Constructing highly efficient bifunctional catalysts for oxygen reduction and oxygen evolution by modifying MXene...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for energy conversion technologies.
• MXene materials offer a promising platform for designing novel electrocatalysts due to their unique 2D structure and tunable properties.

Purpose of the Study:

• To propose an efficient pathway for designing MXene-based ORR/OER catalysts.
• To investigate the catalytic performance of transition metal-doped MXene materials at specific defect sites.

Main Methods:

• Computational screening of transition metal (Fe, Co, Ni) doping at vacancy (V_O), H₁, and H₂ sites on M₂CO₂ (M = V, Nb, Ta) surfaces.
• Electronic structure analysis to understand the origin of catalytic activity.

Main Results:

• Co-H₁-V₂CO₂ and Ni-H₁-V₂CO₂ exhibit excellent ORR activity with low overpotentials (0.35 and 0.37 V).
• Fe-H₁-V₂CO₂, Co-V_O-Nb₂CO₂, and Ni-H₂-Nb₂CO₂ show promising OER activity with low overpotentials (0.29, 0.39, and 0.44 V).
• Co-H₂-Ta₂CO₂ demonstrates exceptional bifunctional activity with a low potential gap of 0.53 V.

Conclusions:

• The proposed doping strategy effectively enhances ORR and OER catalytic performance of MXene materials.
• Electronic structure, particularly electron-donating capacity and synergistic effects, dictates the catalytic efficiency.
• These findings provide theoretical guidance for designing advanced 2D MXene electrocatalysts.