Switchable molecular electrocatalysis

Area of Science:

• Molecular electrocatalysis
• Coordination chemistry
• Electrochemical energy conversion

Background:

• Ligand design is crucial for controlling catalytic activity in molecular electrocatalysis.
• Understanding structure-activity relationships is key to developing efficient electrocatalysts.
• Hydrogen bonding interactions can significantly influence electronic properties and reactivity.

Purpose of the Study:

• To demonstrate a switchable electrocatalysis mechanism modulated by ligand geometry and hydrogen bonding.
• To investigate the selective activation/deactivation of electrochemical processes at a single catalytic site.
• To explore the distinct roles of different ligand geometries (α and β) in dioxygen electroreduction (ORR) and hydrogen evolution (HER).

Main Methods:

• Synthesis and characterization of metal complexes with varying ligand geometries.
• Electrochemical studies to evaluate catalytic activity for ORR and HER.
• Computational analysis to understand the electronic effects of ligand geometry and hydrogen bonding.

Main Results:

• The α geometry selectively enhances 4-electron ORR by increasing electron density at the catalytic center via intramolecular hydrogen bonding.
• The β geometry promotes 2-electron ORR and facilitates HER through proton charge assembly.
• Contrasting reactivity observed between α and β geometries challenges conventional electrocatalytic principles.

Conclusions:

• Ligand geometry is a powerful tool for controlling electrocatalytic pathways, offering switchable mechanisms.
• Hydrogen bonding plays a critical role in modulating electron density and catalytic performance.
• This work provides a new paradigm for designing selective molecular electrocatalysts for energy applications.