Electron Transfer Reaction Through an Adsorbed Layer

TL;DR

This paper develops a comprehensive formalism for electron transfer through adsorbed layers, covering all coverage regimes and analyzing the effects of adsorbate distribution and coupling strength on current-overpotential behavior.

Contribution

It introduces a unified approach to model electron transfer through adsorbed layers across all coverage levels, incorporating randomness and coupling effects.

Findings

Recovered Marcus inverted region at low coverage.

Observed traditional direct transfer at high coverage.

Analyzed bonding and anti-bonding state effects.

Abstract

We consider electron transfer from a redox to an electrode through and adsorbed intermediate. The formalism is developed to cover all regimes of coverage factor, from lone adsorbate to monolayer regime. The randomness in the distribution of adsorbates is handled using coherent potential approximation. We give current-overpotential profile for all coverage regimes. We explictly analyse the low and high coverage regimes by supplementing with DOS profile for adsorbate in both weakly coupled and strongly coupled sector. The prominence of bonding and anti-bonding states in the strongly coupled adsorbates at low coverage gives rise to saddle point behaviour in current-overpotential profile. We were able to recover the marcus inverted region at low coverage and the traditional direct electron transfer behaviour at high coverage.