achieving ppb-level detection of isopropanol (IPA). By optimizing the loading amount of the Ag₂₉ NCs, we systematically research its performance in key parameters such as response value (50 ppm IPA@36.8), optimal working temperature, response/recovery time, reproducibility, selectivity, and other aspects in gas sensors. The outstanding IPA sensing performance can be attributed to the ultra-thin porous nanosheet structure formed under precisely controlled hydrothermal and calcination conditions, the changes in oxygen vacancy and band gap induced by Ag₂₉ NCs loading onto SnO₂, and the heterojunction synergistic effect between Ag₂₉ NCs and SnO₂. This work not only reveals that loading of Ag₂₉ NCs is an ideal tool for improving the performance of SMO gas sensor, but also broadens the field of application of noble metal NCs.