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利用基于平面波的密度泛函理论(DFT)计算研究了氧气分子在Pt(111)表面的吸附和解离,以及解离产物进一步质子化形成H2O的过程.通过使用不同尺寸的平板模型和在表面预吸附不同数量的氧原子,研究了氧覆盖度对氧还原反应(ORR)路径的影响,并对使用不同水合质子模型的计算结果进行了比较.研究结果表明:质子化的end-on化学吸附态OOH*的形成是ORR的初始步骤;OOH*能够转化形成非质子化的top-bridge-top化学吸附态O2*,或者解离形成吸附的O*物种.对不同氧覆盖度下各种可能步骤的活化能计算结果表明,O*的质子化形成OH*物种是ORR的速决步骤.增加氧覆盖度时,该步骤的活化能减少.此外,还发现使用比H7O3+更复杂的水合质子模型不会改变计算所得的反应路径.
The adsorption and dissociation of oxygen molecules on the Pt (111) surface and the further protonation of dissociation products to form H2O were studied by using plane wave-based density functional theory (DFT) calculations. By using plate models of different sizes and surface pre- The effects of oxygen coverage on the oxygen reduction reaction (ORR) pathways were investigated by comparing the results with different hydration proton models. The results show that the protonated end-on chemisorption states The formation of OOH * is the initial step of ORR; OOH * can be converted to form aprotonated top-bridge-top chemisorption state O2 * or dissociated to form adsorbed O * species. For various possible steps under different oxygen coverage The results of activation energy calculation show that the protonation of O * forms the immediate step of ORR in OH * species, and the activation energy of this step increases with the increase of oxygen coverage.In addition, it is also found that hydration proton model more complex than H7O3 + Change the calculated reaction path.