The Influence of Charged Interfaces on the Enhanced Photochemical Reactivity of Composites

非技术描述：氢是一种有吸引力的能源生产燃料，因为它具有高能量密度，其燃烧只产生水蒸气，不留下含碳或放射性副产品。然而，与化石燃料或核燃料不同，它不能从地下开采；氢必须被合成。光解或光驱动水分解是一种很有前途的可再生合成氢的方法。然而，目前可用的最佳工艺效率低下，因此无法与传统燃料源竞争。其中一个基本问题是，没有一种材料能同时具备有效分解水所需的各种特性。这个项目是基于这样的想法：一种复合材料，结合了具有协同特性的材料，将能够更有效地催化水的光解作用。技术细节：该项目旨在测试一个假设，即通过控制氧化物异质结构界面上的电荷，有可能建立分离光生电子-空穴对的机制，从而提高光解（水分解）的效率。该项目建立在最近发现的增强光化学反应活性的复合催化剂效应的基础上，其最终目标是开发一种可持续的燃料来源。该假设正在通过研究平面氧化物异质结构（理想的受控测量）和任何实际实施所需的异质结构氧化物粉末的组合来验证。Fe2O3和TiO2薄膜将被支持在各种abo3型衬底上（例如，LaAlO3, SrTiO3, BaTiO3, PbTiO3， BiFeO3和FeTiO3）；通过选择合适的相位和取向，可以控制吸收的光谱范围、载流子类型以及界面上是否存在由铁电性、极性终端产生的电位差。在伪二元cu20 - fe2o3体系中，还将探讨带偏移对化合物的影响。横截面扫描电位（开尔文探针）显微镜被用于绘制埋藏界面的电位差，并将这些测量结果与反应性和效率的光电化学测量结果进行比较。实验还研究了长度尺度对异质结构性能的影响。该研究将成为材料科学与工程专业研究生和本科生教育的重要组成部分。

NON-TECHNICAL DESCRIPTION: Hydrogen is an attractive fuel for energy production because it has a high energy density and its combustion generates only water vapor, leaving no carbon bearing or radioactive by-products. However, unlike fossil or nuclear fuels, it cannot be mined from the earth; hydrogen must be synthesized. Photolysis, or light-driven water-splitting, is a promising renewable method to synthesize hydrogen. However, the best currently available processes are inefficient and, because of this, they are not competitive with conventional fuel sources. One of the fundamental problems is that no single material possesses the combination of properties needed to efficiently split water. This project is based on the idea that a composite, that combines materials with synergistic properties, will be able to catalyze water photolysis more efficiently and currently available materials.TECHNICAL DETAILS: This project aims to test the hypothesis that by controlling charges at interfaces in oxide heterostructures, it is possible to build in mechanisms to separate photogenerated electron-hole pairs and thereby increase the efficiency of photolysis (water-splitting). The project builds upon recent discoveries of the composite catalyst effect for enhanced photochemical reactivity and has the ultimate goal of developing a sustainable fuel source. The hypothesis is being tested by studying a combination of planar oxide heterostructures, ideal for controlled measurements, and heterostructured oxide powders that would be required for any practical implementation. Fe2O3 and TiO2 films will be supported on a variety of ABO3-type substrates (for example, LaAlO3, SrTiO3, BaTiO3, PbTiO3, BiFeO3, and FeTiO3); by choosing the appropriate phase and orientation, it is possible to control the spectral range of absorption, the carrier type, and whether or not there is a potential difference at the interface deriving from ferroelectricity, polar terminations. The effects of band offsets will also be explored in compounds in the pseudo-binary Cu2O-Fe2O3 system. Cross sectional scanning potential (Kelvin probe) microscopy is being used to map potential differences at the buried interfaces and these measurements are being compared to photoelectrochemical measures of reactivity and efficiency. Experiments are also being conducted to examine the effects of length scale on the properties of the heterostructures. The research will be an integral part of the education of graduate and undergraduate Materials Science and Engineering students.