Yuk Simuck F, Asthagiri Aravind
William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA.
J Chem Phys. 2015 Mar 28;142(12):124704. doi: 10.1063/1.4915521.
Density functional theory was used to study CO adsorption on thin Pt metal films supported on SrO- and TiO2-terminated SrTiO3(100) surfaces. Regardless of substrate-termination, significant enhancement in CO binding occurred on the Pt monolayer compared to the bulk Pt(100) surface. We also observed CO-coverage dependent shifting of Pt atoms, influenced by the nature of underlying oxide atoms. These oxide-induced effects become negligible after depositing more than 2 monolayers of Pt. Evaluating the electronic structures of oxide-supported Pt showed that the interaction of filled Pt dxz+yz and empty Pt dz(2) states with CO molecular orbitals can be directly related to CO adsorption on the Pt/SrTiO3(100) surface. A hybrid d-band model is able to capture the CO adsorption trends for systems that do not show large lateral distortion except for the case of Pt adsorbed above the Sr atom on the SrO-termination. For this case, charge transfer from adjacent Pt atoms leads to a large filled dz(2) peak below the Fermi level that weakens the Pt-CO σ bonding due to Pauli repulsion.
采用密度泛函理论研究了CO在负载于SrO端和TiO₂端SrTiO₃(100)表面的Pt金属薄膜上的吸附情况。无论衬底终止情况如何，与块状Pt(100)表面相比，Pt单层上的CO结合力都有显著增强。我们还观察到，Pt原子的位置会因CO覆盖度而发生移动，这受到底层氧化物原子性质的影响。在沉积超过2个Pt单层后，这些氧化物诱导效应变得可以忽略不计。对氧化物负载Pt的电子结构进行评估表明，填充的Pt dxz+yz和空的Pt dz(2)态与CO分子轨道的相互作用可直接与CO在Pt/SrTiO₃(100)表面的吸附相关。除了在SrO端位于Sr原子上方吸附的Pt这种情况外，对于不表现出大的横向畸变的体系，混合d带模型能够捕捉CO吸附趋势。对于这种情况，相邻Pt原子的电荷转移导致费米能级以下出现一个大的填充dz(2)峰，由于泡利排斥作用，这削弱了Pt-CO σ键。
