CAREER: Advanced Aerosol Synthesis of Metal Oxides for Photocatalytic Applications

技术总结：最重要的是发现新的合成技术，这些技术可以通过可预测的操作来生产具有明确和可控特征的材料。超声波喷雾热解（USP）是一种基于气溶胶的合成技术，利用超声波进行雾化，虽然被广泛认为是合成成分复杂的无机固体的有效途径，但作为合成结构多样颗粒的途径，人们的认识还不够充分。这个CAREER项目由固态和材料化学（SSMC）项目支持，将强调前体设计和分解行为，以及气溶胶液滴相和表面化学，以实现具有USP的结构多样的颗粒，用于光催化应用，包括用于太阳能制氢的水分解。合成目标包括：1)高度定制的二氧化钛光催化剂，其孔隙度、晶相分布和表面装饰都受到控制；2)可见光驱动的二氧化钛光催化剂，具有高活性位点分散。前者将通过开发一种新发现的盐辅助多孔颗粒的途径来实现，其中低熔点盐混合物作为孔模板，预先形成的二氧化钛胶体作为较大多孔颗粒的构建块。后者将通过靶向价带修饰的过渡金属氧化物来实现。在这种情况下，USP将通过偏离惯例和选择前体来获得结构多样化的颗粒，这些前体通过i)反应（例如，复分解方法）或ii)从单一来源前体分解产生模板和/或结构导向剂。鉴于拟议的研究解决了这样一个及时的问题，即可持续能源的发展，在这方面花费相当大的努力对社区进行教育也是至关重要的。为此，我们提出了一个能源大使计划，在该计划中，本科生在资深实验室成员的指导下，回到他们的高中，通过引人入胜的演示来讨论他们的研究。大量资源正被用于开发替代能源平台，以尽量减少与燃烧化石燃料有关的潜在灾难性影响。考虑到太阳为地球提供120,000万亿瓦（TW）的能量，太阳能转换代表了可持续生产13tw的最可行方法，这符合全球人类的需求。这项拟议中的研究旨在开发新材料，利用太阳能将水分解成氢（H2）和氧（O2），其中H2代表一种清洁燃料，在使用过程中不会排放温室气体或其他污染物。新材料将通过基于气溶胶的合成方法制备，重点是发现新的方法，通过使用化学方法生产结构导向剂来控制所产生颗粒的结构和形状。控制所制备颗粒的形状和结构可能提供了一种方法，其中可以选择性地增强材料的理想特征，从而最大化其光捕获性能和表面反应性。考虑到提议的研究解决了这样一个及时的问题，同样重要的是，努力向社区宣传太阳能科学。因此，能源大使计划被提出，在该计划中，本科生在资深实验室成员的指导下，回到他们的高中，通过引人入胜的演示来讨论他们的研究。

TECHNICAL SUMMARYOf fundamental importance is the discovery of new synthetic techniques that can be predictably manipulated to yield materials with defined and controllable features. While widely recognized as a powerful route to compositionally-complex inorganic solids, ultrasonic spray pyrolysis (USP), which is an aerosol-based synthetic technique that uses ultrasound for nebulization, has been under-realized as a synthetic route to architecturally-diverse particles. This CAREER project, supported by the Solid State and Materials Chemistry (SSMC) program will emphasize precursor design and decomposition behavior, as well as aerosol droplet phase and surface chemistry, to achieve architecturally-diverse particles with USP for photocatalytic applications including water splitting for solar H2 generation. Synthetic targets include i) highly-tailored titania photocatalysts in which porosity, crystal phase distribution, and surface decoration are controlled and ii) visible light driven O2-evolving photocatalysts with high active site dispersion. The former will be achieved by exploiting a newly discovered salt-assisted route to porous particles in which low-melting salt mixtures serve as a pore template and pre-formed titania colloids serve as the building blocks to the larger porous particles. The latter will be achieved by targeting valence band modified transition metal oxides. In this case, architecturally-diverse particles will be achieved with USP by deviating from convention and selecting precursors that yield templates and/or structure-directing agents via i) reaction (e.g., metathesis approaches) or ii) decomposition from single-source precursors. Given that the proposed research addresses such a timely issue, the development of sustainable energy sources, it is also of utmost importance that considerable effort be spent educating the community about it. To this aim, an Energy Ambassadors' Program is proposed in which undergraduates, with guidance from senior laboratory members, return to their high schools to discuss their research through an engaging demonstration.NON-TECHNICAL SUMMARYSubstantial resources are being directed toward the development of alternative energy platforms in attempts to minimize the potentially catastrophic effects associated with the burning of fossil fuels. Given that the sun provides the Earth with 120,000 trillion watts (TW) of energy, solar energy conversion represents the most viable means of sustainably producing 13 TW, which is consistent with global human demand. The proposed research aims to develop new materials for harnessing the energy of the sun to split water into hydrogen (H2) and oxygen (O2), with H2 representing a clean fuel that does not emit greenhouse gases or other pollutants upon use. The new materials will be prepared by an aerosol-based synthetic approach, with an emphasis on discovering new ways in which the architecture and shape of the resulting particles can be controlled by producing structure-directing agents using chemical methods. Controlling the shape and architecture of the prepared particles potentially provides a way in which the desirable features of a material can be enhanced selectively, thus maximizing their light harvesting properties and surface reactivity. Given that the proposed research addresses such a timely issue, it is also important that effort be spent educating the community about solar energy science. Thus, an Energy Ambassadors' Program is proposed in which undergraduates, with guidance from senior laboratory members, return to their high schools to discuss their research through an engaging demonstration.