Coupling effect between cobalt oxides and carbon for oxygen reduction reaction

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• The oxygen-reduction reaction (ORR) is crucial for energy conversion technologies like fuel cells.
• Carbon-supported cobalt oxide catalysts are promising for ORR but their reaction mechanisms are complex.
• Understanding ORR pathways is essential for optimizing catalyst performance.

Purpose of the Study:

• To investigate the potential-dependent reaction pathways of the oxygen-reduction reaction.
• To elucidate the role of intermediate disproportionation over carbon-supported cobalt oxide catalysts.
• To differentiate reaction mechanisms under varying electrochemical conditions.

Main Methods:

• Electrochemical analysis of carbon-supported cobalt oxide catalysts.
• Potential-dependent mechanistic studies of the oxygen-reduction reaction.
• Intermediate species analysis during ORR.

Main Results:

• The oxygen-reduction reaction exhibits potential-dependent selectivity over carbon-supported cobalt oxide.
• At low potentials, HO(2)(-) disproportionation to O(2) is favored.
• At high potentials, parallel pathways involving HO(2)(-) disproportionation and direct reduction occur.

Conclusions:

• The apparent 4-electron ORR process masks distinct reaction pathways.
• Catalyst behavior under the oxygen-reduction reaction is highly sensitive to applied potential.
• Optimizing ORR catalysts requires understanding potential-specific mechanistic variations.