Proton-coupled electron transfer in molecular electrocatalysis: theoretical methods and design principles

Area of Science:

• * Molecular electrocatalysis for energy conversion.
• * Theoretical chemistry and computational methods.

Background:

• * Molecular electrocatalysts are crucial for energy conversion processes.
• * Electrocatalyst design aims to increase turnover frequency and decrease overpotential.
• * Proton-coupled electron transfer (PCET) is central to electrocatalytic cycles.

Purpose of the Study:

• * To investigate mechanisms, thermodynamics, and kinetics of PCET in electrocatalysis.
• * To guide the design of more effective molecular electrocatalysts through theoretical insights.

Main Methods:

• * Employing electronic structure methods to calculate reduction potentials and pKa values.
• * Generating thermodynamic schemes, free energy pathways, and Pourbaix diagrams.
• * Calculating rate constants for electron transfer, proton transfer, and concerted PCET.

Main Results:

• * Theoretical calculations identify thermodynamically and kinetically favorable mechanisms.
• * Revealed linear correlations between thermodynamic properties and molecular modifications.
• * Demonstrated that concerted PCET, especially with intramolecular proton transfer, can lower overpotential.

Conclusions:

• * Theoretical methods are essential for interpreting experimental data in electrocatalysis.
• * Computational insights aid in designing molecular electrocatalysts with improved performance.
• * Tuning substituents and ligands, and promoting flexible ligand design, are key strategies.