Periodic Reporting for period 2 - SEARCh (SurfacE structure-Activity-Relationship in atomically-defined, ultrathin film perovskite Catalysts)
Berichtszeitraum: 2019-12-01 bis 2020-11-30
Therefore, we investigate Ni-Fe-based perovskite thin film catalysts that can be create with atomic precision to achieve the following objectives:
- Revalidate or replace activity trends found for less well-defined surfaces
- Derive an atomistic understanding of the catalysis reaction and degradation mechanisms
- Deduce design rules for beyond-state-of-the-art electrocatalyst materials and communicate them to the catalyst research and production communities for exploitation in “real-world” catalyst materials
The results of SEARCh will thus contribute to the goals of development and deployment of low-carbon technologies in line with the EU’s Strategic Energy Technology Plan.
2) We showed using operando spectroscopy that the reason for enhanced activity of the transition-metal site is related to a surface phase change: an active, oxyhydroxide type surface layer forms under reaction conditions. This layer can only form for the correct starting termination. So a single atomic layer determines whether an active pahse can form or not.
3) We showed that air exposure leads to alteration of the catalyst surface and a decrease in catalytic activity. Therefore, we developed an air-free transfer system to study the inherent activity of the electrocatalysts (quasi in situ electrochemical testing)
4) We showed that doping with Fe or Co leads to enhancement of the electocatalytic activity of LaNiO3 electrocatalysts.
5) We showed that the epitaxial strain has a comparably small effect on the electrocatalytic activity
6) We showed experimentally and using DFT that for LaNiO3, the (111) crystallographic orientation is the most active. Surprisingly, the (111) orientation is also the most stable surface. Typically, stability and activity show an inverse relationship.
Exploitation and dissemination:
The results listed above have been or will be communicated to the catalysis research com-munity with the goal of exploitation in commercial grade catalysts - based on the insights obtained with our model systems. In addition, each publication is accompanied by press releases and social media posts for communication to the interested public.
Accepted for publication: points 1 and 2 in Nature Materials (accepted for publication. No DOI yet)
To be submitted: point 3
Manuscript in preparation: point 6, more details for point 1 and 2
This realization will lead to general improvement in the optimization of electrocatalysts to make a transition to a hydrogen-based, sustainable industry and society more attainable.
We hope that our results and insights will contribute to a further and faster development of highly efficient electrocatalysts.