Controlled O₂ reduction at a mixed-valent (II,I) Cu₂S core

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Oxygen reduction reactions (ORRs) are crucial in energy conversion technologies.
• Controlling the selectivity of ORR towards H2O2 or H2O is a significant challenge.
• Developing efficient and robust catalysts for selective ORR is of high interest.

Purpose of the Study:

• To investigate the catalytic activity of a mixed-valent Cu2S complex for oxygen reduction reactions.
• To explore the tuneability of H2O2 versus H2O production.
• To identify the active catalytic species and understand the reaction kinetics.

Main Methods:

• Utilized a mixed-valent Cu2S complex as a pre-catalyst.
• Performed oxygen reduction reactions under mild conditions.
• Varied the amount of sacrificial reducer to control product selectivity.
• Characterized the catalytic system's activity and stability over multiple cycles.

Main Results:

• Achieved tuneable production of H2O2 versus H2O by controlling the sacrificial reducer concentration.
• Identified the fully reduced bisCu(I) state as the primary active species in solution.
• Observed fast reaction kinetics for the active species.
• Demonstrated the robustness of the catalytic system for H2O2 production over several cycles.

Conclusions:

• The mixed-valent Cu2S complex serves as an effective pre-catalyst for selective oxygen reduction reactions.
• The catalytic system offers a controllable pathway for H2O2 production under mild conditions.
• The identified active species and fast kinetics present opportunities for integration into electrochemical devices.