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Molecular Strategies to Modulate the Electrochemical Properties of P‑Type Si(111) Surfaces Covalently Functionalized with Ferrocene and Naphthalene Diimide
journal contribution
posted on 2019-12-12, 15:44 authored by Arindam Mukhopadhyay, Brianna Bernard, Kaixuan Liu, Victor Paulino, Chuan Liu, Carrie Donley, Jean-Hubert OlivierThe surface coverage and molecular composition of redox-active
molecules anchored on conductive surfaces regulate the kinetic and
thermodynamic parameters of charge transfer reactions, providing a
means to tune the electrochemical properties of hybrid materials.
Herein, anchoring strategies and structural properties of redox-active
probes, derived from ferrocene (Fc) and naphthalene diimide (NDI),
are shown to regulate the electrochemical properties of functionalized
p-doped Si(111) surfaces. Covalent functionalization of hydrogen-terminated
Si(111) surfaces with Fc and NDI affords redox-active hybrid interfaces
characterized through microscopy, spectroscopy, and voltammetry methods.
Molecular design and synthetic grafting strategies modulate the electrochemical
properties of the Fc-functionalized Si surfaces with a much higher
(ca. 25 times) surface coverage (1.25 × 10–10 mol cm–2) for one-step photografting compared
to divergent synthetic routes. Interestingly, the thermal grafting
of an alkadiyne followed by “click” reaction with ferrocenyl–azide
leads to one of the highest surface coverages (9.97 × 10–10 mol cm–2) of organo-iron reported
and a significant anodic shift of the half-potential (>350 mV)
compared
to photografting methods. Similar experiments with NDI units exhibited
electrochemical properties that diverge from those recorded for NDI
in solution. The results presented herein offer access to novel redox-active
Si interfaces that evidence tunable electrochemical properties of
potential interest for microelectronic applications.