Composition-adjustable Mo₆Co₆C₂/Co@carbon nanocage for enhanced oxygen reduction and evolution reactions

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Efficient bifunctional electrocatalysts are essential for rechargeable zinc-air batteries.
• Developing catalysts with high activity and stability remains a key challenge.

Purpose of the Study:

• To synthesize and characterize a novel cobalt-molybdenum-based bimetallic carbide and cobalt nanoparticles embedded N-doped carbon nanocage catalyst.
• To investigate the composition-performance relationship of the catalyst for bifunctional oxygen reactions.
• To evaluate the catalyst's performance in rechargeable zinc-air batteries.

Main Methods:

• Synthesis via pyrolysis of a functionalized zeolitic imidazolate framework precursor.
• Coating the precursor with polydopamine and phosphomolybdic acid.
• Characterization of the catalyst's structure and composition.
• Electrochemical testing for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR).
• Assembly and testing of rechargeable zinc-air batteries.

Main Results:

• The catalyst exhibited a low overpotential of 284 mV for OER and a high half-wave potential of 0.865 V for ORR.
• Demonstrated excellent bifunctional durability.
• The catalyst as a cathode improved the zinc-air battery's open-circuit voltage, power density, and specific capacity.
• Achieved remarkable charge-discharge cycle stability in assembled batteries.

Conclusions:

• The synergistic effect of multiple active sites and hollow structure contributes to the catalyst's superior performance.
• This work offers a viable strategy for designing and tuning bifunctional catalysts for energy storage.
• The developed catalyst shows potential for applications in water splitting and other catalytic reactions.