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@ARTICLE{Scharf:642839,
      author       = {Scharf, Carl Hendric and Chandraraj, Alex and Dyk, Konrad
                      and Stebner, Felix and Lepin, Sören and Tian, Jing and El
                      Bergmi Byaz, Laila and Stettner, Jochim and Leppin,
                      Christian and Kotova, Anastasiia and Reinke, Sebastian and
                      Linnemann, Julia and Maroun, Fouad and Magnussen, Olaf},
      title        = {{R}ole of defects in reversible surface restructuring and
                      activity of {C}o$_3${O}$_4$ oxygen evolution
                      electrocatalysts},
      reportid     = {PUBDB-2025-05645},
      year         = {2025},
      abstract     = {Overcoming the slow kinetics of the oxygen evolution
                      reaction at the anode is a key challenge for the sustainable
                      production of hydrogen via electrolysis. This reaction
                      operates at very positive potentials where the
                      electrocatalyst is exposed to highly oxidative conditions
                      and prone to potential-dependent surface structural
                      transformations. While substantial evidence for such surface
                      restructuring exists, its extent and relevance for the
                      catalysts’ activity is unclear. We address this topic for
                      the case of Co$_3$O$_4$, one of the best known
                      electrocatalysts exhibiting surface transformations, by
                      studies of epitaxial (111)-ordered electrodeposited films
                      with combined operando surface X-ray diffraction,
                      electrochemical impedance spectroscopy, and electrochemical
                      measurements on rotating disk electrodes. Comparison of the
                      as-prepared and the annealed state of the same samples,
                      which both are stable even under long-term oxygen evolution
                      conditions, provides clear insight into the role of surface
                      defects. Our results show that defect-free annealed
                      Co$_3$O$_4$(111) surfaces are structurally stable over a
                      wide potential range and hydroxylate via adsorption at
                      surface oxygen and Co sites. Potential-induced surface
                      restructuring of the Co$_3$O$_4$ lattice only occurs in the
                      presence of surface defects, leading to the formation of the
                      well-known nanometer-thick oxyhydroxide skin layer. The
                      presence of this skin layer promotes oxygen evolution at low
                      overpotentials, but results in higher Tafel slopes. As a
                      result, highly ordered Co$_3$O$_4$(111) surfaces are more
                      active at high current densities than defective Co$_3$O$_4$
                      surfaces that undergo surface transformation. These results
                      highlight that strategies for catalyst surface defect
                      engineering need to be application-oriented.},
      cin          = {DOOR ; HAS-User / UKiel / EPTFR / U Bochum},
      cid          = {I:(DE-H253)HAS-User-20120731 / I:(DE-H253)UKiel-20120814 /
                      I:(DE-H253)EPTFR-20180421 / $I:(DE-H253)U__Bochum-20201205$},
      pnm          = {6G3 - PETRA III (DESY) (POF4-6G3) / FS-Proposal: I-20230748
                      (I-20230748) / DFG project G:(GEPRIS)388390466 - TRR 247:
                      Heterogene Oxidationskatalyse in der Flüssigphase –
                      Materialien und Mechanismen in der thermischen, Elektro- und
                      Photokatalyse (388390466) / FS-Proposal: I-20220824
                      (I-20220824)},
      pid          = {G:(DE-HGF)POF4-6G3 / G:(DE-H253)I-20230748 /
                      G:(GEPRIS)388390466 / G:(DE-H253)I-20220824},
      experiment   = {EXP:(DE-H253)P-P23-20150101},
      typ          = {PUB:(DE-HGF)25},
      doi          = {10.26434/chemrxiv-2025-5901g},
      url          = {https://bib-pubdb1.desy.de/record/642839},
}