Highly stable two-dimensional Fe₃C₁₈ monolayer and its bifunctional catalytic activity

Abstract

The incorporation of metal species into two-dimensional (2D) carbon materials has emerged as a predominant strategy for designing advanced catalytic systems. Nevertheless, conventional metal-carbon hybrid catalysts frequently suffer from limited metal loading capacity and poor structural stability, significantly constraining their practical applications. By first-principles calculations, we predict a novel type of highly stable 2D atomically thin iron-carbon crystal. The designed 2D crystal has a chemical composition Fe₃C₁₈ with both FeC₃ and FeC₄ moieties in one unit cell. We show that the 2D-Fe₃C₁₈ can possibly be fabricated from a self-organizing process upon anchoring Fe atoms on 6,6,12-graphyne. The unique structure of 2D-Fe₃C₁₈ boasts a high Fe loading of 43.7 wt%, and also leads to high stability of the material at a temperature up to 1,000 K. Owing to the different coordination environments, different Fe atoms in 2D-Fe₃C₁₈ exhibit distinct electrocatalytic properties. The FeC₃ moiety is more active than FeC₄ for oxygen evolution reaction while the FeC₄ moiety is a better electrocatalyst than FeC₃ towards oxygen reduction reaction. These studies pave the way for the future design of new functional 2D metal carbides with variable structures.

Keywords

2D metal carbides / single-atom catalysis / bifunctional catalysts / oxygen reduction reaction / oxygen evolution reaction

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