Interfacial Evolution on Co-based Oxygen Evolution Reaction Electrocatalysts Probed by Using In Situ Surface-Enhanced...

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Understanding reactive sites in catalysis is crucial for mechanism elucidation.
• Detecting reaction intermediates in complex systems is challenging.
• Disentangling the roles of different surface atoms in heterogeneous catalysis is difficult.

Purpose of the Study:

• To investigate the synergistic roles of Co²⁺ and Co³⁺ active sites in the electrocatalytic oxygen evolution reaction (OER).
• To elucidate the formation and evolution of reaction intermediates on catalyst surfaces during OER.
• To provide insights into surface component engineering for designing high-performance heterogeneous catalysts.

Main Methods:

• Utilized cobalt oxide (CoO) as a model catalyst.
• Employed in situ surface-enhanced Raman spectroscopy (SERS) to monitor reaction intermediates.
• Conducted ion-substitution experiments and confirmed findings on Co²⁺-Co³⁺ layered double hydroxides (LDHs).

Main Results:

• Identified Co_Oh³⁺ as the catalytic site for OH^- conversion to O-O^- intermediates (1140-1180 cm^-1).
• Determined that CoOOH (503 cm^-1) and CoO₂ (560 cm^-1) active centers at original Co_Td²⁺ sites release O₂.
• Found an optimal Co²⁺/Co³⁺ ratio of 1:1.2 in LDHs for balancing O-O^- generation and O₂ release.

Conclusions:

• Highlighted the synergistic role of cobalt atoms with different valence states in water oxidation.
• Demonstrated the distinct functions of Co_Oh³⁺ and Co_Td²⁺ sites in the OER mechanism.
• Emphasized the importance of surface component engineering for rational catalyst design.