Atomistic catalyst polarization stemming hydrogen generation from CH4

TL;DR

This study uses DFT calculations to explore how atomic-scale catalyst polarization influences methane dehydrogenation on various surfaces, revealing the role of catalyst charge and electric fields in reaction dynamics.

Contribution

It uncovers the atomistic polarization mechanisms in catalysts involving adatoms and vacancies, linking charge distribution to catalytic activity during methane dehydrogenation.

Findings

Catalyst polarization raises valence band via bond contraction.

Reactant bond elongation is influenced by MP-V interactions.

Catalytic activity correlates with charge of MP-V and local electric fields.

Abstract

As the extremely-sized nanocrystals and nanopores, an adatom M and atomic vacancy V exhibit extraordinary capability of catalysis with however little knowledge about the catalyst-reactant interfacial bonding dynamics. With the aid of DFT calculations, we examined the dehydrogenization of a single CH4 molecule catalyzed using the Rh(111,100), W(110), Ru(0001) surfaces, and monolayer graphene, with and without M or V. It is uncovered in the following three components: (i) catalyst polarization due to atomic under- or hetero-coordination raises the valence band of the catalyst by bond contraction and atomistic dipolar MP and vacancy dipolar V formation; (ii) reactant bond elongation by the interplay of the MP-V = H attraction and MP-V = C repulsion with the = denoting the negative pole of the MP-V; and (iii) reactant conversion, i.e., the scale of H-C elongation, the catalyst valence-band shift, the adsorption energy, and the catalytic activity are proportional to the charge quantity of the MP-V whose local electric field matters.