Intrinsic Coordination Architecture Governing Selectivity Divergence Between Extended and Single-Site...

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical transformations like CO2 and nitrate reduction show varying selectivity based on material architecture.
• Thermodynamic descriptors often fail to explain selectivity differences across distinct material classes.

Purpose of the Study:

• To identify a key structural factor governing selectivity bifurcation in electrochemical reactions.
• To establish a general framework explaining how coordination geometry influences reaction pathways.

Main Methods:

• Development of a coordination-constraint framework.
• Analysis of intermediate stabilization via multi-atom coordination (ensemble effects) on extended surfaces.
• Comparison of reaction pathways on extended surfaces versus single-atom/molecular sites.

Main Results:

• Extended surfaces stabilize intermediates through ensemble effects, favoring fully deoxygenated products (e.g., ethylene, ammonia) by constraining hydrogenation access.
• Single-atom and molecular sites, with unilateral coordination, expose reactive centers, enabling oxygen-retaining products (e.g., methanol, hydroxylamine).
• Coordination geometry dictates accessible pathways, while electronic/electrochemical factors govern energetics and kinetics.

Conclusions:

• Local coordination geometry is a critical determinant of electrocatalyst selectivity.
• This geometric effect, combined with electronic and interfacial factors, provides a principle for designing selective electrocatalysts.