Toward a deeper understanding of H-Ni₃C interactions: rule-based insights

Area of Science:

• Materials Science
• Catalysis
• Surface Chemistry

Background:

• Nickel carbide (Ni3C) possesses high catalytic activity for crucial reactions like hydrogen evolution and hydrogenation.
• The precise electronic structure and hydrogen interaction mechanisms on Ni3C surfaces remain insufficiently understood.
• A deeper understanding is needed to optimize Ni3C for catalytic applications.

Purpose of the Study:

• To theoretically elucidate the fundamental rules governing hydrogen atom interactions with Ni3C surfaces.
• To establish a framework for predicting Ni3C surface behavior and catalytic performance.
• To provide insights beyond conventional theoretical models like d-band center theory.

Main Methods:

• Theoretical elucidation of electronic structure and bonding rules.
• Application of resonance structures to predict surface geometries and interactions.
• Analysis of Ni3C surface reconstruction and hydrogen dissociation.

Main Results:

• Established fundamental rules for H interaction: C with formal charge -2/valence 2, Ni-C bond with formal charge +2, Ni2+ valence of 2.
• Derived Ni3C(113) surface reconstruction and correlated Ni-H bonding strength with Ni-C interactions.
• Explained heterolytic hydrogen dissociation on Ni3C surfaces.

Conclusions:

• The study highlights the critical role of metal-carbon covalency in Ni3C catalysis.
• Derived rules enable *a priori* prediction of Ni3C surface behavior with H atoms.
• These findings offer a more accurate interpretation of Ni3C catalytic activity than d-band center theory or current ML potentials.