Title: The role of an interface in stabilizing reaction intermediates for hydrogen evolution in aprotic electrolytes

Abstract

By combining idealized experiments with realistic quantum mechanical simulations of an interface, we investigate electro-reduction reactions of HF, water and methanesulfonic acid (MSA) on the single crystal (111) facets of Au, Pt, Ir and Cu in organic aprotic electrolytes, 1 M LiPF₆ in EC/EMC 3:7W (LP57), the aprotic electrolyte commonly used in Li-ion batteries, 1 M LiClO₄ in EC/EMC 3:7W and 0.2 M TBAPF₆ in 3 : 7 EC/EMC. In our previous work, we have established that LiF formation, accompanied by H₂ evolution, is caused by a reduction of HF impurities and requires the presence of Li at the interface, which catalyzes the HF dissociation. In the present paper, we find that the measured potential of the electrochemical response for these reduction reactions correlates with the work function of the electrode surfaces and that the work function determines the potential for Li⁺ adsorption. The reaction path is investigated further by electrochemical simulations suggesting that the overpotential of the reaction is related to stabilizing the active structure of the interface having adsorbed Li⁺. Li⁺ is needed to facilitate the dissociation of HF which is the source of protons. Further experiments on other proton sources, water and methanesulfonic acid, show that ifmore » the hydrogen evolution involves negatively charged intermediates, F^- or HO^-, a cation at the interface can stabilize them and facilitate the reaction kinetics. When the proton source is already significantly dissociated (in the case of a strong acid), there is no negatively charged intermediate and thus the hydrogen evolution can proceed at much lower overpotentials. This reveals a situation where the overpotential for electrocatalysis is related to stabilizing the active structure of the interface, facilitating the reaction rather than providing the reaction energy.« less

Authors:

Castelli, Ivano E.  ^[1];

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Zorko, Milena ^[2]; Østergaard, Thomas M. ^[1]; Martins, Pedro F. B. D. ^[2]; Lopes, Pietro P.  ^[2];

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Antonopoulos, Byron K. ^[3]; Maglia, Filippo  ^[4];

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Markovic, Nenad M. ^[2]; Strmcnik, Dusan ^[2]; Rossmeisl, Jan  ^[1]

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+ Show Author Affiliations

1. Nano-Science Center; Department of Chemistry; University of Copenhagen; Copenhagen Ø; Denmark
2. Materials Science Division; Argonne National Laboratory; Argonne; USA
3. Battery Cell Technology; BMW Group; München; Germany
4. Battery Cell Technology; BMW Group; München; Germany; Institute for Advanced Study

Publication Date:

2020-01-01

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; BMW Technology Corporation; Technical University of Munich

OSTI Identifier:

1607944

Alternate Identifier(s):

OSTI ID: 1633428

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Published Article

Journal Name:

Chemical Science

Additional Journal Information:

Journal Name: Chemical Science Journal Volume: 11 Journal Issue: 15; Journal ID: ISSN 2041-6520

Publisher:

Royal Society of Chemistry

Country of Publication:

United Kingdom

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY