Towards Electrochemical Hydrogen Storage in Liquid Organic Hydrogen Carriers via Proton-coupled Electron Transfers


Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO2. A possible solution for the transport of H2 in a safe and low-cost way is in the form of liquid organic hydrogen carriers (LOHCs). As an alternative to loading LOHC with H2 via a two-step procedure involving preliminary electrolytic production of H2 and subsequent chemical hydrogenation of the LOHC, we explore here the possibility of electrochemical hydrogen storage (EHS) via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC (R) via a proton-coupled electron transfer (PCET) reaction: . 2 + +2 ― + ox↔ 0 2red We chose 9-fluorenone/fluorenol (Fnone/Fnol) conversion as such a model PCET reaction. The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity, which enabled us to both quantify and get the mechanistic insight on PCET. The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.

Funding source: This work was financially supported by the Swedish Research Council (grant 2016-05990), the Knut and Alice Wallenberg Foundation (H2O2 and Cellfion) and the Swedish Government Strategic Hamid Ghorbani Shiraz, M. Vagin, Tero-Petri Ruoko et al. Journal of Energy Chemistry 73 (2022) 292–300 299 Research Area in Materials Science on Advanced Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No. 2009- 00971).
Countries: Finland ; Sweden

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