Theoretical Investigation of the Oxygen Reduction Reaction over Platinum Catalysts Supported by Multi‐Edged Vertically Aligned Carbon Nanofiber for Electrocatalyst Preparation
Theoretical Investigation of the Oxygen Reduction Reaction over Platinum Catalysts Supported by Multi‐Edged Vertically Aligned Carbon Nanofiber for Electrocatalyst Preparation
复制标题
多棱垂直排列碳纳米纤维支持的铂催化剂氧还原反应电催化剂制备的理论研究
DOI：
10.1002/celc.202200811
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发表时间：
2022
期刊：
影响因子：
4
通讯作者：
Liu, Bin
中科院分区：
文献类型：
--
作者：
Xu, Jiayi;Elangovan, Ayyappan;Liu, Cong;Li, Jun;Liu, Bin
垂直排列的碳纳米纤维（VACNFs）是燃料电池中氧还原反应（ORR）电催化剂的理想载体。虽然这些催化体系在实验上显示出巨大的潜力，但对催化位点和反应机理缺乏分子认识。本研究采用密度泛函理论（DFT）和经典分子动力学（MD）模拟相结合的多尺度建模方法，研究了铂催化剂在多边VACNF （Pt/VACNF）上的ORR反应性的起源。基于ReaxFF电位，所有纳米级Pt粒子（Pt55， P100和Pt147）都被沿VACNF壁轴向的开放边缘稳定。计算得到的表面铂原子的第一层配位数分别为6.63、7.27和7.85，表明低配位位的比例随着粒径的减小而增加。利用DFT计算系统地探测了OOH、O和OH在pt55上的吸附能。这些吸附能与广义配位数（）保持线性相关。对于VACNF负载的Pt纳米颗粒，我们发现OOH和OH的结合强度分别比Pt（111）强0.14和0.17 eV，这对ORR活性的抑制作用比Pt（111）低。我们的理论预测与线性扫描伏安法很好地吻合，显示了半波电位的左移。
Vertically aligned carbon nanofibers (VACNFs) are promising supports for oxygen reduction reaction (ORR) electrocatalysts in fuel cells. Although experimentally these catalytic systems have shown great potential, there is lack of molecular understanding of the catalytic sites and reaction mechanisms. This work investigated the origin of the ORR reactivities of the platinum catalysts on multi‐edged VACNFs (Pt/VACNF) using a multiscale modeling approach combining Density Functional Theory (DFT) and classical Molecular Dynamics (MD) simulations. Based on the ReaxFF potential, all nanoscale Pt particles (Pt55, P100, and Pt147) are stabilized by the open edges located axially along the VACNF walls. The calculated first‐shell coordination numbers, , of surface Pt atoms are 6.63, 7.27, and 7.85, respectively, suggesting that the percentage of low coordination sites increases as the particle size decreases. The adsorption energies of OOH, O, and OH on Pt55were systematically probed using DFT calculations. These adsorption energies retain a linear correlation against the generalized coordination numbers ( ). For Pt nanoparticles supported on VACNF, we found that the OOH and OH bind stronger than on Pt (111) by 0.14 and 0.17 eV, respectively, which can hinder the ORR activity with lower limiting potential than Pt (111). Our theoretical prediction is in good agreement with the linear sweeping voltammetry that revealed a left shift of the half‐wave potential.