Tailored microcells for probing real-time electrocatalytic reactions in TEM
- Abstract number
- 974
- Event
- European Microscopy Congress 2020
- DOI
- 10.22443/rms.emc2020.974
- Corresponding Email
- [email protected]
- Session
- PST.6 - In-situ and in-operando microscopy
- Authors
- Mr. Tzu-Hsien Shen (1), Prof. Yang Shao-Horn (2), Prof. Vasiliki Tileli (1)
- Affiliations
-
1. EPFL
2. MIT
- Keywords
Electrocatalysis, Functional oxides, and Operando liquid-phase TEM
- Abstract text
Understanding the interaction between surface and aqueous solutions is key to enhancing the performance and activity of electrocatalysts for water splitting (H2O → 2H2 + O2). Recently, electrochemical liquid-phase transmission electron microscopy (TEM) has been applied to study reactions in solutions such as metal deposition, fuel cells, and batteries [1–3]. For the operation of electrochemical liquid-phase TEM, electrochemical MEMS chips with ultra-thin membranes and thin-film electrodes are needed. However, to interpret the electrochemical response in such a confined system, tailored micro-cell configurations for targeted electrocatalytic reactions are needed.
Herein, we describe the optimized microfabrication of MEMS-based chips designed for the oxygen evolution reaction. Electrode configurations including material selection, thickness and design were prepared in-house. The imaging was performed in zero-loss energy-filtering mode to enhance the image contrast by removing inelastic scattering and additional aberrations caused by the liquid layer. A direct electron camera with high sensitivity and temporal resolution was used to minimize electron-beam effects and record in real-time the surface catalytic reactions.
The optimized system was tested on three different oxide catalysts, Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), CoO and Co3O4 for the anodic oxygen evolution reaction in 0.1 M KOH. Unlike the other oxides, BSCF exhibited significant shrinkage at the beginning of cyclic voltammetry (CV) measurements that is attributed to Ba/Sr secondary phase dissolution. Interestingly, a change in the wetting behavior and associated surface functionalization of the BSCF particles was demonstrated at 1.1 V vs. RHE during cathodic scans. The wettability of oxides catalysts has been previously related to their electronic structure which is linked to the OER catalytic properties [4,5]. Thus, the ability to perform tailored operando measurements for electrocatalytic applications in a TEM has provided unprecedented insights into surface catalytic reactions of Co-based oxides.
- References
[1] V Beermann et al, Energy & Environmental Science 12 (2019), p. 2476.
[2] E R White et al, ACS Nano 6 (2012), p. 6308.
[3] A J Leenheer et al, ACS Nano 10 (2016), p. 5670.
[4] J Suntivich et al, Science 334 (2011), p. 1383.
[5] K A Stoerzinger et al, Journal of Physical Chemistry C 119 (2015), p. 18504.
[6] The work was supported by the Swiss National Research Foundation (SNF) under award no. 200021_175711.