Use of lead underpotential deposition for the characterization of electrochemically nanostructured copper surfaces
Pedro Mazaira Couce a, Paula Sebastián Pascual a, Ward van der Stam b, María Escudero Escribano a c
a Department of Chemistry, Center for High Entropy Alloy Catalysis, University of Copenhagen, Universitetsparken, 5, København, Denmark
b Utrecht University, Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Netherlands
c ICREA and Catalan Institute of Nanoscience and Nanotechnology (ICN2), Campus de la, Universitat Autònoma de Barcelona, Edifici ICN2, Av. de Serragalliners, s/n, 08193 Bellaterra, Barcelona, Spain
nanoGe Fall Meeting
Proceedings of Materials for Sustainable Development Conference (MAT-SUS) (NFM22)
#Suschem- Materials and electrochemistry for sustainable fuels and chemicals
Barcelona, Spain, 2022 October 24th - 28th
Organizers: Marta Costa Figueiredo and Raffaella Buonsanti
Poster, Pedro Mazaira Couce, 327
Publication date: 11th July 2022

Copper (Cu) is a unique catalyst capable to convert CO2 into a variety of carbon products like methane (CH4), ethylene (C2H4), or ethanol (C2H5OH). However, the product selectivity toward different carbon products is very spread.[1] Tuning the catalyst surface properties, such as the electroactive surface area and crystalline facets´ distribution, is fundamental for improving the selectivity of the catalyst.[2] In addition, an accurate characterization of the surface structure is essential for the rational design of a more selective catalyst.

In this work, we have used lead under potential deposition (lead UPD) to characterize different Cu surfaces. UPD is an electrochemical technique in which the deposition of a foreign metal (lead) monolayer over the metal electrode is recorded at potentials more favourable than the bulk thermodynamic deposition. The UPD allows the characterization of the catalyst exposed facets due to the difference in potential in which lead gets deposited over each facet.[3]  Using this technique we have recorded a lead UPD profile of  Cu (poly) and of electrochemically nanostructured Cu surfaces using Chloride.[4]  (Figure 1a). Then, using the lead UPD profiles of Cu (111) and (100) single crystals (figure 1b) we have analysed the facet distribution of the different nanostructured copper surfaces, and we have estimated the total surface area and the contribution of each exposed facet. In summary, we have proved that lead UPD is a sensitive and useable technique to characterize the entire Cu surface structure, relevant to understanding the Cu's surface impact on the electrocatalytic reduction of CO2.

Figure 1: a) Lead UPD profile of  a copper surface treated with chloride (green filled area) and a flat polycrystalline copper surface (black dashed line). b) Lead UPD profile of the Cu (100) and (111) single crystals and lead UPD profile of the Cu (poly). Both figures were performed at 5 mV/s with a pH of 3.

The authors acknowledge the support from the Danish National Research Foundation Center for High Entropy Alloys Catalysis (CHEAC, DNRF-149). This work was also supported by the Danish Foundation through DFF-Research Project1 (Thematic Research, green transition) under grant number 0217-00213A. MEE gratefully acknowledges Villum Foundation for financial support through a Villum Youn Investigator Grant (project number:19142)

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