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Reproducible flaws unveil electrostatic aspects of semiconductor electrochemistry.

Nature communications (2017-12-14)
Yan B Vogel, Long Zhang, Nadim Darwish, Vinicius R Gonçales, Anton Le Brun, J Justin Gooding, Angela Molina, Gordon G Wallace, Michelle L Coote, Joaquin Gonzalez, Simone Ciampi
ABSTRACT

Predicting or manipulating charge-transfer at semiconductor interfaces, from molecular electronics to energy conversion, relies on knowledge generated from a kinetic analysis of the electrode process, as provided by cyclic voltammetry. Scientists and engineers encountering non-ideal shapes and positions in voltammograms are inclined to reject these as flaws. Here we show that non-idealities of redox probes confined at silicon electrodes, namely full width at half maximum <90.6 mV and anti-thermodynamic inverted peak positions, can be reproduced and are not flawed data. These are the manifestation of electrostatic interactions between dynamic molecular charges and the semiconductor's space-charge barrier. We highlight the interplay between dynamic charges and semiconductor by developing a model to decouple effects on barrier from changes to activities of surface-bound molecules. These findings have immediate general implications for a correct kinetic analysis of charge-transfer at semiconductors as well as aiding the study of electrostatics on chemical reactivity.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ammonium sulfite monohydrate, 92%
Sigma-Aldrich
1,8-Nonadiyne, 98%