Teitsworth Taylor S, Fang Hui, Harvey Alexis K, Orr Andre D, Donley Carrie L, Fakhraai Zahra, Atkin Joanna M, Lockett Matthew R
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
Langmuir. 2024 Aug 16. doi: 10.1021/acs.langmuir.4c01787.
Aryl diazonium electrografting is a powerful method for imparting molecular functionality onto various substrates by forming a stable carbon-surface covalent bond. While the high reactivity of the aryl radical intermediate makes this method fast and reliable, it can also lead to the formation of an insulating and disordered multilayer film. These thick films affect electrochemical performance, especially for semiconductor substrates used in photoelectrochemical applications. We studied the effects of film thickness and composition by electrografting in situ-generated aminobenzene diazonium salts onto both n-type and p-type silicon electrodes at fixed potentials. Next, we attached ferrocene to the amine-terminated films and probed their (photo)electrochemical behavior. Cyclic voltammetry measurements showed decreased electrochemical reversibility with increasing diazonium film thickness; this reversibility was restored when ferrocene was incorporated throughout the film with a layer-by-layer deposition process. Finally, we compared the behavior of dark p-type electrodes to n-type photoelectrodes and observed differences in the electrochemical reversibility that we attribute to the change in potential drop across the two interfaces.
