Leveraging Interlayer Interaction in M-N-C Catalysts for Enhanced Activity in Oxygen Reduction Reactions

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Atomically dispersed metal-nitrogen-carbon (M-N-C) materials are key catalysts for the oxygen reduction reaction (ORR) in fuel cells.
• The multilayer nature of M-N-C catalysts has been underappreciated in computational studies.

Purpose of the Study:

• To investigate the impact of bilayer M-N-C structures on ORR activity using first-principles calculations.
• To understand how interlayer interactions influence catalytic performance and overpotential.

Main Methods:

• Utilized first-principles calculations on bilayer M-N-C models (TMN_x/G-TMN_y/G, where TM = Mn, Fe, Co, Ni, Cu and G = graphene).
• Analyzed the effect of in-plane versus out-of-plane configurations of the bottom layer on the top active site.
• Performed constant potential calculations to assess voltage dependence of OH binding energy.

Main Results:

• Out-of-plane TMN₃ configurations in the bottom layer significantly impact OH adsorption free energy via interlayer bonding.
• Leveraging these interlayer interactions reduced the ORR overpotential for CoN₄, NiN₄, and CuN₄ active sites.
• A minimum overpotential of 0.40 V was achieved on a CoN₄/G-CuN₃/G model.
• OH binding energy showed weak dependence on external voltage in constant potential calculations.

Conclusions:

• Interlayer interactions in multilayer M-N-C materials are crucial for optimizing ORR catalysis.
• Out-of-plane configurations offer a new avenue for designing high-performance M-N-C catalysts.
• Computational insights into multilayer effects can guide the development of advanced fuel cell catalysts.