Deraet Xavier, Turek Jan, Alonso Mercedes, Tielens Frederik, Cottenier Stefaan, Ayers Paul W, Weckhuysen Bert M, De Proft Frank
Department of General Chemistry (ALGC), Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050, Elsene, Brussels, Belgium.
Department of Electrical Energy, Metals, Mechanical Constructions and Systems, Ghent University, Technologiepark 46, 9052, Zwijnaarde, Belgium.
Chemistry. 2021 Apr 1;27(19):6050-6063. doi: 10.1002/chem.202004660. Epub 2021 Mar 4.
The drive to develop maximal atom-efficient catalysts coupled to the continuous striving for more sustainable reactions has led to an ever-increasing interest in single-atom catalysis. Based on a periodic conceptual density functional theory (cDFT) approach, fundamental insights into the reactivity and adsorption of single late transition metal atoms supported on a fully hydroxylated amorphous silica surface have been acquired. In particular, this investigation revealed that the influence of van der Waals dispersion forces is especially significant for a silver (98 %) or gold (78 %) atom, whereas the oxophilicity of the Group 8-10 transition metals plays a major role in the interaction strength of these atoms on the irreducible SiO support. The adsorption energies for the less-electronegative row 4 elements (Fe, Co, Ni) ranged from -1.40 to -1.92 eV, whereas for the heavier row 5 and 6 metals, with the exception of Pd, these values are between -2.20 and -2.92 eV. The deviating behavior of Pd can be attributed to a fully filled d-shell and, hence, the absence of the hybridization effects. Through a systematic analysis of cDFT descriptors determined by using three different theoretical schemes, the Fermi weighted density of states approach was identified as the most suitable for describing the reactivity of the studied systems. The main advantage of this scheme is the fact that it is not influenced by fictitious Coulomb interactions between successive, charged reciprocal cells. Moreover, the contribution of the energy levels to the reactivity is simultaneously scaled based on their position relative to the Fermi level. Finally, the obtained Fermi weighted density of states reactivity trends show a good agreement with the chemical characteristics of the investigated metal atoms as well as the experimental data.
开发具有最大原子效率的催化剂的驱动力，再加上对更可持续反应的不断追求，使得人们对单原子催化的兴趣与日俱增。基于周期性概念密度泛函理论（cDFT）方法，我们获得了关于负载在完全羟基化的无定形二氧化硅表面上的单个晚期过渡金属原子的反应性和吸附的基本见解。特别是，这项研究表明，范德华色散力的影响对于银（98%）或金（78%）原子尤为显著，而第8-10族过渡金属的亲氧性在这些原子与不可约SiO载体的相互作用强度中起主要作用。电负性较小的第4周期元素（Fe、Co、Ni）的吸附能范围为-1.40至-1.92 eV，而对于较重的第5和第6周期金属，除了Pd之外，这些值在-2.20至-2.92 eV之间。Pd的偏离行为可归因于其d壳层完全填充，因此不存在杂化效应。通过对使用三种不同理论方案确定的cDFT描述符进行系统分析，费米加权态密度方法被确定为最适合描述所研究体系反应性的方法。该方案的主要优点是它不受连续带电倒易晶胞之间虚拟库仑相互作用的影响。此外，能级对反应性的贡献会根据它们相对于费米能级的位置同时进行缩放。最后，获得的费米加权态密度反应性趋势与所研究金属原子的化学特性以及实验数据显示出良好的一致性。
