Collaborative Research: Highly Selective Photocatalysis on TiO2 with Atomically Dispersed Active Centers

催化剂加速了化学反应，产生了理想的产物，大大节省了能源和资本成本。光催化剂——那些依赖于太阳能的催化剂——为燃料和化学品的可持续生产提供了一条途径，也促进了环境污染物的修复。该项目将研究新的光催化剂设计，以将天然气升级为高价值产品，并从空气污染物中清除一氧化氮。这项研究将由广泛的教育和推广活动补充，主要针对来自代表性不足背景的K-12和本科生。该项目招募了三名具有催化剂合成、光谱表征技术和计算催化技能的研究人员的专业知识，以制备和表征结构明确、原子分散的多相催化剂上的活性位点。这些催化剂将被评价其控制光驱动反应产物选择性的能力，并阐明相应的反应机理。该项目回应了多相催化中的一个关键挑战，即传统的合成方法通常会导致各种结构不明确的催化位点。这种活性位点的多样性导致反应选择性差，阻碍了对反应机理的阐明。研究人员将通过在二氧化钛（一种原型光催化剂）上合成原子分散的活性中心、单核金属位点和表面氧空位来解决这些挑战。该项目侧重于两个技术上重要的反应，甲烷氧化为甲醇和一氧化氮还原为二氮。这项工作包括使用HAADF-STEM和EXAFS等先进技术对催化剂进行表征。Operando红外，拉曼和x射线光谱将被用来提供对表面反应机制的见解。DFT计算将进一步补充力学信息。该项目有望对控制多相催化反应选择性的因素产生新的见解。该团队将采取多管齐下的方法，让代表性不足的少数民族在各自的机构参与这项研究，并向公众宣传光催化。具体活动包括参加美国国家科学基金会资助的本科生研究经验（REU）计划，这是一门创新课程，面向那些主要宣言不是在科学领域的本科新生，参与与当地高中的外展活动，并与高中教师合作向学生介绍分子建模。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。

Catalysts accelerate chemical reactions toward preferred products with significant savings in energy and capital costs. Photocatalysts - those that rely on the sun's energy - offer a path to sustainable manufacturing of fuels and chemicals, and also facilitate remediation of environmental pollutants. The project will investigate novel photocatalyst designs for upgrading natural gas to higher-value products and clean-up of nitric oxide from air pollutants. The research will be supplemented by a broad range of educational and outreach activities aimed primarily at K-12 and undergraduate students from underrepresented backgrounds.The project enlists the expertise of three investigators with skills in catalyst synthesis, spectroscopic characterization techniques, and computational catalysis to prepare and characterize structurally well-defined and atomically-dispersed active sites on heterogeneous catalysts. The catalysts will be evaluated for their ability to control the product selectivity of photo-driven reactions and to elucidate the corresponding reaction mechanisms. This project responds to a critical challenge in heterogeneous catalysis that traditional synthesis methods often lead to a variety of catalytic sites that are structurally poorly defined. This diversity of active sites leads to poor reaction selectivity and hinders elucidation of reaction mechanisms. The researchers will address these challenges by synthesizing atomically-dispersed active centers, mononuclear metal sites and surface oxygen vacancies, on titanium dioxide, a prototypical photocatalyst. The project focuses on two technologically important reactions, the oxidation of methane to methanol and the reduction of NO to dinitrogen. The effort involves characterization of the catalysts with advanced techniques, such as HAADF-STEM and EXAFS. Operando infrared, Raman, and X-ray spectroscopies will be employed to provide insights into the mechanism of the surface reactions. DFT calculations will further complement the mechanistic information. The project is expected to generate novel insights into the factors that govern the reaction selectivity of heterogeneous catalytic reactions. The team will pursue a multi-pronged approach to engage underrepresented minorities in this research at their respective institutions and to educate the general public about photocatalysis. Specific activities include participation in the NSF-sponsored Research Experience for Undergraduates (REU) Program, an innovative course for freshmen undergraduate students whose primary declarations are not in the sciences, engagement in outreach activities with local high schools, and a collaborative effort with high-school teachers to introduce students to molecular modeling.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.