Elucidating the Role of the Electric Field at the Ni/YSZ Electrode: A DFT Study
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- 作者：Fanglin Che ; Su Ha ; Jean-Sabin McEwen
- 刊名：Journal of Physical Chemistry C
- 出版年：2016
- 出版时间：July 14, 2016
- 年：2016
- 卷：120
- 期：27
- 页码：14608-14620
- 全文大小：761K
- 年卷期：0
- ISSN：1932-7455
文摘
To decrease the deactivation of the Ni/YSZ electrode during hydrocarbon oxidation in solid oxide fuel cells (SOFCs) and coelectrolysis of H2O and CO2 in a solid oxide electrolysis cell (SOEC), it is very important to first understand oxygen vacancy formation at the triple-phase boundary (TPB) of Ni/YSZ because such vacancies are the active sites for coke formation and sulfur poisoning. Furthermore, the effect of the electric fields on oxygen vacancy formation must be investigated because such fields could potentially be used to alter the Ni/YSZ system and directly modify its electrocatalytic performance. In this study, three scenarios were considered: (i) oxygen vacancy formation in YSZ with and without a Ni cluster, (ii) oxygen vacancy formation and oxygen diffusion in YSZ and Ni/YSZ at different oxygen vacancy concentrations, and (iii) the effect of the electric fields on scenarios (i) and (ii). Our computational results show that the oxygen-enriched Ni/YSZ (Ni/YSZ+O) electrode is most likely to occur in an oxygen-enriched environment, even in the presence of different electric fields. Both large negative and positive electric fields could lead to more active TPB vacancies by reducing the vacancy formation energies of the Ni/YSZ+O electrode to a certain degree. Both charge distribution and effective dipole moments verify the qualitative findings concerning field influences on oxygen vacancy formation in Ni/YSZ. Overall, this investigation provides guidance for designing a Ni/YSZ electrode with an improved electrocatalytic performance via the simulated electric fields.