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。这些纳米粒子强烈吸收阳光。最近的研究表明，当被阳光照射时，它们可以通过一种被称为等离子体催化的过程光解驱动化学转化。在该领域的兴趣是植根于这样一个事实，即与传统的热驱动的化学反应的金属，这些纳米粒子上的光反应提供了更高的效率和产品的选择性的可能性。具体来说，Linic小组正在研究一种假设，即这些纳米粒子的等离子体催化可以通过对其表面组成和结构的特定设计来优化高速率和选择性。该提案有望促进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，以及针对科学领域代表性不足的学生的多项外展工作。根据该奖项，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上的化学反应。这些纳米颗粒的特征在于当用太阳强度的UV-可见光照射时局部表面等离子体共振（LSPR）的共振激发。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，并且与金属上的常规热驱动化学反应相反，在常规热驱动化学反应中，能量不加选择地倾倒到每个可用的反应坐标中（并且控制产物选择性是具有挑战性的），LSPR驱动的反应提供了将能量有效地存款到选择的反应坐标中的机会，导致高效率和产物选择性。该项目的中心假设是，允许更高的反应速率和产物选择性的最佳等离子体材料是具有相对大的等离子体（Ag或Au）纳米颗粒（10 μ m）的等离子体单原子合金（SAA）纳米颗粒，在等离子体纳米颗粒的表面层中增加了其他金属（Pt、Pd、Rh、Ru）的孤立单原子。SAA可能是等离子体纳米颗粒的光捕获潜力和单个原子的化学活性的最佳结合。据推测，这些结构将允许我们在纳米级控制共振能量流，在特定和所需的化学转化中有效地和选择性地控制能量。该提案将通过以下方式检验这一假设：（i）合成等离子体SAA并表征它们的几何形状，（ii）在纳米尺度上研究这些材料中的光能流动，以及（ii）在许多稳态催化过程中测试这些等离子体SAA纳米结构，其中产品选择性至关重要。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的学术价值和更广泛的影响审查标准。

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.