Conventional colloidal syntheses typically produce nanostructures with positive curvatures due to thermodynamic preference. Here, we demonstrate the creation of surface concavity in Au nanorods through seed-mediated growth in confined spaces and report their thermochromic responses to temperature changes. The unique surface concavity is created by templating against Fe₃O₄ nanorods, producing a new concavity-sensitive plasmonic band. Due to the high surface energy, the metastable nanorods can be reconstructed at a moderate temperature, enabling convenient and precise tuning of their plasmonic properties by aging in different solvents. Such structural reconstruction of concave Au nanorods enables the fabrication of thermochromic plasmonic films that can display images with vivid color changes or exhibit encrypted, invisible information upon aging. This templating strategy is universal in creating concave nanostructures, which may open the door to designing new nanostructures with promising applications in sensing, anticounterfeiting, information encryption, and displays.

中文翻译：

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具有表面凹陷的热致变色金纳米棒的创建和重建

由于热力学偏好，传统的胶体合成通常会产生具有正曲率的纳米结构。在这里，我们展示了通过种子介导在密闭空间中的生长在 Au 纳米棒中产生表面凹度，并报告它们对温度变化的热致变色反应。独特的表面凹度是通过对 Fe ₃ O ₄进行模板化而产生的纳米棒，产生一个新的凹敏感等离子体带。由于高表面能，亚稳态纳米棒可以在适中的温度下重建，通过在不同溶剂中老化能够方便和精确地调整其等离子体特性。凹金纳米棒的这种结构重建能够制造热致变色等离子体薄膜，该薄膜可以显示具有生动颜色变化的图像或在老化时显示加密的不可见信息。这种模板策略在创建凹面纳米结构方面具有普遍性，这可能为设计在传感、防伪、信息加密和显示方面具有广阔应用前景的新型纳米结构打开大门。