Altomare Marco, Nguyen Nhat Truong, Schmuki Patrik
Department of Materials Science , Institute for Surface Science and Corrosion WW4-LKO , University of Erlangen-Nuremberg , Martensstraße 7 , D-91058 Erlangen , Germany . Email:
Chemistry Department , Faculty of Sciences , King Abdulaziz University , 80203 Jeddah , Kingdom of Saudi Arabia.
Chem Sci. 2016 Dec 1;7(12):6865-6886. doi: 10.1039/c6sc02555b. Epub 2016 Aug 9.
Formation and dispersion of metal nanoparticles on oxide surfaces in site-specific or even arrayed configuration are key in various technological processes such as catalysis, photonics, electrochemistry and for fabricating electrodes, sensors, memory devices, and magnetic, optical, and plasmonic platforms. A crucial aspect towards an efficient performance of many of these metal/metal oxide arrangements is a reliable fabrication approach. Since the early works on graphoepitaxy in the 70s, solid state dewetting of metal films on patterned surfaces has been much explored and regarded as a most effective tool to form defined arrays of ordered metal particles on a desired substrate. While templated dewetting has been studied in detail, particularly from a mechanistic perspective on lithographically patterned Si surfaces, the resulting outstanding potential of its applications on metal oxide semiconductors, such as titania, has received only limited attention. In this perspective we illustrate how dewetting and particularly templated dewetting can be used to fabricate highly efficient metal/TiO photocatalyst assemblies for green hydrogen evolution. A remarkable advantage is that the synthesis of such photocatalysts is completely based on self-ordering principles: anodic self-organized TiO nanotube arrays that self-align to a highest degree of hexagonal ordering are an ideal topographical substrate for a second self-ordering process, that is, templated-dewetting of sputter-deposited metal thin films. The controllable metal/semiconductor coupling delivers intriguing features and functionalities. We review concepts inherent to dewetting and particularly templated dewetting, and outline a series of effective tools that can be synergistically interlaced to reach fine control with nanoscopic precision over the resulting metal/TiO structures (in terms of high ordering, size distribution, site specific placement, alloy formation) to maximize their photocatalytic efficiency. These processes are easy to scale up and have a high throughput and great potential to be applied to fabricate not only (photo)catalytic materials but also a large palette of other functional nanostructured elements and devices.
在特定位置甚至阵列配置下，金属纳米颗粒在氧化物表面的形成和分散是催化、光子学、电化学等各种技术过程以及制造电极、传感器、存储设备和磁性、光学和等离子体平台的关键。对于许多此类金属/金属氧化物结构的高效性能而言，一个关键方面是可靠的制造方法。自20世纪70年代关于图形外延的早期工作以来，图案化表面上金属薄膜的固态去湿已得到大量研究，并被视为在所需衬底上形成有序金属颗粒定义阵列的最有效工具。虽然模板化去湿已得到详细研究，特别是从光刻图案化硅表面的机理角度，但它在金属氧化物半导体（如二氧化钛）上的巨大应用潜力却受到的关注有限。从这个角度出发，我们阐述了如何利用去湿，特别是模板化去湿来制备用于绿色析氢的高效金属/TiO₂光催化剂组件。一个显著优点是，此类光催化剂的合成完全基于自组装原理：阳极自组织的TiO₂纳米管阵列以最高程度的六边形排列自对准，是第二个自组装过程（即溅射沉积金属薄膜的模板化去湿）的理想地形衬底。可控的金属/半导体耦合带来了有趣的特性和功能。我们回顾了去湿尤其是模板化去湿所固有的概念，并概述了一系列有效的工具，这些工具可以协同交织，以纳米级精度对所得金属/TiO₂结构（在高有序性、尺寸分布、特定位置放置、合金形成方面）进行精细控制，以最大限度地提高其光催化效率。这些过程易于放大，具有高通量，并且不仅有很大潜力应用于制造（光）催化材料，还可用于制造大量其他功能性纳米结构元件和器件。
