Enhancing CO2 Reduction by Controlling the Ensemble of Active Sites

以废弃的二氧化碳为原料的人工碳回收是一种很有前途的能源和环境可持续发展解决方案。研究人员的目标是开发催化剂，更有效地将二氧化碳纳入商业产品的前体或乙醇等液体燃料中，从而重新利用燃烧化石燃料产生的二氧化碳。有效催化这些反应的主要挑战是平衡反应物的结合和产物的释放。研究人员预测，使用结合较弱的第一金属的核心，在其表面上使用结合较强的第二金属的分散原子，将导致结合性能的最佳平衡，并提高催化反应的效率。研究人员将在催化剂表面添加不同量的强结合金属，然后表征其结构并测试其有效性。这项调查得出的催化剂组成和设计规则预计将鼓励将废二氧化碳纳入燃料和商业产品中。研究人员的教育目标是为研究生和本科生提供动手实验室培训，并通过与女性科学与工程和家庭学术计划组织合作，促进K-12学生的学习，重点放在代表性不足的群体上。研究人员的目标是通过合成含有弱结合M1核(M1=Au，Ag，Cu)的混合金属纳米粒子催化剂，并在表面分散不同数量的强结合M2原子(M2=Ni，Pd，Pt)，以加深对实用高比表面积催化剂上CO2还原电催化的基本理解。他们将检验这样一种假设，即在M1表面具有离散的、原子分散的M2系综的催化剂，将显示出M1和M2的优势，并将显示出与单金属催化剂相比，二氧化碳还原的能效和反应速度更高。这些催化剂的活性将使用间歇电解和气体扩散电极电池进行评估。将使用最先进的电子显微镜和X射线光谱表征、表面特定的电化学分析和产物分解的电催化研究来探索表面结构和吸收特性。这些实验工作将集中在使用密度泛函理论和团簇展开计算的结果。在这项研究中建立的方法和概念预计将普遍适用于其他催化材料和反应，为利用在这些双金属M2@M1纳米粒子研究中获得的知识开发多相催化剂提供新的线索。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Artificial carbon recycling, using waste CO2 as a starting material, is a promising solution for energy and environmental sustainability. The investigators aim to develop catalysts which more efficiently incorporate CO2 into precursors for commercial products or into liquid fuels such as ethanol, thus re-using CO2 generated as waste from burning fossil fuels. The main challenge to efficiently catalyzing these reactions is balancing the binding of the reactants with the release of the products. The investigators predict that using a core of a weakly binding first metal, with dispersed atoms of a strongly binding second metal over its surface, will result in an optimum balance of binding properties and increase the efficiency of the catalyzed reaction. The investigators will vary amount of the strongly binding metal on the catalyst's surface, then characterize its structure and test its effectiveness. The catalyst compositions and design rules resulting from this investigation are expected to encourage incorporating waste CO2 into fuels and commercial products. The investigators' educational goals are to provide hands-on laboratory training to graduate and undergraduate students and to promote learning for K-12 students with a strong focus on underrepresented groups by partnering with the Women in Science and Engineering and Family Academic Program organizations. The investigators aim to develop fundamental understanding of the CO2 reduction electrocatalysis on practical high-surface-area catalysts by synthesizing mixed-metal nanoparticle catalysts containing a weakly binding M1 core (M1 = Au, Ag, Cu) with varying amounts of strongly binding M2 atoms (M2 = Ni, Pd, Pt) dispersed over the surface. They will test the hypothesis that catalysts with discrete, atomically dispersed ensembles of M2 on the surface of M1, will exhibit the advantages of both M1 and M2 and will show to enhanced energy efficiency and reaction rate for CO2 reduction as compared to monometallic catalysts. The activity of these catalysts will be evaluated using batch electrolysis and gas-diffusion electrode cells. The surface structure and absorption properties will be probed using state-of-the-art electron microscopy and X-ray spectroscopic characterizations, surface-specific electrochemical analysis and product-resolved electrocatalytic studies. These experimental efforts will be focused using results from density functional theory and cluster expansion calculations. The methods and concepts established during this study are expected to be generally applicable to other catalytic materials and reactions, shedding new light on the development of heterogeneous catalysts using the knowledge acquired in the investigation of these bimetallic M2@M1 nanoparticles.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.