Conventional gas sensors work upon changes in mechanical or conductive properties of sensing materials during a chemical process, which may limit availabilities of size miniaturization and design simplification. However, fabrication of miniaturized sensors with superior sensitivities in real-time and label-free probing of chemical reactions or catalytic processes remains highly challenging, in particular with regard to integration of materials into a desired smaller volume without losing the recyclability of sensing properties. Here, we demonstrate a unique bimetallic nanostructure, the Au–Pd–Au core–shell–frame nanobrick, as a promising archetype for fabrication of miniaturized sensors at nanoscale. Upon analysis of the aqueous synthesis, both ex situ and in situ, the formation of Au frames is consistent with selective deposition and aggregation of NaBH₄-reduced Au nanoparticles at the corners and edges of cubic Pd shells, where the {100} surfaces, capped by iodide ions, are growth-limited. By virtue of the thin Pd shell (∼3.5 nm) sandwiched in-between the two Au layers of the core and the frame, the Au–Pd–Au nanobrick yields excellent optical sensitivity in hydrogen gas sensing, leading to a large 13 nm spectral shift of light scattering between Pd and PdH_x. The composite nanostructure with a size of ∼60 nm offers an archetype for miniaturized sensors possessing label-free, real-time, and high-resolution probing abilities and hence paves the way for fabrication of highly efficient nanosensors via sustainable methods.

中文翻译：

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双金属Au-Pd-Au纳米砖的制造作为鲁棒纳米等离子体传感器的原型

常规的气体传感器根据化学过程中感测材料的机械或导电特性的变化而工作，这可能会限制尺寸小型化和简化设计的可用性。然而，在化学反应或催化过程的实时和无标记探测中具有超高灵敏度的微型传感器的制造仍然极具挑战性，特别是在将材料集成到所需的较小体积而又不损失传感特性的可回收性方面。在这里，我们展示了一种独特的双金属纳米结构，即Au-Pd-Au核-壳-框架纳米砖，是制造纳米级微型传感器的有希望的原型。在对水合成进行非原位和原位分析后，在立方Pd壳的角和边缘处的_4-还原Au纳米颗粒，其中受碘离子覆盖的{100}表面受生长限制。由于夹在芯层和框架的两个Au层之间的Pd薄壳（约3.5 nm），Au–Pd–Au纳米砖在氢气感测中具有出色的光学灵敏度，从而产生了13 nm的大光谱Pd和PdH _x之间的光散射位移。尺寸约为60 nm的复合纳米结构为具有无标签，实时和高分辨率探测能力的小型传感器提供了原型，从而为通过可持续方法制造高效纳米传感器铺平了道路。