Department of Chemical Engineering, Center for Nano- and Molecular Science and Technology, and Texas Materials Institute, University of Texas at Austin, 1 University CO400, Austin, Texas 78712-0231, USA.
Acc Chem Res. 2012 Mar 20;45(3):434-43. doi: 10.1021/ar200164u. Epub 2011 Oct 21.
Porous, high surface area materials have critical roles in applications including catalysis, photochemistry, and energy storage. In these fields, researchers have demonstrated that the nanometer-scale structure modifies mechanical, optical, and electrical properties of the material, greatly influencing its behavior and performance. Such complex chemical systems can involve several distinct processes occurring in series or parallel. Understanding the influence of size and structure on the properties of these materials requires techniques for producing clean, simple model systems. In the fields of photoelectrochemistry and lithium storage, for example, researchers need to evaluate the effects of changing the electrode structure of a single material or producing electrodes of many different candidate materials while maintaining a distinctly favorable morphology. In this Account, we introduce our studies of the formation and characterization of high surface area, porous thin films synthesized by a process called reactive ballistic deposition (RBD). RBD is a simple method that provides control of the morphology, porosity, and surface area of thin films by manipulating the angle at which a metal-vapor flux impinges on the substrate during deposition. This approach is largely independent of the identity of the deposited material and relies upon limited surface diffusion during synthesis, which enables the formation of kinetically trapped structures. Here, we review our results for the deposition of films from a number of semiconductive materials that are important for applications such as photoelectrochemical water oxidation and lithium ion storage. The use of RBD has enabled us to systematically control individual aspects of both the structure and composition of thin film electrodes in order to probe the effects of each on the performance of the material. We have evaluated the performance of several materials for potential use in these applications and have identified processes that limit their performance. Use of model systems, such as these, for fundamental studies or materials screening processes likely will prove useful in developing new high-performance electrodes.
具有多孔、高表面积的材料在催化、光化学和能量存储等应用中起着关键作用。在这些领域中，研究人员已经证明，纳米级结构可以改变材料的机械、光学和电学性能，极大地影响其行为和性能。这种复杂的化学系统可能涉及几个不同的过程，这些过程可以是串联的，也可以是并联的。了解尺寸和结构对这些材料性能的影响需要采用技术来制备清洁、简单的模型体系。例如，在光电化学和锂离子存储领域，研究人员需要评估改变单一材料的电极结构或制备许多不同候选材料的电极的效果，同时保持明显有利的形态。在本综述中，我们介绍了我们通过一种称为反应性弹道沉积（RBD）的方法合成具有高表面积、多孔薄膜的研究。RBD 是一种简单的方法，通过在沉积过程中控制金属蒸汽射流撞击基底的角度，可以控制薄膜的形态、孔隙率和表面积。这种方法在很大程度上独立于沉积材料的身份，并依赖于合成过程中的有限表面扩散，这使得动力学捕获结构得以形成。在这里，我们回顾了我们在沉积多种半导体材料薄膜方面的研究成果，这些材料对于光电化学水氧化和锂离子存储等应用非常重要。RBD 的使用使我们能够系统地控制薄膜电极的结构和组成的各个方面，以研究它们各自对材料性能的影响。我们已经评估了几种材料在这些应用中的潜在用途，并确定了限制其性能的过程。使用这些模型体系进行基础研究或材料筛选过程可能有助于开发新的高性能电极。
