Title:	Computational electrochemistry of conducting polymers
DNr:	SNIC 2019/3-640
Project Type:	SNIC Medium Compute
Principal Investigator:	Viktor Gueskine <viktor.gueskine@liu.se>
Affiliation:	Linköpings universitet
Duration:	2019-11-27 – 2020-12-01
Classification:	10403 10407 10406
Homepage:	http://liu.se/loe
Keywords:

Abstract

The power storage devices such as fuel cells and batteries are needed in development of electronic devices and power generation technologies to realize the global aim towards sustainable power. The cathode of the oxygen-associated fuel cells and air-metal batteries runs the oxygen reduction reaction (ORR) that transforms molecular oxygen into water in a four-electron overall process. On the other hand, the renewal of interest to ORR is due to the research for new ways of hydrogen peroxide production in the framework of the green chemistry. In this case, molecular oxygen undergoes two-electron reduction. However, ORR is usually characterized with high overpotentials and is thus notoriously sluggish, calling for the use of electrocatalysts. Today, expensive noble metal catalysts are commonly utilized to boost the ORR and the resulting conversion efficiency in those devices. Hence, there is an intensive research to find efficient electrodes, exhibiting a favorable electronic structure, for ORR based on non-critical raw materials/elements that can be manufactured using low cost processes, such as conducting polymers. Poly(3,4-ethylenedioxythiophene) [PEDOT] has emerged as novel and reliable material for recycling power and energy storage devices due to its stability, well-established manufacturing technology and excellent optical and electronic properties. During recent years, researchers at te Laboratory of Organic Electronics (LOE) and LiU has significantly advanced the state-of-the-art of this important field. In particular, it was experimentally demonstrated that PEDOT is an efficient and selective heterogeneous catalyst for the direct reduction of oxygen to hydrogen peroxide, as well as can serve as an efficient electrocatalyst for hydrogen production. [1,2] However, to-date reports do not lead to a consensus on the ORR mechanism or resolution of the relative contributions of two- and four-electron ORR pathways; hence, the mechanism of action of the conducting polymer in ORR remains unclear. Earlier theoretical treatments from our laboratory did not sufficiently take into account the complexity of the system.[3] Therefore, there is a strong need to revisit this issue by explicitly posing first some basic questions, formulating general principles based on the answers, and then performing relevant calculations according to the latter. This represents the main aim of the present project where we will perform first-principle DFT calculations to understand thermodynamics, kinetics, and mechanism of reduction of oxygen on PEDOT. One of the features of our study is that the reaction mechanisms of ORR on a conducting polymer, we can be inspired by the wisdom accumulated in understanding molecular and biological catalysis, rather than trying to transpose the mechanisms established for metal electrodes. [1] E. Mitraka et al., Adv. Sustainable Syst. 2019, 3, 1800110 [2] R. Valiollahi et al., Sustainable Energy & Fuels 2019. [3] S. K. Singh, J. Chem. Phys. C 121 (22), 12270.