Delarmelina Maicon, Catlow C Richard A
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
UK Catalysis Hub, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK.
R Soc Open Sci. 2022 Feb 23;9(2):211423. doi: 10.1098/rsos.211423. eCollection 2022 Feb.
The role of Y-, Ca- and Ce-doping of cubic zirconia (c-ZrO) (111) surface on its acidity, basicity and the interplay between surface acid-base pairs is investigated by computational methods. The most stable surface structures for this investigation were initially determined based on previous studies of Y-doped c-ZrO (111) and by a detailed exploration of the most stable configuration for Ca-doped c-ZrO (111) and Ce-doped c-ZrO (111). Next, surface mapping by basic probe molecules (NH and pyridine) revealed a general reduction of the acidity of the surface sites, although a few exceptions were observed for zirconium ions at next nearest neighbour (NNN) positions to the oxygen vacancy and at the nearest neighbour (NN) position to the dopants. Adsorption of CO over basic sites revealed a cooperative interplay between acid-base groups. In this case, the overall effect observed was the decrease of the calculated adsorption energies when compared with the pristine surface. Moreover, spontaneous formation of -CO systems from initial -CO configurations indicates a decrease in the required energy for forming oxygen vacancies in the doped ZrO systems at NNN positions or further away from the existing vacancy site.
通过计算方法研究了立方氧化锆（c-ZrO）（111）表面的Y、Ca和Ce掺杂对其酸度、碱度以及表面酸碱对之间相互作用的影响。本研究中最稳定的表面结构最初是基于之前对Y掺杂c-ZrO（111）的研究，并通过详细探索Ca掺杂c-ZrO（111）和Ce掺杂c-ZrO（111）的最稳定构型来确定的。接下来，用碱性探针分子（NH和吡啶）进行表面映射，结果表明表面位点的酸度普遍降低，不过对于与氧空位处于次近邻（NNN）位置以及与掺杂剂处于近邻（NN）位置的锆离子，观察到了一些例外情况。CO在碱性位点上的吸附揭示了酸碱基团之间的协同相互作用。在这种情况下，与原始表面相比，观察到的总体效果是计算得到的吸附能降低。此外，从初始的-CO构型自发形成-CO体系表明，在掺杂的ZrO体系中，在NNN位置或远离现有空位位点形成氧空位所需的能量降低。
