In this work, we build a microkinetic (MK) model of the CO electro-oxidation reaction using density functional theory (DFT) calculations and scaling relations to understand the interplay between bifunctional mechanisms and electronic modification. A single-site model is first used to identify trends in activity under different operating conditions. The model is then extended to include two site types to understand the surface characteristics necessary for bifunctional activity. For these general cases, we show that the “optimal” adsorption energetics change as a function of the applied potential. We then perform a case study by explicitly modeling both site types in platinum-ruthenium alloy models to assess whether bifunctional or electronic effects are most operative. We find that if these materials indeed remain metallic alloys, then electronic effects are likely dominant, with the sole active sites being electronically-modified Pt sites. Ru sites are spectators that favorably perturb the electronic structure of Pt.

在这项工作中，我们使用密度泛函理论（DFT）计算和比例关系建立了CO电氧化反应的微动力学（MK）模型，以了解双功能机理与电子修饰之间的相互作用。首先使用单站点模型来识别不同操作条件下的活动趋势。然后将模型扩展为包括两个站点类型，以了解双功能活动所需的表面特征。对于这些一般情况，我们表明“最佳”吸附能随所施加电势的变化而变化。然后，我们通过对铂-钌合金模型中的两种位点类型进行显式建模来进行案例研究，以评估双功能或电子效应是否最有效。我们发现如果这些材料确实仍然是金属合金，那么电子效应可能占主导地位，唯一的活性部位是电子修饰的Pt部位。钌位点是有利于扰动铂金电子结构的观众。