News Express: UM develops two-dimensional angstrom-porous titania as novel proton-conducting membrane
新聞快訊：澳大成功開發新型超薄多孔質子交換膜
氧化鈦晶體及其表面單原子空位
Schematics of single-Ti-atom vacancies in monolayer titania
澳大成功開發新型超薄多孔質子交換膜
澳門大學應用物理及材料工程研究院助理教授孫鵬展團隊參與開發了一種新型超薄多孔質子交換膜材料，將在燃料電池等氫基技術領域提供耐高溫且兼具高質子傳導率及完美選擇性的新型質子交換膜，解決現有質子交換膜高溫下易脫水失效的問題。相關研究已在國際知名期刊《自然-通訊》（Nature Communications）發表。
二維材料被認為是新一代膜分離技術的候選薄膜材料，與傳統三維材料不同，這些原子級別厚度的薄膜一旦在基面內構建原子級精度的孔道，就能對氣體、液體和各種離子進行超快速、高選擇性的篩選。例如，完美的石墨烯晶體及單層六方氮化硼等少數二維材料對於所有的原子和分子都是不透的，而唯獨質子可以輕鬆穿過。然而，這些材料質子傳導率仍然較低（室溫下<1 S cm-2），無法滿足工業領域的實際需求（>5 S cm-2），同時難以在中高溫區（200-500℃）穩定工作。因此，開發兼具高質子傳導率、完美質子選擇性和中高溫區穩定性的新型二維質子傳導材料具有重要意義。
是次研究以“通過埃級多孔氧化鈦實現高質子傳導率（High proton conductivity through angstrom-porous titania）”為題，開創性地採用埃級多孔氧化鈦二維晶體作為超薄質子交換膜。研究團隊通過層間陽離子交換結合液相剝離法製備氧化鈦二維晶體（圖1，a-b），同時在其表面引入高密度、尺寸分佈均勻的埃尺度原子孔，為高密度原子級孔道的精確構建提供新思路。
是次研究立足於微納器件精密加工及測試技術，深入探索了原子尺度限域條件下不同氣體、離子的跨膜輸運特性。研究發現，該薄膜可完全阻止氦原子通過，並在質子和其他小尺寸離子之間表現出高度的選擇性（圖2，c）。其質子傳導率高達（2.0±0.8 S cm-2），超出石墨烯100倍之多（圖2，d）。同時，該材料在300℃高溫下可以長時間保持結構穩定，質子傳導率隨著溫度的升高呈指數級增長，並在200℃時達到100 S cm-2，比商業化標準質子傳導膜Nafion 117高10倍。此外，該材料可通過逐層靜電組裝等技術實現大規模組裝以形成高品質薄膜，用於工業化大規模應用。
該研究由澳大團隊聯合大連理工大學、英國曼徹斯特大學的團隊共同開發，第一作者為澳大應用物理及材料工程研究院博士後研究員冀宇。該研究得到了澳門大學（檔案編號：SRG2022-00053-IAPME、MYRG-GRG2023-00014-IAPME-UMDF）、國家自然科學基金委員會優秀青年科學基金項目（港澳）（檔案編號：52322319）、澳門特別行政區科學技術發展基金（檔案編號：0063/2023/RIA1）等項目的支援。全文可瀏覽：https://doi.org/10.1038/s41467-024-54544-z
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https://www.um.edu.mo/zh-hant/news-and-press-releases/press-release/detail/60224/
UM develops two-dimensional angstrom-porous titania as novel proton-conducting membrane
A research team led by Sun Pengzhan, assistant professor in the Institute of Applied Physics and Materials Engineering (IAPME) at the University of Macau (UM), participated in the development of a novel two-dimensional proton-conducting material, angstrom-porous titania monolayer. This novel material, designed for hydrogen-based technologies such as fuel cells, offers high temperature resistance, high proton conductivity, and perfect proton selectivity. It addresses the problem of existing proton-exchange membrane being prone to dehydration and failure at high temperatures. The research has been published in the prestigious journal Nature Communications.
Two-dimensional (2D) materials are considered promising candidates for the development of the next generation of membrane technologies. Unlike traditional three-dimensional materials, these atomically thin materials can effectively sieve different gases, liquids, and ions with high flow rates and selectivity. For example, perfect graphene crystals and single-layer hexagonal boron nitride (hBN) are impermeable to all atoms and molecules except protons. However, these 2D materials exhibit low proton conductivity (less than <1 S cm-2 at room temperature), do not meet the requirements of industrial applications (>5 S cm-2) and struggle to maintain stability at intermediate temperatures (200-500°C). Therefore, it is crucial to develop novel 2D proton-conducting materials with high proton conductivity, perfect proton selectivity, and excellent thermal stability.
The research, titled ‘High proton conductivity through angstrom-porous titania’, demonstrates a new approach to precisely fabricate high-density atomic-scale pores across 2D materials. The research team prepared the titania monolayers by delamination of layered bulk titania compound via ion exchange (Fig. 1a, 1b), and negatively charged monovacancies are introduced spontaneously into the basal planes, providing a new route for precise fabrication of high-density angstrom-scale pores.
The research team studied the transmembrane properties of gas and ions under atomic-scale confinement based on the precise fabrication of micro devices. The results show that the angstrom-porous titania crystal is highly permeable to protons but completely impermeable to helium atoms and all other ions (Fig. 2c). It also exhibits a high proton conductivity of about 2.0±0.8 S cm-2, which is 10 times higher than single-layer hBN and 100 times higher than graphene (Fig 2d). Additionally, the material maintained structural stability at high temperatures of 300℃ for extended periods of time, with the proton conductivity increasing exponentially with temperature, reaching 100 S cm-2 at 200°C, which is 10 times higher than the industry standard Nafion 117. Furthermore, the material can be assembled on a large scale using techniques such as layer-by-layer electrostatic assembly to form high-quality membranes for industrial applications.
The research was a collaborative effort between research teams from UM, Dalian University of Technology, and the University of Manchester. The first author of the study is Ji Yu, a postdoctoral researcher at UM IAPME. The research was supported by UM (File No: SRG2022-00053-IAPME, MYRG-GRG2023-00014-IAPME-UMDF), the National Natural Science Foundation of China (File No: 52322319), the Science and Technology Development Fund of the Macao SAR (File No: 0063/2023/RIA1).The full text of the study is available at https://doi.org/10.1038/s41467-024-54544-z.
To read the news on UM’s official website, please visit the following link:
https://www.um.edu.mo/news-and-press-releases/press-release/detail/60224/