Atomistic Explanation of the Dramatically Improved Oxygen Reduction Reaction of Jagged Platinum Nanowires, 50 times better than Pt,Journal of the American Chemical Society

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Atomistic Explanation of the Dramatically Improved Oxygen Reduction Reaction of Jagged Platinum Nanowires, 50 times better than Pt
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-04-22 , DOI: 10.1021/jacs.9b13218
Yalu Chen ₁ , Tao Cheng _{1,

2} , William A Goddard ₁

Affiliation

Pt is the best catalyst for the oxygen reduction reactions (ORR) but it is far too slow. Huang and coworkers showed that dealloying 5 nm Ni7Pt3 Nanowires (NW) led to 2 nm pure Pt Jagged NW (J-PtNW) with ORR 50 times faster than Pt/C. They suggested that the under-coordinated surface Pt atoms, mechanical strain, and high electrochemically active surface area (ECSA) are the main contributors. We report here multiscale atomic simulations that further explain this remarkably accelerated ORR activity from the atomistic perspective. We used the ReaxFF reactive force field to convert the 5 nm Ni7Pt3 NW to the jagged 2 nm NW. We applied Quantum Mechanics to find that 14.4% of the surface sites are barrier-less for , the rate determining step (RDS). The reason is that concave nature of many surface sites pushes the OH bond of the close to the , leading to a dramatically reduced barrier. We used this observation to predict the performance improvement of the J-PtNW relative to Pt (111). Assuming every surface site reacts independently with this predicted rate leads to a 212-fold enhancement at 298.15K, compared to 50 times experimental. The atomic structures of the active sites provide insights for designing high-performance electrocatalysts for ORR.

中文翻译：

锯齿状铂纳米线的氧还原反应显着改善的原子解释，比 Pt 好 50 倍

Pt 是氧还原反应 (ORR) 的最佳催化剂，但它太慢了。Huang 及其同事表明，对 5 nm Ni7Pt3 纳米线 (NW) 进行脱合金可产生 2 nm 纯 Pt 锯齿状 NW (J-PtNW)，其 ORR 比 Pt/C 快 50 倍。他们认为配位不足的表面 Pt 原子、机械应变和高电化学活性表面积 (ECSA) 是主要贡献者。我们在这里报告了多尺度原子模拟，从原子角度进一步解释了这种显着加速的 ORR 活动。我们使用 ReaxFF 反作用力场将 5 nm Ni7Pt3 NW 转换为锯齿状的 2 nm NW。我们应用量子力学发现 14.4% 的表面位点对于速率确定步骤 (RDS) 来说是无障碍的。原因是许多表面位点的凹面性质推动了接近的 OH 键，导致壁垒大大降低。我们使用这一观察结果来预测 J-PtNW 相对于 Pt (111) 的性能改进。假设每个表面位点都与此预测速率独立反应，会导致在 298.15K 处增强 212 倍，而实验为 50 倍。活性位点的原子结构为设计用于 ORR 的高性能电催化剂提供了见解。

更新日期：2020-04-22

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