Mechanistic Aspects of the Selectivity of RuO2 and Ru–Mn–O Catalysts in Parallel Chlorine and Oxygen Evolutions Reactions
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Mechanistic differences between oxygen evolution and chlorine evolution on Ru-based oxide electrodes in acidic media were assessed by in situ soft X-ray absorption spectroscopy. O K-edge spectra recorded under cyclic polarization in 0.1 M HClO 4 containing variable concentrations of chlorides in energy dispersion mode were used to follow the potential dependence of the key intermediates in the oxygen evolution process as a function of the electrode potential and chloride concentration. In the absence of chlorides, the oxygen evolution reaction (OER) process is characterized by the formation of surface-confined OOH at potentials preceding the onset of the bulk oxygen evolution. In the presence of chlorides, the spectral behavior reflects a change of the electrode selectivity towards chlorine evolution, which shows a suppression of the absorption of the gaseous oxygen as well as intermediates of the OER process. The observed behavior is compliant with a mechanism assuming chlorine binding via surface-confined oxygen atoms. The Ru–Mn–O phases, which are selective for oxygen evolution even in the presence of chlorides, show a different behavior. The sites involved in the OER retain their selectivity to the OER even in the presence of chlorides. The actual mechanism of the OER changes in the presence of chlorides. While in the absence of chlorides one observes accumulation of surface OOH groups only at potentials positive to the onset of the bulk oxygen evolution, the presence of chlorides enables the formation of surface-confined OOH at potentials negative to the onset of the OER. The onset of the actual oxygen evolution, on the other hand, leads to removal of the surface-confined OOH, suggesting that the OER is controlled by the third electron transfer in the presence of chlorides.
Source: ACS electrochemistry.
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: Development of wavelength-dispersive depth-resolved X-ray absorption spectroscopy and real-time observation of reactions in perpendicular direction of films, G4782150172, Real-time operando observation of surface chemical reactions by development of wavelength-dispersive soft X-ray absorption spectroscopy, Real-time observation of photocatalytic reaction at solid-liquid interface by using wavelength-dispersive soft X-ray absorption spectroscopy, 軟X線吸収分光法による水分解光触媒の固液界面における化学反応のリアルタイム観察
OpenAlex ID: W4411420154