Gibson Gregory, Wang Ziyun, Hardacre Christopher, Lin Wen-Feng
Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, M13 9PL, UK.
Phys Chem Chem Phys. 2017 Feb 1;19(5):3800-3806. doi: 10.1039/c6cp06906a.
The HO splitting mechanism is a very attractive alternative used in electrochemistry for the formation of O. The most efficient catalysts employed for this reaction at room temperature are SnO-based, in particular the Ni/Sb-SnO catalyst. In order to investigate the HO splitting mechanism density functional theory (DFT) was performed on a Ni/Sb-SnO surface with oxygen vacancies. By calculating different SnO facets, the (110) facet was deemed most stable, and further doped with Sb and Ni. On this surface, the HO splitting mechanism was modelled paying particular attention to the final two steps, the formation of O and O. Previous studies on β-PbO have shown that the final step in the reaction (the formation of O) occurs via an Eley-Rideal style interaction where surface O desorbs before attacking surface O to form O. It is revealed that for Ni/Sb-SnO, although the overall reaction is the same the surface mechanism is different. The formation of O is found to occur through a Langmuir-Hinshelwood mechanism as opposed to the Eley-Rideal mechanism. In addition to this the relevant adsorption energies (E), Gibb's free energy (ΔG) and activation barriers (E) for the final two steps modelled in the gas phase have been shown, providing the basis for a tool to develop new materials with higher current efficiencies.
羟基分裂机制是电化学中用于生成氧的一种极具吸引力的替代方法。室温下用于该反应的最有效催化剂是基于SnO的，特别是Ni/Sb-SnO催化剂。为了研究羟基分裂机制，对具有氧空位的Ni/Sb-SnO表面进行了密度泛函理论（DFT）计算。通过计算不同的SnO晶面，发现(110)晶面最稳定，并进一步用Sb和Ni进行了掺杂。在这个表面上，对羟基分裂机制进行了建模，特别关注了最后两步，即O和O的形成。先前对β-PbO的研究表明，反应的最后一步（O的形成）是通过Eley-Rideal型相互作用发生的，其中表面O在攻击表面O形成O之前先解吸。结果表明，对于Ni/Sb-SnO，虽然总体反应相同，但表面机制不同。发现O的形成是通过Langmuir-Hinshelwood机制而不是Eley-Rideal机制发生的。此外，还给出了在气相中建模的最后两步的相关吸附能（E）、吉布斯自由能（ΔG）和活化能垒（E），为开发具有更高电流效率的新材料提供了工具基础。
