Duan Liangfei, Zhang Yumin, Zhao Jianhong, Zhang Jin, Li Qian, Lu Qingjie, Fu Li, Liu Jing, Liu Qingju
Yunnan Key Laboratory for Micro/Nano Materials & Technology, International Joint Research Center for Optoelectronic and Energy Materials, School of Materials and Energy, Yunnan University, Kunming 650091, China.
CAS Key Laboratory of Cryogenics and Beijing Key Laboratory of Cryo- Biomedical Engineering, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
ACS Appl Mater Interfaces. 2022 Aug 31;14(34):39654-39664. doi: 10.1021/acsami.2c12420. Epub 2022 Aug 18.
Liquid metals (LMs) have emerged as promising functional materials that combine the properties of both liquid and metal. These characteristics enabled them to find applications in many fields. However, the LMs usually can only display a silver-white physical appearance, which limits their further applications in the fields with the imposition of stringent requirements for color and aesthetics. Herein, we report that the surface of LMs was transformed directly from metal to fluorescent semiconductor layer by an example of eutectic GaInSn (eGaInSn) induced by thermal oxidation. Specifically, a core-shell structure is formed from the fluorescent layer and the LMs. The shell endows the LMs with fluorescence without affecting their interior fluidity and conductivity. In particular, the formation process as well as the degree of crystallization, phase transformation, and light emission of the fluorescent oxide shell on the surface of LMs is regulated by the component content. A thorough analysis of surface morphology, composition, structure, and properties of the fluorescent shell suggests that the GaO layer is formed on the surface of gallium-based LMs after their immersion in deionized water. Subsequently, thermal oxidation results in the formation of the β-GaO shell on the surface of liquid metals. Importantly, abundant oxygen vacancies (V) in β-GaO as the donors and the gallium vacancies (V), gallium-oxygen vacancy pairs (V-V), defect energy levels, and intrinsic defects as the acceptors enabled the light emission. The fluorescent LMs have promising potential for flexible lighting and displays, anticounterfeiting measures, sensing, and chameleon robots.
液态金属（LMs）已成为兼具液体和金属特性的有前景的功能材料。这些特性使其在许多领域得到应用。然而，液态金属通常只能呈现银白色外观，这限制了它们在对颜色和美观有严格要求的领域的进一步应用。在此，我们报道通过热氧化诱导的共晶镓铟锡（eGaInSn）实例，液态金属的表面直接从金属转变为荧光半导体层。具体而言，由荧光层和液态金属形成了核壳结构。该壳赋予液态金属荧光特性，同时不影响其内部流动性和导电性。特别地，液态金属表面荧光氧化物壳的形成过程以及结晶程度、相变和发光受组分含量调控。对荧光壳的表面形态、组成、结构和性质的深入分析表明，镓基液态金属浸入去离子水后，其表面形成了GaO层。随后，热氧化导致液态金属表面形成β-GaO壳。重要的是，β-GaO中作为施主的大量氧空位（V）以及作为受主的镓空位（V）、镓-氧空位对（V-V）、缺陷能级和本征缺陷实现了发光。荧光液态金属在柔性照明和显示、防伪措施、传感以及变色龙机器人方面具有广阔的应用潜力。
