银-金核-壳纳米立方体的热行为：原位 X 射线衍射和原位电子显微镜（SEM 和 TEM）,The Journal of Physical Chemistry C

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银-金核-壳纳米立方体的热行为：原位 X 射线衍射和原位电子显微镜（SEM 和 TEM）
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2023-09-26 , DOI: 10.1021/acs.jpcc.3c04578
A. Karatzia ₁ , K. Loza ₁ , O. Prymak ₁ , M. Heggen ₂ , M. Epple ₁

Affiliation

通过在银纳米立方体种子表面添加金层来制备银-金核-壳纳米立方体。双金属纳米立方体含有摩尔比为 3:1 的银和金，并通过聚（ N-乙烯基吡咯烷酮）（PVP）稳定。为了阐明它们的热行为，通过原位扫描电子显微镜 (SEM)、原位透射电子显微镜 (TEM) 和原位 X 射线研究了银纳米立方体和银-金核-壳纳米立方体（边长均为 90 nm）粉末衍射 (XRD) 温度高达 1000 °C。纳米立方体在 600 °C 时边缘呈圆形。高于 700 °C，它们在低压条件下（10 ^–5至 10 ^–3Pa) 原位实验。核壳Ag@Au纳米立方体表现出类似的行为，但在400°C以上观察到金扩散到银核中，导致孔隙填充并与银核合金化。银升华后，留下了烧结金。正如对照实验清楚地表明的那样，升华是由于纳米银的蒸气压比微米银或块状银更高。值得注意的是，所有结构变化都发生在远低于银和金的熔化温度（即固态）的情况下。

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Thermal Behavior of Silver–Gold Core–Shell Nanocubes: In Situ X-ray Diffraction and In Situ Electron Microscopy (SEM and TEM)

Silver–gold core–shell nanocubes were prepared by adding a gold layer to the surface of silver nanocube seeds. The bimetallic nanocubes contained silver and gold in a molar ratio of 3:1 and were stabilized by poly(N-vinylpyrrolidon) (PVP). To elucidate their thermal behavior, silver nanocubes and silver–gold core–shell nanocubes (both 90 nm edge length) were studied by in situ scanning electron microscopy (SEM), in situ transmission electron microscopy (TEM), and in situ X-ray powder diffraction (XRD) up to 1000 °C. The nanocubes got rounded edges at 600 °C. Above 700 °C, they started to sublime under the low-pressure conditions (10^–5 to 10^–3 Pa) of the in situ experiments. Core–shell Ag@Au nanocubes showed a similar behavior, but diffusion of gold into the silver core was observed above 400 °C, leading to pore-filling and alloying with the silver core. After the sublimation of silver, sintered gold remained. The sublimation was due to the enhanced vapor pressure of nanoscopic silver in comparison to microscopic silver or bulk silver, as control experiments clearly showed. Notably, all structural changes occurred well below the melting temperatures of silver and gold, i.e., in the solid state.

更新日期：2023-09-26

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