Speaker
Description
The ever-increasing energy consumption of the world’s population and the looming consequence of climate change require sustainable energy production and storage. One way to store energy is electrochemical water splitting into hydrogen and oxygen [1]. In general, the oxygen evolution reaction (OER) contains the transfer of four electrons and multiple reaction steps on a catalyst before O$_2$ is released. Thereby, transition metals oxides are widely used as electrocatalyst and a common assumption for the OER mechanism is the mono-nuclear mechanism containing the formation of a *-OOH intermediate on a single active transition metal atom. However, also other reaction pathways like the bi-nuclear mechanism with an O-O intermediate or the lattice oxygen mechanism are often conceivable for OER on oxides [2, 3]. Since the activity of a catalyst depends on the rate-determining step, the mechanism is crucial for understanding and developing electrocatalysts.
In acidic conditions, transition metal oxides like Ru and Ir oxides are showing a reasonable catalytic OER activity and stability [4, 5]. But although the so-called Dimensionally Stable Anodes are very successful as OER catalyst, fundamental understandings about the OER mechanism are still missing.
Considering the substantial lack of basic understanding in OER mechanism, it is the aim of this contribution to expand the understanding of the OER mechanism on oxide surfaces. Density functional theory (DFT) computations were used to investigate different OER mechanisms on a rutile IrO$_2$ surface. The study provides important insights into the OER mechanism on transition metal oxides and highlights the urgency of considering different mechanisms for the investigation, understanding and optimization of the electrocatalytic activity.
References:
[1] M. Carmo, D. L. Fritz, J. Mergel, D. Stolten, Int. J. Hydrogen Energy 2013, 38(12), 4901-4934.
[2] M. Busch, Curr. Opin. Electrochem. 2018, 9, 278-284.
[3] E. Fabbri, T. J. Schmidt, ACS Catal. 2018, 8(10), 9765-9774.
[4] S.Trasatti, Electrochim. Acta 2000, 45(15-16), 2377-2385.
[5] M. Escudero-Escribano, A. F. Pedersen, E. A Paoli, R. Frydendal, D. Friebel, P. Malacrida, J. Rossmeisl, I. E. L. Chorkendorff, J. Phys. Chem. B 2018, 122(2), 947-955.