Nayakasinghe Mindika Tilan, Guerrero-Sánchez Jonathan, Takeuchi Noboru, Zaera Francisco
Department of Chemistry and UCR Center for Catalysis, University of California, Riverside, California 92521, USA.
Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada, Baja California Código 22800, Mexico.
J Chem Phys. 2021 Mar 14;154(10):104701. doi: 10.1063/5.0040776.
The thermal chemistry of crotonaldehyde on the surface of a polished polycrystalline copper disk was characterized by temperature-programmed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS) and contrasted with previous data obtained on a Pt(111) single crystal substrate. A clear difference in the adsorption mode was identified between the two surfaces, highlighted by the prevalence of RAIRS peaks for the C=C bond on Cu vs for C=O on Pt. Adsorption was also determined to be much weaker on Cu vs Pt, with an adsorption energy on the former ranging from -50 kJ/mol to -65 kJ/mol depending on the surface coverage. The experimental data were complemented by extensive quantum mechanics calculations using density functional theory (DFT) to determine the most stable adsorption configurations on both metals. It was established that crotonaldehyde adsorption on Cu occurs via the oxygen atom in the carbonyl group, in a mono-coordinated fashion, whereas on Pt multi-coordination is preferred, centered around the C=C bond. The contrasting surface adsorption modes seen on these two metals are discussed in terms of the possible relevance to selectivity in single-atom alloy hydrogenation catalysis.
通过程序升温脱附（TPD）和反射吸收红外光谱（RAIRS）对巴豆醛在抛光多晶铜盘表面的热化学性质进行了表征，并与先前在Pt(111)单晶衬底上获得的数据进行了对比。在两个表面之间确定了吸附模式的明显差异，这一点通过RAIRS中Cu表面C=C键峰的普遍存在与Pt表面C=O键峰的普遍存在得以突出体现。还确定了巴豆醛在Cu表面的吸附比在Pt表面弱得多，根据表面覆盖率的不同，前者的吸附能范围为-50 kJ/mol至-65 kJ/mol。通过使用密度泛函理论（DFT）进行的大量量子力学计算对实验数据进行了补充，以确定巴豆醛在两种金属上最稳定的吸附构型。结果表明，巴豆醛在Cu上的吸附是通过羰基中的氧原子以单配位方式进行的，而在Pt上则以围绕C=C键的多配位为主。从与单原子合金加氢催化选择性的可能相关性方面讨论了在这两种金属上观察到的对比鲜明的表面吸附模式。
