CAS: Photocatalysis on Hybrid Plasmonic Materials

在化学系化学催化项目的支持下，密歇根大学的Suljo Linic教授正在研究金属纳米颗粒的光化学转化。这些纳米颗粒强烈吸收阳光。最近的研究表明，当阳光照射时，它们可以通过一种称为等离子体催化的过程光解驱动化学转化。对该领域的兴趣源于这样一个事实，即与传统的金属热驱动化学反应相比，这些纳米颗粒上的光反应提供了更高效率和产物选择性的可能性。具体来说，Linic小组正在研究这样一种假设，即通过对这些纳米颗粒表面组成和结构的特定设计，可以优化其等离子体催化的高速率和选择性。该提案有望提高我们对利用太阳能以环境可持续和节能的方式推动化学的理解。Linic教授和他的学生将参与教育活动，例如开发可持续能源课程，以及针对在科学领域代表性不足的学生的多种推广工作。在这个奖项下，密歇根大学的Suljo Linic教授和他的团队正在研究等离子体金属纳米颗粒的化学反应。这些纳米粒子在太阳强紫外-可见光照射下具有局部表面等离子体共振（LSPR）的共振激发特性。已经证明，在LSPR条件下，这些纳米颗粒可以以有意义的速率激活热电子（空穴）驱动的化学反应，与传统的金属热驱动化学反应相反，能量被不加选择地倾倒到每个可用的反应坐标中（控制产物选择性是具有挑战性的）。lspr驱动的反应提供了有效地将能量沉积到选定的反应坐标的机会，从而提高了效率和产物选择性。该项目的中心假设是，允许更高反应速率和产物选择性的最佳等离子体材料是等离子体单原子合金（SAA）纳米颗粒，具有相对较大的等离子体（Ag或Au）纳米颗粒（10s nm），在等离子体纳米颗粒的表层增加了其他金属（Pt, Pd, Rh, Ru）的孤立单原子。SAAs是等离子体纳米粒子的光捕获潜力和单个原子的化学活性的潜在最佳结合。据推测，这些结构将允许我们在纳米尺度上控制共振能量流，在特定的和期望的化学转化中有效地和有选择地汇集能量。该提案将通过以下方法来验证这一假设：(i)合成等离子体SAA并表征其几何形状，（ii）在纳米尺度上研究这些材料中的光能流动，以及（ii）在一些稳态催化过程中测试这些等离子体SAA纳米结构，其中产物选择性至关重要。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。

With the support of the Chemical Catalysis program in the Division of Chemistry, Professor Suljo Linic of University of Michigan is studying photochemical transformations on metal nanoparticles. These nanoparticles strongly absorb sunlight. It was recently shown that they can photolytically drive chemical transformations when illuminated with sunlight through a process known as plasmonic catalysis. The interest in the field is rooted in the fact that, in contrast to conventional thermally driven chemical reactions on metals, photoreactions on these nanoparticles present the possibility of providing higher efficiencies and product selectivity. Specifically, the Linic group is studying the hypothesis that the plasmonic catalysis of these nanoparticles can be optimized for high rates and selectivities through specific design of their surface composition and structure. The proposal promises to advance our understanding of using solar energy to drive chemistry in an environmentally sustainable and energy efficient manner. Professor Linic and his students will be involved in educational activities, such as development of a sustainable energy course, and multiple outreach efforts directed at underrepresented students in science.Under this award, Professor Suljo Linic and his team at the University of Michigan are studying chemical reactions on plasmonic metal nanoparticles. These nanoparticles are characterized by a resonant excitation of localized surface plasmon resonance (LSPR) when illuminated with solar intensity UV-vis light. It has been demonstrated that under the LSPR conditions, these nanoparticles can activate hot electron (hole)-driven chemical reactions at meaningful rates, and in contrast to conventional thermally driven chemical reactions on metals, where energy is indiscriminately dumped into every available reaction coordinate (and controlling product selectivity is challenging), the LSPR-driven reactions offer the opportunity to efficiently deposit energy into select reaction coordinates leading to high efficiencies and product selectivity. The central hypothesis of the project is that optimal plasmonic materials, allowing for higher reaction rates and product selectivity, are plasmonic single atom alloy (SAA) nanoparticles with a relatively large plasmonic (Ag or Au) nanoparticle (10s of nm), augmented with isolated single atoms of other metals (Pt, Pd, Rh, Ru) in the surface layer of the plasmonic nanoparticle. The SAAs are potentially an optimal marriage of the light harvesting potential of plasmonic nanoparticles and the chemical activity of the single atoms. It is postulated that these structures would allow us to control the resonant energy flow at the nanoscale, funneling energy efficiently and selectively in specific and desired chemical transformations. The proposal will test this hypothesis by: (i) synthesizing plasmonic SAA and characterizing their geometry, (ii) studying the flow of optical energy in these materials at nanoscales and (ii) testing these plasmonic SAA nanostructures in a number of steady state catalytic processes where the product selectivity is of critical importance.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.