Thermodynamic Full Landscape Searching Scheme for Identifying the Mechanism of Electrochemical Reaction: A Case Study of Oxygen Evolution on Fe- and Co-Doped Graphene-Nitrogen Sites.,The Journal of Physical Chemistry A

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Thermodynamic Full Landscape Searching Scheme for Identifying the Mechanism of Electrochemical Reaction: A Case Study of Oxygen Evolution on Fe- and Co-Doped Graphene-Nitrogen Sites.
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2020-06-10 , DOI: 10.1021/acs.jpca.0c02449
Yanqin Gai _{1,

2} , Gang Tang ₁ , Guoping Gao ₂ , Lin-Wang Wang _{2,

3}

Affiliation

In the literature of heterogeneous water-splitting catalytic thermodynamic study, the computational hydrogen electrode (CHE) scheme is used in the majority of the cases. In this scheme, either the bare surface without O and OH decoration or a decorated phase chosen from a surface Pourbaix diagram is employed as a starting point in a four-electron reaction loop (FERL) to describe the oxygen evolution reaction (OER) process. The electrode potential that makes every step of this FERL exothermic is defined as the thermodynamic overpotential (η_td^OER) of the OER reaction and is often compared with the experimental overpotential. In this study, we point out that for complex systems where each reaction site can bind multiple species, this widely used scheme could lead to wrong η_td^OER. To yield the correct reaction path and η_td^OER, one needs to extend the CHE scheme to a full Gibbs free energy landscape scheme, where all of the intermediate states and their possible transitions are laid out and considered. The correct criterion for η_td^OER should not be “there is no trapped intermediate state (TIS) for any single FERL”, rather “there is no TIS for the whole reaction landscape”. Using transition metal-doped graphene–nitrogen (TMN₄Gra) (TM = Fe and Co) as examples, we show that these two approaches yield different results.

中文翻译：

识别电化学反应机理的热力学全图搜索方案：以Fe和Co掺杂的石墨烯-氮位点上的氧气逸出为例。

在非均相水分解催化热力学研究的文献中，大多数情况下使用计算氢电极（CHE）方案。在此方案中，将没有O和OH装饰的裸露表面或从表面Pourbaix图中选择的装饰相用作四电子反应环（FERL）的起点，以描述氧释放反应（OER）过程。使这个FERL放热的每一步的电极电位被定义为超电势热力学（η _TD^OER）的OER反应的，并且通常与实验超电势相比较。在这项研究中，我们指出，对于每个反应位点都可以结合多个物种的复杂系统，这种广泛使用的方案可能会导致错误的_ηtd^OER。为了产生正确的反应路径和_ηtd^OER，需要将CHE方案扩展到完整的Gibbs自由能态方案，在其中列出并考虑所有中间状态及其可能的跃迁。为η正确的标准_TD^OER不应该是“没有困中间状态（TIS）对于任何单个FERL”，而“没有TIS为整个反应风景”。以过渡金属掺杂的石墨烯-氮（TMN ₄ Gra）（TM = Fe和Co）为例，我们表明这两种方法产生不同的结果。

更新日期：2020-07-02

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