Synthesis of New Intergrowth and Nanostructured Metal Oxyhalide Photocatalysts

我们迫切需要能够吸收可见光的材料，这样这些能量就可以用来驱动它们表面的反应，比如太阳能水分解，它有望提供氢作为一种清洁燃料。金属氧化卤化物是一类令人兴奋的光催化材料，但它们在使用时往往会转化为相应的金属氧化物，使其长期无效。最近，一种含铋金属氧化卤化物在用作光催化剂的过程中被确定为既吸收可见光又耐用。这个项目得到了材料研究部固态和材料化学项目的支持，印第安纳大学的Sara Skrabalak教授和她的研究小组将开发新的材料，将不同的含铋金属氧化化物结合在一起，用于太阳能水分解。这些新材料的原子水平结构也被详细表征，以了解它们的结构如何提供可见光吸收和临界耐久性。这些材料也被合成为具有确定形状的晶体，以便表现出最佳的晶面，以促进水分解反应。这项工作提供了对材料特性的基本见解，具有解决与利用太阳能相关的材料耐久性挑战的潜力。这项研究与广泛的教育和推广活动相结合，以促进公众对材料科学和太阳能的理解。该项目由材料研究部固态与材料化学项目支持，将开发新型金属氧化卤化物互生物Bi4MO8X-Bi2LnO4X的合成方法。这项工作的基本假设涉及到与母体化合物相比，相互生长的形成和化学计量的调制使得它们的电子结构和内部电场的工程能够提高光催化效率和光稳定性。该合成工作与高分辨率电子显微镜和x射线全散射实验的详细结构表征相结合，从而建立了强大的结构-性能相关性。最后的目的是合成形状可控的Bi4MO8X纳米晶体，并研究其表面对光催化性能的影响。总的来说，本研究通过阐明局部和纳米级结构对这些有前途的异阴离子材料的光电性能和光催化性能的作用，推进了耐用金属氧化卤化物的合成和设计。该项目还将支持教育和推广活动，通过与Wonderlab（位于印第安纳州布卢明顿的儿童科学博物馆）和印第安纳大学的ScienceFest合作，向非科学家介绍能源概念。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical summaryThere is a critical need for materials that absorb visible light so that such energy can be used to drive reactions at their surfaces, such a solar water splitting which promises to provide hydrogen as a clean fuel. Metal oxyhalides are an exciting class of such photocatalytic materials but often they will be converted to their corresponding metal oxide upon use, making them ineffective long-term. Recently, a subset of bismuth-containing metal oxyhalides was identified to be both visible light absorbing as well as durable during their use as photocatalysts. With this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, Professor Sara Skrabalak and her research group at Indiana University will develop new materials that combine different bismuth-containing metal oxyhalides for uses in solar water splitting. The atomic level structure of these new materials are also characterized in detail to understand how their structure provides both visible light absorption and critical durability. These materials are also being synthesized as crystals with defined shapes so that the best crystal faces are expressed to facilitate the water splitting reaction. This work provides fundamental insight into the properties of materials, with potential to address material durability challenges associated with harnessing solar energy. The research is paired with broad educational and outreach activities that foster understanding about material science and solar energy to the general public.Technical summaryThis project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, will develop synthetic methods for the growth of new metal oxyhalide intergrowths of the form Bi4MO8X-Bi2LnO4X. The fundamental hypothesis of this work involves the idea that intergrowth formation and modulation of their stoichiometry enables engineering of their electronic structure and internal electric fields toward enhanced photocatalytic efficiency and photostability compared to the parent compounds. This synthetic work is coupled with detailed structural characterization by high resolution electron microscopy and X-ray total scattering experiments so that robust structure-property correlations are established. A final aim focuses on the synthesis of shape-controlled Bi4MO8X nanocrystals and the study of their faceting on photocatalytic performance. Collectively, this research advances the synthesis and design of durable metal oxyhalides by elucidating the roles of local and nanoscale structure on the optoelectronic properties and photocatalytic performance of these promising heteroanionic materials. The project will also support educational and outreach activities that introduce energy concepts to non-scientists through partnerships with Wonderlab (a children’s science museum in Bloomington, Indiana) and Indiana University’s ScienceFest.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.