Dynamic Heterovalent Dual-Cu Sites for O═O Cleavage in Electrocatalytic Oxygen Reduction Reaction

Area of Science:

• Energy electrochemistry
• Catalysis science
• Materials science

Background:

• The activation and cleavage of the oxygen-oxygen (O═O) double bond is a critical hurdle in energy electrochemistry.
• Developing efficient catalysts is essential for advancing electrochemical energy conversion technologies.

Purpose of the Study:

• To design and investigate a novel copper dual-atom catalyst (Cu-DAC) for enhanced oxygen reduction reaction (ORR) performance.
• To elucidate the atomic-level mechanisms governing O═O bond cleavage in Cu-DAC.

Main Methods:

• Bottom-up pre-coordination assembly and post-encapsulation pyrolysis for Cu-DAC synthesis.
• Operando spectroscopic characterizations to probe catalyst behavior under reaction conditions.
• Ab initio dynamic simulations (AIMD) to understand reaction mechanisms at the atomic level.

Main Results:

• The synthesized Cu-DAC exhibits a well-defined Cu-Cu distance and switchable Cu¹⁺/Cu²⁺ states.
• Cu-DAC achieves a high half-wave potential (0.87 V_RHE) for ORR with near-unity 4e^- selectivity and excellent stability.
• Operando studies and AIMD revealed a dynamic heterovalent [Cu^1+─O─O^{· -}─Cu²⁺] intermediate that facilitates O-O bond cleavage.

Conclusions:

• The Cu-DAC's dynamic dual-site coordination and heterovalent states are key to its high ORR activity and stability.
• Understanding the dynamic evolution of dual-atom sites provides atomic-level principles for designing next-generation electrocatalysts.
• This work offers a pathway for rationally designing dynamically active catalysts for challenging electrochemical transformations.