Abstract

DFT modeling is used to calculate the free energy profiles of oxygen reduction in acidic and alkaline media on surfaces of nitrogen-doped graphene rather than defect-free graphene. Both four- and two-electron mechanisms of associative reaction are considered. Calculations are made in the grand canonical ensemble at a fixed electrode potential. It is shown that calculations at a fixed potential differ considerably from ones generally accepted at a fixed surface charge. It is found that the electrocatalytic effect of the nitrogen impurity is associated with an increase in the OOH intermediate’s energy of chemisorption that reduces the energy of the oxygen molecule’s protonation reaction. It is also shown that a nitrogen impurity inhibits the two-electron reaction mechanism in an alkaline medium.

中文翻译：

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氮掺杂石墨烯表面氧还原反应的热力学

摘要

DFT 建模用于计算氮掺杂石墨烯（而不是无缺陷石墨烯）表面上酸性和碱性介质中氧还原的自由能分布。考虑了缔合反应的四电子和双电子机制。计算是在固定电极电位的大正则系综中进行的。结果表明，固定电势下的计算与固定表面电荷下通常接受的计算有很大不同。研究发现，氮杂质的电催化效应与OOH中间体化学吸附能量的增加有关，从而降低了氧分子质子化反应的能量。还表明氮杂质抑制碱性介质中的双电子反应机制。