UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Insight into the Nature of Iron Sulfide Surfaces During the Electrochemical Hydrogen Evolution and CO2 Reduction Reactions

Zakaria, SNA; Hollingsworth, N; Islam, HU; Roffey, A; Santos-Carballal, D; Roldan, A; Bras, W; ... de Leeuw, NH; + view all (2018) Insight into the Nature of Iron Sulfide Surfaces During the Electrochemical Hydrogen Evolution and CO2 Reduction Reactions. ACS Applied Materials & Interfaces , 10 (38) pp. 32078-32085. 10.1021/acsami.8b08612. Green open access

[thumbnail of Published article]
Preview
Text (Published article)
Holt_ACSAMI_revised_PUBLISHED.pdf - Published Version

Download (371kB) | Preview
[thumbnail of Supplementary file]
Preview
Text (Supplementary file)
Zakaria_am8b08612_si_001.pdf

Download (1MB) | Preview

Abstract

Greigite and other iron sulfides are potential, cheap, earth-abundant electrocatalysts for the hydrogen evolution reaction (HER), yet little is known about the underlying surface chemistry. Structural and chemical changes to a greigite (Fe3S4)-modified electrode were determined at -0.6 V versus standard hydrogen electrode (SHE) at pH 7, under conditions of the HER. In situ X-ray absorption spectroscopy was employed at the Fe K-edge to show that iron-sulfur linkages were replaced by iron-oxygen units under these conditions. The resulting material was determined as 60% greigite and 40% iron hydroxide (goethite) with a proposed core-shell structure. A large increase in pH at the electrode surface (to pH 12) is caused by the generation of OH- as a product of the HER. Under these conditions, iron sulfide materials are thermodynamically unstable with respect to the hydroxide. In situ infrared spectroscopy of the solution near the electrode interface confirmed changes in the phosphate ion speciation consistent with a change in pH from 7 to 12 when -0.6 V versus SHE is applied. Saturation of the solution with CO2 resulted in the inhibition of the hydroxide formation, potentially due to surface adsorption of HCO3-. This study shows that the true nature of the greigite electrode under conditions of the HER is a core-shell greigite-hydroxide material and emphasizes the importance of in situ investigation of the catalyst under operation to develop true and accurate mechanistic models.

Type: Article
Title: Insight into the Nature of Iron Sulfide Surfaces During the Electrochemical Hydrogen Evolution and CO2 Reduction Reactions
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acsami.8b08612
Publisher version: http://dx.doi.org/10.1021/acsami.8b08612
Language: English
Additional information: This is an open access article published under a Creative Commons Attribution (CC-BY) License (http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html), which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited.
Keywords: greigite, iron sulfide, hydrogen evolution reaction, CO2 reduction, electrocatalyst
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/10057409
Downloads since deposit
201Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item