Electro-inductive Effects and Molecular Polarizability for Vibrational Probes on Electrode Surfaces

Area of Science:

• Surface science
• Computational chemistry
• Electrocatalysis

Background:

• Designing effective electrocatalytic systems requires understanding electric fields and molecular polarization at interfaces.
• Tailoring molecular structures can influence electronic communication between electrode surfaces and functional groups.

Purpose of the Study:

• To investigate how breaking conjugation affects molecular polarization and vibrational frequencies at electrode interfaces.
• To elucidate the interplay of electro-inductive and through-space electrostatic effects in molecular systems.

Main Methods:

• Utilized variants of 4-mercaptobenzonitrile to systematically alter conjugation pathways.
• Performed periodic density functional theory (DFT) calculations to simulate applied potential dependencies.
• Analyzed CN vibrational frequencies, fractional charge transfer, and orbital occupancies.

Main Results:

• Predicted applied potential dependencies of CN vibrational frequencies consistent with experimental observations.
• Demonstrated that breaking conjugation between the benzene ring and nitrile group had a greater impact on CN frequency response than breaking it at the electrode interface.
• Identified electro-inductive effects dominating continuous conjugation and through-space electrostatics dominating broken conjugation systems.

Conclusions:

• Molecular polarizability significantly influences electrocatalytic behavior.
• The findings highlight the importance of controlling conjugation pathways for tuning electrocatalyst performance.
• Balancing molecular polarizability, electro-induction, and electrostatics is crucial for advanced electrocatalyst design.