Wang Shiyi, Zhu Enbo, Huang Yu, Heinz Hendrik
Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, CO 80309, USA.
Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA.
Sci Adv. 2021 Jun 9;7(24). doi: 10.1126/sciadv.abb1435. Print 2021 Jun.
The oxygen reduction reaction (ORR) on platinum catalysts is essential in fuel cells. Quantitative predictions of the relative ORR activity in experiments, in the range of 1 to 50 times, have remained challenging because of incomplete mechanistic understanding and lack of computational tools to account for the associated small differences in activation energies (<2.3 kilocalories per mole). Using highly accurate molecular dynamics (MD) simulation with the Interface force field (0.1 kilocalories per mole), we elucidated the mechanism of adsorption of molecular oxygen on regular and irregular platinum surfaces and nanostructures, followed by local density functional theory (DFT) calculations. The relative ORR activity is determined by oxygen access to platinum surfaces, which greatly depends on specific water adlayers, while electron transfer occurs at a similar slow rate. The MD methods facilitate quantitative predictions of relative ORR activities of any platinum nanostructures, are applicable to other catalysts, and enable effective MD/DFT approaches.
铂催化剂上的氧还原反应（ORR）在燃料电池中至关重要。由于对反应机理的理解不完整且缺乏计算工具来解释活化能方面相关的微小差异（<2.3千卡/摩尔），在实验中对相对ORR活性进行1至50倍范围内的定量预测一直具有挑战性。我们使用具有界面力场（0.1千卡/摩尔）的高精度分子动力学（MD）模拟，阐明了分子氧在规则和不规则铂表面及纳米结构上的吸附机制，随后进行了局域密度泛函理论（DFT）计算。相对ORR活性由氧与铂表面的接触情况决定，这在很大程度上取决于特定的水吸附层，而电子转移以相似的缓慢速率发生。MD方法有助于对任何铂纳米结构的相对ORR活性进行定量预测，适用于其他催化剂，并能实现有效的MD/DFT方法。
