| 초록 |
Sub-ppm hydrogen (H2) gas sensing in real environments is an essential aspect of the hydrogen economy pathway. However, the humidity tolerant the gas sensing response and performance of H2 sensors in real-life application. It is well known that the gas sensing characteristics of semiconductor oxide can be improved significantly by altering the compositional and morphological design of the nanostructures. In terms of composition and morphology, yolk-shell nanoparticles have attracted more attention for chemiresistive gas sensors because of their high surface area to volume ratio, high gas accessibility, tunable composition, and effective electron depletion. In this study, we design a novel Au-Ag/SnO2-CeO2 yolk-shell nanostructures for humidity-independent sub-ppm H2 sensing. Firstly, we synthesized the Ag sub-micron-sphere (~1 µm) through the citrate method followed by SnO2 coating to make the core-shell structure. Using galvanic replacement reaction, the core-shell structure was converted to the Au-Ag alloy- SnO2 yolk-shell structures. Then, ultrasmall CeO2 nanoparticles (＜ 5 nm) were decorated on the Au-Ag alloy- SnO2 yolk-shell nanostructures. To study the effect of compositional and morphological on gas sensing, their chemiresistive sub-ppm H2 sensing behaviors were investigated in dry and wet atmospheres at low temperatures (150°C). The fabricated yolk-shell sensor showed similar sensor resistance and gas response in dry and highly humid (RH 10-90%) atmospheres. Also, this sensor exhibited a high response and good selectivity for sub-ppm H2 sensing. The water vapor on the surface of yolk-shell nanostructures interacts with Ce3+/Ce4+ redox pair while Au-Ag alloy- SnO2 improves the H2 sensing performance. |
