應用光響應分子和具超高陽離子選擇性及奈米結構之金屬有機框架材料於高效滲透能發電裝置

Abstract

在受到酸鹼值、溫度和光線等外部因素影響的生命過程中，細胞膜中的生物性離子通道在調節離子傳輸方面發揮著至關重要的作用。這些離子通道影響著許多種細胞功能，包括細胞的信號傳導、維持細胞穩定代謝以及細胞內外的物質交換。此外，這些離子通道具有良好的離子選擇性、離子通透性以及離子整流性。而上述這些性質對於生物感測技術、離子分離和能源轉換等多個領域具有顯著的優勢。值得注意的是，光作為一種無所不在的自然能源，在再生能源領域具有極大的發展潛力。近幾年來，科學家們致力於利用各種光響應分子，比如二芳基乙烯、偶氮苯和羥基芘磺酸等，來開發具光響應的仿生性裝置，以期待能在滲透能源領域開創出新的應用前景。在此研究中，我們團隊將UiO-66-(COOH)2的金屬有機框架材料（MOF）填入圓錐形孔道，接著再改質具光響應效果之羥基芘磺酸分子（Pyranine），以此來建構出具光響應的仿生性的離子裝置（Py-MOFMC）。由於UiO-66-(COOH)2 帶有強烈的負表面電荷以及次奈米尺度的孔洞大小（~0.65nm），讓Py-MOFMC 表現出對單價陽離子優異的離子選擇性（Na+/Mg2+的選擇性約為56.7，在照射UV 光後可更進一步提升至70.5），也證實Py-MOFMC 可以作為一種高效率之離子篩選裝置。此外，以此為基礎所製作出的多孔Py-MOFMC裝置在滲透能源發電方面顯示出令人驚豔的功率輸出。500 倍的濃差下，在pH 7的環境中，Py-MOFMC 就可產生20.1 W/m2 的滲透能功率輸出，當pH 值提升至11 時，其功率輸出也可以隨之上升至35.8 W/m2，最後，再進行UV光照的測試後，滲透能功率輸出提升至66.3 W/m2，而這已經遠高於許多已開發出的多孔滲透能源裝置。透過鑑定以及測量，我們成功將MOF材料以及光響應分子結合，開發出具高功率的仿生性裝置，為未來的離子分離技術和滲透能量轉換提供一種全新的研究靈感。

Biological ion channels in cell membranes play a crucial role in processes influenced by external factors such as pH value, temperature, and light. These protein ion channels on cell membranes influence various cellular functions, including cell signaling, maintaining cellular metabolic stability, and the exchange of substances inside and outside the cell. Furthermore, these ion channels exhibit remarkable ion selectivity, permeability, and ion rectification, which provide significant advantages in biosensing, ion separation, and energy conversion. As an omnipresent natural energy source, in recent years, scientists have been dedicated to developing light-responsive artificial ion channel devices by using various light-responsive molecules like diarylethene, azobenzene, and pyranine, aiming to pioneer new applications in the field of osmotic energy. Herein, our team constructed a light-responsive biomimetic ionic device (Py-MOFMC) by embedding UiO-66-(COOH)2 metal-organic framework (MOF) in conical mesochannel (with a tip diameter ~400-500 nm), followed by modification with the light-responsive molecule pyranine. Notably, the negatively charged surface and subnanoscale pore size (~0.65 nm) of UiO-66-(COOH)2 contributed to remarkable selectivity for monovalent cations (with Na+/Mg2+ selectivity ratio of ~56.7, increasing to 70.5 after UV light exposure), indicating its potential as a highly efficient ion filtration device. In addition, the multi-pore Py-MOFMC device also shows excellent power performance. With a salinity gradient of 500-fold and a neutral environment, Py-MOFMC could generate up to 20.1 W/m2 and significantly increase it to 35.8 W/m2 at pH 11. After UV light irradiation, the output could boost to 66.3 W/m2, surpassing many other developed porousosmotic energy devices. Through a series of conceptual validations and studies, we successfully combined MOF materials with light-responsive molecules to develop highi-performance biomimetic devices. This work has opened up new research directions for future ion separation technologies and osmotic energy conversion.