Carbon optically transparent electrodes (C-OTEs) are a stable and efficient spectroelectrochemical platform for detailed study of electrochemical processes and interfaces. This poster displays two examples of C-OTEs based on pyrolyzed photoresist films (PPFs) as improved platforms for studying electrochemical systems. We have utilized these electrodes for oxidative-reductive electrogenerated chemiluminescence (ECL) that display a low oxidation potential for co-reactant ECL as the hydrophobic electrode surface facilitates adsorption of coreactants to generate intense ECL. Furthermore, the PPF generated C-OTEs exhibit wide electrochemical windows of stability and high optical transparency in the UV region (> 35% transmittance over 190-400 nm, and 45-61% for 400-1000 nm for the thinnest C-OTEs of 11 nm thickness). The C-OTEs perform favorably versus ITO in both oxidative-reductive and reductive-oxidative ECL studies, and are observed to be more stable in both acidic and alkaline solutions. We demonstrate how C-OTEs can be used to study the formation of electrogenerated graphitic oxides (EGO) using a combined UV-Vis spectroelectrochemical approach. Monitoring the p-p* aromatic carbon transition for reduced graphene oxide (rGO) at 270 nm and graphene oxide at 230 nm, we follow the growth of GO in KCl upon applying oxidizing potentials. X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (TOF-SIMS) are used to confirm sample composition and location of salt ions within the electrode. Formation of EGO is stable enough to be observed by UV-Vis and a new mechanism is established that is unique to alkali chloride supporting electrolytes due to formation of a solid-electrolyte interphase (SEI) which incorporates the alkali cation to stabilize the negatively charged oxygen functional groups while the presence of chloride anion acts as a passivation agent that protects the electrode surface from dissolution. This spectroelectrochemical approach highlights the detection and study of electrochemical processes that cannot be detected by electrochemical measurements alone.

Spectroelectrochemical studies utilizing carbon optically transparent electrodes (C-OTEs)

246th National Meeting (2013)

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