Poster Presentation Royal Australian Chemical Institute National Congress 2026

Revealing grain dependent glucose oxidation pathways on gold via correlative SECCM and EBSD analysis. (#404)

Anuradha Irugalbandaralage 1 , Anju Singh 1 , Moonika Widjajana 2 , Levi Tegg 3 , Jiancheng Lin 1 , Kourosh Kalantar-Zadeh 2 , Kaye Minkyung Kang 1
  1. School of Chemistry, The University of Sydney, Camperdown, NSW, Australia
  2. School of Chemical and Biomolecular Engineering, The University of Sydney, Darlington , NSW, Australia
  3. School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Camperdown, NSW, Australia

 Understanding grain-dependent glucose oxidation is critical for designing efficient and selective electrocatalysts, as local crystallography strongly influences reaction pathways1,2. We, herein, employ a correlative electrochemical–structural analysis of glucose oxidation on polycrystalline gold, using scanning electrochemical cell microscopy (SECCM) and electron backscatter diffraction (EBSD). Unlike conventional single-crystal studies, which are time-consuming and low throughput, this approach uses SECCM to map activity across many grains in a single experiment, enabling high-throughput correlation of local electrochemical activity with crystallographic structure and overcoming the limitations of conventional polycrystalline measurements. Cyclic voltammetry was conducted point-by-point using a nanopipette probe (~700 nm) to map local current responses across the surface under near-neutral conditions. A total of three SECCM scans were performed, each comprising cyclic voltammetry measurements across 9, 10, and 6 grains, respectively. In all scans, pronounced heterogeneity in the anodic current was observed, reflecting strong grain-dependent electrochemical activity influenced by variations in crystallographic orientation1. As the wetting behavior of the SECCM droplet varied between measurements, with footprint areas typically between 0.6–1.22 µm², and the current scales with the exposed Au area, we developed an image-based normalization approach using post-SECCM SEM analysis. This point-by-point normalization is critical for accurately resolving local electrochemical activity at the low current densities probed (0.1–0.4 mA cm⁻²).  Normalization reveals improved grain-to-grain variations and more accurate spatial differentiation of electrochemical activity than non-normalized electrochemical maps. Correlative SECCM–EBSD analysis shows that crystallographic orientation, Au–OH site availability, and surface regeneration induced by repeated SECCM cycling collectively govern glucose oxidation reaction pathways. These results demonstrate that SECCM enables robust low-current electrochemical measurements while resolving structure–reactivity relationships.

References

1         X. Xu, M. Kang, S. Yan, E. Daviddi, G. West, D. Valavanis, O. J. Wahab and P. R. Unwin, ACS Electrochem., 2025, 9, 1852-1862.

2         R. R. Adzic, M. W. Hsiao and E. B. Yeager, J. Electroanal. Chem.,1989, 260, 475-485.