Modification of Electrode Surfaces Via Chromium Deposition [Capital University]

Abstract

Microelectrode arrays are useful in electrochemical detection, having the advantage of lower signal to noise ratios compared to traditional sized electrodes. However, they can be expensive and complex to produce. A cheap, easy to produce, and renewable method of preparing microelectrode arrays in an undergraduate laboratory is therefore highly valuable. This project explores the efficacy of producing a random-microelectrode array by partial deposition of chromium onto an electrode surface, enhancing the study of electrochemistry in undergraduate laboratories. This study uses gold, platinum, and glassy carbon electrodes, ruthenium hexamine as a model electron acceptor, and K2Cr2O7 solution as a chromium source. Current results have produced evidence of microelectrode formation. All electrodes have been completely and partially inactivated by chromium deposition via reduction of Cr(VI) to Cr(III) and can be reactivated electrochemically as well. Deposition is achieved through direct current potential amperometry (DCPA) and illustrated through both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). CVs reveal reduction and oxidation of ruthenium hexamine with uncovered electrodes and a loss of reduction and oxidation with chromium covered electrodes. DPVs reveal similar results. The partial deposition that has been achieved can be difficult to replicate and varies with the electrode material. Background CV scans differ in active and inactivated electrodes, suggesting that capacitance varies with deposition. By measuring capacitance compared to deposition, insight regarding electrode coverage may be found. Experiments aimed at replicating published material on microelectrode production (Anal. Chem. 2016, 88, 1753-1759) are also being performed to demonstrate similarities between results. Comparison to published work and refined methodology is needed to provide strong, reproducible evidence of random-microelectrode array production.