Okada Kenji, Mashita Risa, Fukatsu Arisa, Takahashi Masahide
Department of Materials Science, Graduate School of Engineering, Osaka Metropolitan University Sakai Osaka 599-8531 Japan
JST, PRESTO 4-1-8 Honcho, Kawaguchi Saitama 332-0012 Japan.
Nanoscale Adv. 2023 Feb 9;5(6):1795-1801. doi: 10.1039/d2na00882c. eCollection 2023 Mar 14.
The development of metal-organic framework (MOF) thin films with various functionalities has paved the way for research into a wide variety of applications. MOF-oriented thin films can exhibit anisotropic functionality in the not only out-of-plane but also in-plane directions, making it possible to utilize MOF thin films for more sophisticated applications. However, the functionality of oriented MOF thin films has not been fully exploited, and finding novel anisotropic functionality in oriented MOF thin films should be cultivated. In the present study, we report the first demonstration of polarization-dependent plasmonic heating in a MOF oriented film embedded with Ag nanoparticles (AgNPs), pioneering an anisotropic optical functionality in MOF thin films. Spherical AgNPs exhibit polarization-dependent plasmon-resonance absorption (anisotropic plasmon damping) when incorporated into an anisotropic lattice of MOFs. The anisotropic plasmon resonance results in a polarization-dependent plasmonic heating behavior; the highest elevated temperature was observed in case the polarization of incident light is parallel to the crystallographic axis of the host MOF lattice favorable for the larger plasmon resonance, resulting in polarization-controlled temperature regulation. Such spatially and polarization selective plasmonic heating offered by the use of oriented MOF thin films as a host can pave the way for applications such as efficient reactivation in MOF thin film sensors, partial catalytic reactions in MOF thin film devices, and soft microrobotics in composites with thermo-responsive materials.
具有各种功能的金属有机框架（MOF）薄膜的发展为多种应用的研究铺平了道路。取向的MOF薄膜不仅在面外方向而且在面内方向都可以表现出各向异性功能，这使得MOF薄膜能够用于更复杂的应用。然而，取向MOF薄膜的功能尚未得到充分利用，并且应该培养在取向MOF薄膜中发现新型各向异性功能的能力。在本研究中，我们首次展示了嵌入银纳米颗粒（AgNP）的MOF取向薄膜中与偏振相关的等离子体加热现象，开创了MOF薄膜中的各向异性光学功能。当球形AgNP掺入MOF的各向异性晶格中时，会表现出与偏振相关的等离子体共振吸收（各向异性等离子体阻尼）。这种各向异性等离子体共振导致了与偏振相关的等离子体加热行为；当入射光的偏振平行于主体MOF晶格的结晶轴时，观察到最高的升温，这有利于更大的等离子体共振，从而实现偏振控制的温度调节。使用取向MOF薄膜作为主体所提供的这种空间和偏振选择性等离子体加热可以为MOF薄膜传感器中的有效再激活、MOF薄膜器件中的部分催化反应以及与热响应材料的复合材料中的软微型机器人等应用铺平道路。
