UNS:Novel Photocatalysts based on TiO2-Passivated III-V Compounds for CO2 Reduction

1512505(克罗宁)这项工作将解决二氧化碳的光催化还原问题，这是一个令人兴奋的反应系统，能够利用阳光将丰富的温室气体转化为可燃碳氢化合物燃料。拟议的研究将通过对光催化反应机理的基本了解来提高二氧化碳光还原的效率。太阳能到电能的直接转换已经达到了非常高的效率和足够低的成本，足以与化石燃料的燃烧竞争。因此，大规模实施千兆瓦太阳能发电厂现在已经成为现实。然而，仍然存在的主要问题是，目前还没有办法储存如此大量的电力，以供在夜间、冬季或阴天使用，而此时阳光并不灿烂。光催化提供了一种将太阳的能量储存在化学键中的方法，这些化学键稍后可以在碳中性循环中释放。具体地说，该提议旨在加深对基于二氧化钛钝化的III-V化合物半导体的新型光催化剂的光催化过程的基本理解。在这里，III-V化合物表面的光腐蚀是由二氧化钛钝化层防止的。为了确定光化学稳定性的程度，这项研究将在几周和几个月内评估这些光催化剂在广泛的二氧化钛厚度和沉积条件下的稳定性。这项研究还将研究在非水(和部分水)离子液体电解液(如[EMIM]BF4)中获得的反应中间体，它抑制了氢的形成，降低了反应中间体的能量，并使更高的过电位得以应用。为了将半导体衬底与金属纳米粒子中的光激发载体的影响分开，还将利用金属纳米粒子在非半导体衬底上进行实验，例如单层石墨。主要研究人员还将继续并扩大在洛杉矶和南加州地区的教育和外展活动，包括为贫困学校的高中教师举办工作坊，增加学生的参与，并开发与光催化相关的实验室套件和演示单元，供教师带回教室。

1512505(Cronin)The work will address photocatalytic reduction of carbon dioxide, which is an exciting reaction system with the ability to convert an abundant greenhouse gas to combustible hydrocarbon fuels using sunlight. The proposed study will enable increased efficiency in carbon dioxide photoreduction through fundamental understanding of the photocatalytic reaction mechanisms. Direct solar-to-electrical energy conversion has reached very high efficiencies and low enough costs to compete with combustion of fossil fuels. As such, large scale implementation of gigawatt solar power plants have now become a reality. The main problem that remains, however, is that currently there is no way of storing this large amount of electricity for use during the night, winter months, or cloudy days, when the sun is not shining. Photocatalysis provides a way to store the sun's energy in chemical bonds that can later be released in a carbon neutral cycle.Specifically, the proposal is aimed at developing a fundamental understanding of photocatalytic processes on novel photocatalysts based on TiO2-passivated III-V compound semiconductors. Here, photocorrosion of the III-V compound surfaces is prevented by the TiO2 passivation layer. In order to establish the extent of photochemical robustness, the study will evaluate the stability of these photocatalysts over weeks and months for a wide range of TiO2 thicknesses and deposition conditions. The study will also investigate the reaction intermediates obtained in non-aqueous (and partially-aqueous) ionic liquid electrolytes (e.g., [EMIM]BF4), which suppress the formation of hydrogen, reduce the energy of the reaction intermediates, and enable the application of higher overpotentials. To separate the effects of the semiconductor substrate from the photoexcited carriers in the metal nanoparticles, experiments will also be carried out utilizing metal nanoparticles on non-semiconducting substrates, such as monolayer graphene.The principal investigators will also continue and expand educational and outreach activities in the Los Angeles and southern California area, including workshops for high school teachers from disadvantaged schools with added participation by their students, and with the development of photocatalysis related lab kits and demo units that will be given to the teachers to take back to their classrooms.