Highly Selective, Active, and Stable Metal Nanoparticle Catalysts with Ultra-Thin Porous Ceramic Shells for Size-Selective Chemical Reactions

具有金属芯和多孔壳结构的尺寸选择性催化剂可以通过对反应物的分子区分来提高反应的选择性。通过调节多孔膜的孔径，可以提高催化剂的选择性。然而，选择性的提高通常是以牺牲催化反应性为代价的。该项目旨在开发制备具有高选择性和高活性的纳米结构尺寸选择性催化剂的方法。所提出的尺寸选择性催化剂制备策略可以应用于多种负载金属催化剂，也可以应用于其他领域，包括传感器、燃料电池、电池和超级电容器。该项目的主要目标是：(a)开发一种新型的纳米结构尺寸选择性催化剂，在每个金属纳米颗粒表面覆盖纳米级（小于5纳米厚）多孔陶瓷覆盖层；(b)对催化剂的结构-活性-选择性关系有一个基本的了解。采用一种独特的分子层沉积（MLD）技术合成具有精确厚度控制和良好多孔结构的高多孔覆盖层。孔隙的大小可以通过改变MLD的化学性质、氧化物类型和多孔结构的形成方法来控制。他们计划将这个项目的成果引入密苏里理工大学的化学工程课程，并开发一门新课程：“催化中的纳米技术”。研究生和本科生将被招募参加这个研究项目，特别强调通过与密苏里州林肯大学（1890年历史上的黑人大学）的合作，招募代表性不足的少数民族。一年一度的“纳米材料展”将被开发并用于激发普通观众和K-12学生对化学工程和纳米技术领域的兴趣。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。

Size-selective catalysts with metal cores and porous shell structures can increase reaction selectivity through molecular discrimination of reactants. The selectivity of a catalyst can be improved by tuning the pore size of the porous films. However, selectivity is generally improved at the expense of catalytic reactivity. The proposed project is aimed at developing methods for preparing nanostructured size-selective catalysts that exhibit both high selectivity and activity. The proposed strategy for size-selective catalyst preparation can be applied to a great variety of supported metal catalysts and may also find applications in other fields, including sensors, fuel cells, batteries, and supercapacitors.The primary objectives of this project are: (a) to develop a novel nanostructured size-selective catalyst with a nanoscale (less than 5 nm thick) porous ceramic overlayer capped on every metal nanoparticle surface and (b) to gain a fundamental understanding of the structure-activity-selectivity relationships of the catalysts. A unique molecular layer deposition (MLD) technique will be utilized to synthesize the highly porous overlayers with precise thickness control and well-defined porous structures. The sizes of pores can be controlled by altering MLD chemistry, oxide types, and formation methods of porous structures. There is a plan to introduce results from this project into the Chemical Engineering curriculum at Missouri S&T and develop a new course: "Nanotechnology in Catalysis". Graduate and undergraduate students will be recruited to participate in this research project with special emphasis on recruiting underrepresented minorities through a collaboration with Lincoln University of Missouri - an 1890 Historically Black College & University. An annual " Nanomaterials Show" will be developed and used to stimulate interest of general audiences and K-12 students in the field chemical engineering and nanotechnology.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.