Carbon-Supported Mo₂C for Oxygen Reduction Reaction Electrocatalysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Molybdenum carbide (Mo2C) electrocatalysts are promising for energy applications.
• Carbon supports like carbon nanotubes (CNTs) and carbon xerogel (CXG) influence electrocatalyst performance.
• Understanding capacitive and electrocatalytic properties is crucial for optimizing electrocatalyst design.

Purpose of the Study:

• To synthesize and characterize Mo2C electrocatalysts on CNT and CXG supports.
• To investigate the capacitive properties (double-layer formation) under varying electrolyte cation conditions.
• To evaluate the electrocatalytic activity for the oxygen reduction reaction (ORR) in alkaline media.

Main Methods:

• Preparation of Mo2C electrocatalysts on CNT and CXG supports.
• Electrochemical characterization including cyclic voltammetry to study double-layer capacity.
• Linear scan voltammetry with a rotating disk electrode to assess ORR activity.

Main Results:

• Mo2C/CXG exhibited significantly higher double-layer capacity (75 mF cm-2) than Mo2C/CNT (23 mF cm-2), attributed to CXG's larger surface area.
• Electrolyte cation mobility impacted double-layer formation at higher scan rates.
• Mo2C/CXG demonstrated enhanced ORR performance with higher current densities and more positive potentials compared to Mo2C/CNT.
• The ORR involved an estimated 3-electron transfer, indicating a mixed reaction pathway.

Conclusions:

• Carbon xerogel is a superior support for Mo2C electrocatalysts, enhancing both capacitive and electrocatalytic performance for ORR.
• Electrolyte cation dynamics play a role in the electrochemical behavior of these materials.
• The findings provide insights for designing advanced electrocatalysts for energy conversion devices.