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arXiv 2201.07605physics.chem-phcond-mat.mtrl-sci
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不同粒径Pt纳米粒子电化学氧化过程的模拟

Simulations of the Electrochemical Oxidation of Pt Nanoparticles of Various Shapes

Björn Kirchhoff, Christoph Jung, Hannes Jónsson, Donato Fantauzzi, Timo Jacob

摘要:

铂纳米颗粒(NP)的活性和稳定性不仅受其大小的影响,还取决于其形状。为此,模拟可以识别结构-性质关系,以在最有希望的结构上做出先验决定。虽然活性通常通过简化表面模型上的电子结构计算来探测,但由于相关过程(例如氧化超过可逆性点)的长时间尺度,对NP模型系统在电化学反应中的稳定性进行建模是具有挑战性的。在这项工作中,例行模拟电催化剂的稳定性。该程序被称为GREG后,其主要成分-一个大正则模拟方法使用反应力场来模拟电化学反应作为原电池电位的函数。GREG例程应用于研究3 nm八面体、立方、十二面体、立方八面体、球形和四面体铂纳米颗粒的氧化。氧化过程进行了分析,使用吸附等压线以及相互作用能热图,为构建电化学相图提供了基础。表面氧化起始电位按立方~=十二面体<=八面体<=四面体<球面<立方八面体的顺序增加,建立了氧化行为与表面小面结构之间的关系。电化学结果合理化,使用结构和电子分析。

英文摘要:

The activity and stability of a platinum nanoparticle (NP) is not only affected by its size but additionally depends on its shape. To this end, simulations can identify structure-property relationships to make a priori decisions on the most promising structures. While activity is routinely probed by electronic structure calculations on simplified surface models, modeling the stability of NP model systems in electrochemical reactions is challenging due to the long timescale of relevant processes such as oxidation beyond the point of reversibility. In this work, a routine for simulating electrocatalyst stability is presented. The procedure is referred to as GREG after its main ingredients - a grand-canonical simulation approach using reactive force fields to model electrochemical reactions as a function of the galvanic cell potential. The GREG routine is applied to study the oxidation of 3 nm octahedral, cubic, dodecahedral, cuboctahedral, spherical, and tetrahexahedral platinum NPs. The oxidation process is analyzed using adsorption isobars as well as interaction energy heat maps that provide the basis for constructing electrochemical phase diagrams. Onset potentials for surface oxidation increase in the sequence cube ~= dodecahedron <= octahedron <= tetrahexahdron < sphere < cuboctahedron, establishing a relationship between oxidation behavior and surface facet structure. The electrochemical results are rationalized using structural and electronic analysis.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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