Orbital Dependence in Single-Atom Electrocatalytic Reactions.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Transition metal single-atom catalysts (TM-N-C) offer a model for studying orbital effects in electrocatalysis due to discrete single-atom orbitals.
• Oxygen evolution reaction (OER) is crucial for energy conversion technologies but requires efficient catalysts.

Purpose of the Study:

• To investigate the catalytic efficiency of Fe-N-C for OER using density functional theory (DFT).
• To understand how the local environment of single atoms influences catalytic reactivity.
• To identify the key electronic descriptors governing OER performance.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Simulations focused on Fe-N-C catalysts under varying local environments.
• Analysis involved correlating electronic structure with OER catalytic activity.

Main Results:

• Subtle changes in the single atom's local environment significantly modulate catalytic reactivity for OER.
• The energy level of the transition metal (TM) d orbital center is the primary factor, not the d-band center, in determining OER efficiency.
• The d-band theory can be extended to the sub-d orbital level for predicting catalytic performance.

Conclusions:

• The d orbital energy level is a critical descriptor for OER catalysis in TM-N-C systems.
• Small perturbations, such as lattice strain or atomic displacement, can tune sub-d orbital energies and thus catalytic activity.
• This work provides insights into designing advanced single-atom catalysts by controlling the local electronic structure.