Cation Incorporation into Copper Oxide Lattice at Highly Oxidizing Potentials

Lars Ostervold, Adam Smerigan, Matthew J. Liu, Leah R. Filardi, Fernando D. Vila, Jorge E. Perez-Aguilar, Jiyun Hong, William A. Tarpeh, Adam S. Hoffman, Lauren F. Greenlee, Ezra Lee Clark, Michael J. Janik, Simon R. Bare

Research output: Contribution to journalArticlepeer-review

Abstract

Electrolyte cations can have significant effects on the kinetics and selectivity of electrocatalytic reactions. We show an atypical mechanism through which electrolyte cations can impact electrocatalyst performance─direct incorporation of the cation into the oxide electrocatalyst lattice. We investigate the transformations of copper electrodes in alkaline electrochemistry through operando X-ray absorption spectroscopy in KOH and Ba(OH)2 electrolytes. In KOH electrolytes, both the near-edge structure and extended fine-structure agree with previous studies; however, the X-ray absorption spectra vary greatly in Ba(OH)2 electrolytes. Through a combination of electronic structure modeling, near-edge simulation, and postreaction characterization, we propose that Ba2+ cations are directly incorporated into the lattice and form an ordered BaCuO2 phase at potentials more oxidizing than 200 mV vs the normal hydrogen electrode (NHE). BaCuO2 formation is followed by further oxidation to a bulk Cu3+-like BaxCuyOz phase at 900 mV vs NHE. Additionally, during reduction in Ba(OH)2 electrolyte, we find both Cu-O bonds and Cu-Ba scattering persist at potentials as low as −400 mV vs NHE. To our knowledge, this is the first evidence for direct oxidative incorporation of an electrolyte cation into the bulk lattice to form a mixed oxide electrode. The oxidative incorporation of electrolyte cations to form mixed oxides could open a new route for the in situ formation of active and selective oxidation electrocatalysts.

Original languageEnglish (US)
Pages (from-to)47025-47036
Number of pages12
JournalACS Applied Materials and Interfaces
Volume15
Issue number40
DOIs
StatePublished - Oct 11 2023

All Science Journal Classification (ASJC) codes

  • General Materials Science

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