Preparation and Application of Chemically Modified Electrodes with Redox Active Compounds

My research as a postdoctoral associate in Professor Mark S. Wrighton’s lab at the Massachusetts Institute of Technology focused on the synthesis, characterization and catalytic applications of various electrode surfaces modified with redox active compounds. One project exploited the redox properties of a p-quinone (2-chloro-1,4-naphthoquinone) to electrocatalyze the reduction of O2 to H2O2. Surface derivatization (Pt, W, p-WS2 electrodes) with a 1,4-naphthoquinone molecule containing a -Si(OCH3)3 group produced durable and robust electrocatalysts. The [QH2]surf reacts with 02 in aqueous electrolyte at pH 7 to form H202 and [Q]surf. H2O2 was generated electrochemically using a flow system containing high surface area oxides (Si02, A1203) modified with the quinone [MxO]-(Q) and a redox mediator at low concentrations in solution. The production of H2O2 also was demonstrated using a photocathode. Reduction of [Q]surf or mediator at visible light illuminated p-WS2 resulted in the uphill formation of H202 from the quinone-mediated reduction of 02 at an electrode potential ~0.8 V more positive than at a metallic electrode. A patent was adwarded for this process. I also developed a method for covalently attaching derivatives of redox active N,N,N',N'-tetraalkyl-1,4-benzenediamine on electrode surfaces. Representative and informative articles on our studies are listed below.