Esan Dominic A, Trenary Michael
Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor St., Chicago, Illinois 60302, USA.
J Chem Phys. 2021 Mar 21;154(11):114701. doi: 10.1063/5.0042686.
The adsorption of CO on Pt nanoclusters on a single layer of graphene epitaxially grown on the Ru(0001) surface [Gr/Ru(0001)] was studied with reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD). The graphene layer was grown through exposure to ethylene using a method that has previously been shown to completely cover the surface. As CO adsorbs on Ru(0001) but not on graphene, the complete coverage of the Ru(0001) surface by graphene was verified with TPD as no CO adsorption was detectable. Previous work has demonstrated that Pt nanoclusters nucleate in the moiré unit cells of the Gr/Ru(0001) surface. Exposure of the Pt/Gr/Ru(0001) surface to CO gives rise to strong RAIRS peaks at 2065-2085 cm assigned to CO at Pt atop sites and at 1848 cm due to CO at Pt bridge sites. The CO TPD peak areas were used to quantify the CO coverage, which allowed for the determination of the RAIRS peak areas per CO molecule. It was found that the RAIRS intensity for CO on Pt/Gr/Ru(0001) is as much as nine times the intensity of CO on Ru(0001) on a per molecule basis. A more modest intensity enhancement was observed compared to CO on Pt islands on the Ru(0001) surface.
利用反射吸收红外光谱（RAIRS）和程序升温脱附（TPD）研究了一氧化碳在Ru(0001)表面外延生长的单层石墨烯[Gr/Ru(0001)]上的铂纳米团簇上的吸附情况。石墨烯层通过暴露于乙烯中生长，采用的方法先前已证明能完全覆盖表面。由于一氧化碳吸附在Ru(0001)上而不吸附在石墨烯上，通过TPD验证了石墨烯对Ru(0001)表面的完全覆盖，因为未检测到一氧化碳吸附。先前的工作表明，铂纳米团簇在Gr/Ru(0001)表面的莫尔晶胞中形核。将Pt/Gr/Ru(0001)表面暴露于一氧化碳中，在2065 - 2085 cm处出现归因于铂顶位一氧化碳的强RAIRS峰，在1848 cm处出现归因于铂桥位一氧化碳的峰。一氧化碳TPD峰面积用于量化一氧化碳覆盖度，从而确定每个一氧化碳分子的RAIRS峰面积。发现以每个分子计，Pt/Gr/Ru(0001)上一氧化碳的RAIRS强度是Ru(0001)上一氧化碳强度的九倍之多。与Ru(0001)表面铂岛状结构上的一氧化碳相比，观察到强度增强较为适度。
