Semiconductor/Mixed-Conducting-Oxide Heterojunction for Photo-electrochemical H2O & CO2 Splitting at Elevated Temperatures

建议编号：1336835机构：斯坦福大学标题：半导体/混合导电氧化物异质结用于高温下光电化学分解H2O和CO2使太阳能在需要的时候随时随地可用对于提高太阳能的利用率至关重要。将蒸汽和/或二氧化碳分解成化学燃料是储存太阳能的一条很有前途的途径。这项工作的目标是设计一种工作在500到700℃的新型光电化学电池。而不是在室温下使用全固态设计。利用由半导体吸光体和氧离子和电子混合导电氧化物组成的氧化物异质结，入射太阳能在吸光体带隙上方和下方被转化为热能，这反过来又提高了太阳能到燃料的效率。与传统的基于光伏的方法不同，这里的太阳能对燃料的效率随着温度的升高而增加，而不是降低。由铁、钒和钛氧化物等氧化物组成的薄膜异质结将被评估其在高温光电化学水和二氧化碳分解方面的潜力。这项研究的具体目标是确定一种能够在数千小时内提供高太阳能燃料转换效率和可靠性的材料组合。这项研究的中心组成部分是了解和控制半导体氧化物和混合离子和电子导电氧化物之间异质结处的电荷产生、分离和复合，温度显著高于环境温度。在涉及氧化物的光电化学中，离子缺陷(如空位)肯定起着重要的作用，但人们对它的认识还不够深入。通过快速材料筛选、光电化学和原位同步辐射X射线表征氧化物异质结，本研究旨在了解极端条件下不同固体间的界面化学和电学性质，旨在提高间歇性太阳能以化学键存储的可行性，提高太阳能的全球利用率。除了能源的产生和储存，对异质结电荷传输的深入了解将有助于催化和高温电子等科学领域，以及极端环境中的固体氧化物燃料电池和传感器等应用。项目工作还为一名研究生在项目期间提供了研究机会。除了将结果纳入本科生和研究生的课程之外，PI还将开发一个独特的“天黑后的太阳”推广计划。人类与阳光的互动是日常生活中最普遍的现象之一，也是提高学生对科学和工程兴趣的极好工具。

PI: Chueh, WilliamProposal Number: 1336835Institution: Stanford UniversityTitle: Semiconductor/Mixed-Conducting-Oxide Heterojunction for Photo-electrochemical H2O and CO2 Splitting at Elevated TemperaturesMaking solar energy available when and where it is required is crucial towards increasing its utilization. Dissociating steam and/or carbon dioxide to chemical fuels is a promising route for storing solar energy. The objective of this work is to design a new class of photo-electrochemical cells that operates at 500 to 700 deg. C rather than at room temperature by utilizing an all solid-state design. Using an oxide heterojunction consisting of a semiconducting light absorber and a mixed oxygen ion and electron conducting oxide, incident solar energy above and below the band gap of the light absorber is converted to thermal energy, which in turn increases the solar-to-fuel efficiency. Unlike conventional photovoltaic-based approaches, here the solar-to-fuel efficiency increases, rather than decreases, with temperature. Thin-film heterojunctions consisting of oxides such as iron, vanadium, and titanium oxides will be evaluated for their potential in elevated temperature photo-electrochemical water and carbon dioxide splitting. The specific objective is to identify a combination of materials that delivers high solar-to-fuel efficiency and reliability over thousands of hours.The central component of this research is understanding and controlling charge generation, separation, and recombination at the heterojunction between a semiconducting oxide and a mixed ionic and electronic conducting oxide, at temperatures significantly above ambient. In photo-electrochemistry involving oxides, ionic defects such as vacancies must play an important role, yet it is not well understood. By combining rapid material screening, opto-electrochemical and in-situ synchrotron X-ray characterizations of oxide heterojunctions, this research aims to understand the interfacial chemistry and electronic properties at the junction of dissimilar solids under extreme conditions.This research seeks to enhance the viability of storing intermittent solar energy in chemical bonds, and increase the global utilization of solar energy. Beyond energy generation and storage, advanced understanding of charge transport at heterojunctions will benefit scientific fields such as catalysis and high temperature electronics, and applications such as solid-oxide fuel cells and sensors in extreme environments. The project work also provides research opportunities for one graduate student over the duration of the project. In addition to incorporating the results into undergraduate and graduate curriculums, the PI will develop a unique "Solar After Dark" outreach program. Human interaction with sunlight is one of the most ubiquitous phenomena in daily life and is an excellent vehicle to raise student interest in science and engineering.