Yule, Lewis C., Shkirskiy, Viacheslav, Aarons, Jolyon, West, Geoffrey D., Bentley, Cameron Luke, Shollock, Barbara A. and Unwin, Patrick R. (2019) Nanoscale active sites for the hydrogen evolution reaction on low carbon steel. The Journal of Physical Chemistry C . doi:10.1021/acs.jpcc.9b07216 (In Press)

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Abstract

To fully elucidate the structural controls on corrosion-related processes at metal surfaces, experimental measurements should correlate and compare directly structure and activity at the scale of surface heterogeneities (e.g., individual grains, grain boundaries, inclusions etc.). For example, the hydrogen evolution reaction (HER), which usually serves as the cathodic counterpart to anodic metal dissolution in acidic media, may be highly sensitive to surface microstructure, highlighting the need for nanoscale-resolution electrochemical techniques. In this study, we employ scanning electrochemical cell microscopy (SECCM) in conjunction with co-located scanning electron microscopy, electron backscatter diffraction, and energy dispersive X-ray spectroscopy to elucidate the relationship between surface structure/composition and HER activity on low carbon steel in aqueous sulfuric acid (pH ≈ 2.3). Through this correlative electrochemical multimicroscopy approach, we show that the HER activity of the low index grains (slightly) decreases in the order (100) > (111) > (101), with grain-dependent free energy of hydrogen adsorption (calculated for the low index planes of iron using density functional theory, DFT) proposed as a tentative explanation for this subtle structural-dependence. More significantly, we show that the HER is greatly facilitated by sub-micron surface defects, specifically grain boundaries and MnS inclusions, directly identifying these heterogeneities as potential “cathodic sites” during (atmospheric) corrosion. This study demonstrates the considerable attributes of correlative SECCM for identifying nanoscale active sites on surfaces, greatly aiding understanding of corrosion and electrocatalytic processes.

Item Type:	Journal Article
Divisions:	Faculty of Science > Chemistry Faculty of Science > Physics Faculty of Science > WMG (Formerly the Warwick Manufacturing Group)
Journal or Publication Title:	The Journal of Physical Chemistry C
Publisher:	American Chemical Society
ISSN:	1932-7447
Official Date:	9 September 2019
Dates:	Date Event 9 September 2019 Available 9 September 2019 Accepted
Date of first compliant deposit:	12 September 2019
DOI:	10.1021/acs.jpcc.9b07216
Status:	Peer Reviewed
Publication Status:	In Press
Access rights to Published version:	Restricted or Subscription Access
Copyright Holders:	https://doi.org/10.1021/acs.jpcc.9b07216
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID UNSPECIFIED iCASE UNSPECIFIED UNSPECIFIED [EPSRC] Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/501100000266 UNSPECIFIED Tata Steel Research and Development UNSPECIFIED 792948 (NELMA) European Union Horizon 2020 UNSPECIFIED UNSPECIFIED Ramsay Memorial Fellowship Trust UNSPECIFIED UNSPECIFIED Ramsay Memorial Fellowship Trust UNSPECIFIED EP/R018820/1 [EPSRC] Engineering and Physical Sciences Research Council http://dx.doi.org/10.13039/501100000266

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