Miranda-Rojas Sebastián, Sierra-Rosales Paulina, Muñoz-Castro Alvaro, Arratia-Pérez Ramiro, Zagal José Heráclito, Mendizábal Fernando
Chemical Processes and Catalysis (CPC), Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Avenida República 275, Santiago, Chile.
Centro de Investigación de los Procesos Redox (CiPRex), Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Sergio Livingstone Polhammer 1007, Independencia, Santiago, Chile.
Phys Chem Chem Phys. 2016 Oct 26;18(42):29516-29525. doi: 10.1039/c6cp06156g.
The need of deeper insights regarding the inner working of catalysts represents a current challenge in the search of new ways to tune their activities towards new chemical transformations. Within this field, metallophthalocyanines-based (MPc) electrocatalysis has gained tremendous attention due to their versatility, low cost, great stability and excellent turn-over properties. In this concern, here we present a quantum chemical study of the formation of supramolecular complexes based on the adsorption of MPcs on gold substrates, and the effect of the substrate on their electrocatalytic properties. For this purpose, we used iron- (FePc), cobalt- (CoPc) and copper-phthalocyanines (CuPc). To model the gold surface we used two gold clusters of different sizes, given by Au and Au accounting for gold electrode Au(111) surface. Thus, both electronic and binding strength features of the adsorption process between the complexes were analyzed in detail in order to gain a deeper description of the nature of the MPc-Au(111) formation, by using Density Functional Theory (DFT) calculations, at the PBE and TPSS levels including the dispersive contribution according to the Grimme approach (D3). Our results show that dispersion forces rule the MPc-gold interaction, with binding strengths ranging between 61 and 153 kcal mol, in agreement to the reported experimental data. To provide a detailed picture of our findings we used the non-covalent interactions index (NCIs) analysis, which offers additional chemical insights regarding the forces that control their interaction strength. Finally, our calculations revealed that among the three MPcs, CuPc required less energy for its oxidation. However, the removal of the electron involves a tremendous decrease of the MPc-gold surface interaction strength thus suggesting its desorption, which would prevent the required reversibility of the redox reaction, explaining its low performance observed experimentally.
深入了解催化剂的内部作用机制是当前寻找新方法来调节其对新化学转化反应活性的一项挑战。在这一领域，基于金属酞菁（MPc）的电催化因其多功能性、低成本、高稳定性和出色的周转性能而备受关注。在此背景下，我们开展了一项量子化学研究，探讨基于MPc在金基底上的吸附形成超分子复合物的过程，以及基底对其电催化性能的影响。为此，我们使用了铁酞菁（FePc）、钴酞菁（CoPc）和铜酞菁（CuPc）。为了模拟金表面，我们使用了两个不同尺寸的金簇，分别为Au和Au，以代表金电极Au(111)表面。通过密度泛函理论（DFT）计算，在PBE和TPSS水平上，包括根据Grimme方法（D3）考虑色散贡献，详细分析了复合物之间吸附过程的电子和结合强度特征，以便更深入地描述MPc-Au(111)形成的本质。我们的结果表明，色散力主导了MPc与金之间的相互作用，结合强度在61至153 kcal/mol之间，与报道的实验数据一致。为了详细说明我们的发现，我们使用了非共价相互作用指数（NCI）分析，该分析提供了关于控制其相互作用强度的力的额外化学见解。最后，我们的计算表明，在三种MPc中，CuPc氧化所需的能量较少。然而，电子的去除会导致MPc与金表面相互作用强度大幅下降，从而表明其解吸，这将阻止氧化还原反应所需的可逆性，解释了其实验观察到的低性能。
