Solvent influence on non-adiabatic interfacial electron transfer at conductive oxide electrolyte interfaces

Area of Science:

• Electrochemistry
• Materials Science
• Physical Chemistry

Background:

• Interfacial electron transfer (ET) is crucial for devices like solar cells and sensors.
• Understanding ET kinetics at conductor-electrolyte interfaces informs material design and device performance.

Purpose of the Study:

• To quantify interfacial electron transfer kinetics from ITO to molecular acceptors.
• To investigate the influence of distance and electric double layer (EDL) structure on ET.
• To determine key ET parameters like rate constant, reorganization energy, and electronic coupling.

Main Methods:

• Nanosecond absorption spectroscopy was employed to measure ET kinetics.
• Variable distances between ITO and molecular acceptors (TPA, RuP) were established.
• Measurements were conducted in benzonitrile and methanol as a function of thermodynamic driving force (-ΔG°).

Main Results:

• Electron transfer rate constant (k_et) increased as the distance to the conductor decreased.
• For molecules within the EDL's Helmholtz planes, k_et was largely independent of -ΔG°, indicating minimal reorganization energy (λ).
• Rips-Jortner analysis confirmed a non-adiabatic ET mechanism with weak electronic coupling (H_ab < 1 cm^-1).

Conclusions:

• The conductor-electrolyte interface significantly lowers the barrier for electron transfer.
• Distance and EDL structure are critical factors modulating interfacial ET rates.
• The findings provide insights into optimizing charge transfer processes at conductive oxide interfaces.