Capturing Manganese Oxide Intermediates in Electrochemical Water Oxidation at Neutral pH by In Situ Raman...

Area of Science:

• Electrochemistry
• Catalysis
• Spectroscopy

Background:

• Electrochemical water splitting is crucial for sustainable hydrogen fuel production.
• Manganese-based catalysts are promising for the oxygen evolution reaction (OER).
• The OER mechanism in manganese catalysts lacks direct spectroscopic evidence of active intermediates.

Purpose of the Study:

• To identify water oxidation intermediates on Mn3O4 nanoparticles during OER at neutral pH.
• To provide direct spectroscopic evidence for active Mn-oxo moieties.

Main Methods:

• In-situ Raman spectroscopy was employed to study Mn3O4 nanoparticles.
• Potential-dependent Raman spectroscopy identified characteristic peaks.
• Isotope-labeling and scavenger experiments confirmed intermediate species.

Main Results:

• A potential-dependent Raman peak at 760 cm⁻¹ was observed.
• This peak was assigned to active Mn(IV)=O species.
• Surface terminal Mn(IV)=O intermediates were confirmed.

Conclusions:

• Direct spectroscopic evidence for active Mn(IV)=O species in OER was obtained.
• This study advances the understanding of the OER mechanism on manganese oxides.
• Provides a framework for observing reaction intermediates in catalytic systems.