Enhancing CO2 Reduction by Controlling the Ensemble of Active Sites

人工碳回收是一种很有前途的能源和环境可持续性解决方案，利用废弃的二氧化碳作为原料。研究人员的目标是开发一种催化剂，可以更有效地将二氧化碳转化为商业产品的前体或乙醇等液体燃料，从而将燃烧化石燃料产生的二氧化碳作为废物重新利用。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，使用弱结合的第一种金属的核心，在其表面上分散有强结合的第二种金属的原子，将导致结合性能的最佳平衡，并提高催化反应的效率。研究人员将改变催化剂表面强结合金属的数量，然后表征其结构并测试其有效性。这项研究得出的催化剂组成和设计规则有望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培训，并通过与科学与工程女性和家庭学术项目组织合作，促进K-12学生对代表性不足群体的学习。研究人员的目标是通过合成混合金属纳米颗粒催化剂，对实际高表面积催化剂上的二氧化碳还原电催化进行基本的理解，这些催化剂含有弱结合的M1核心（M1 = Au, Ag, Cu）和分散在表面的不同数量的强结合的M2原子（M2 = Ni, Pd, Pt）。他们将测试这样一个假设，即在M1表面上离散的、原子分散的M2集合的催化剂，将表现出M1和M2的优点，并且与单金属催化剂相比，将显示出更高的能源效率和二氧化碳还原的反应速率。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。表面结构和吸收特性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品分解的电催化研究进行探测。这些实验工作将集中使用密度泛函理论和集群扩展计算的结果。本研究中建立的方法和概念有望普遍适用于其他催化材料和反应，为利用这些双金属M2@M1纳米颗粒研究中获得的知识开发非均相催化剂提供新的思路。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。

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.