Robust Diamond Electrodes for Electrochemical Applications

Abstract

With one of the widest potential windows of any solid electrode material, boron doped diamond (BDD) has proven excellence as an electrochemical tool. From water treatment and chemical synthesis to electrochemical analysis and sensing, BDD has applications in a variety of sample media. This combined with its’ stability, low background current, and low double layer capacitance make BDD specifically useful in trace detection, such as the determination of toxic heavy metals and polycyclic aromatic hydrocarbons (PAHs) in water. We have developed several BDD electrode technologies, each tailored to a specific electroanalytical application. With a Nafion coated BDD optically transparent electrode (OTE) we engineered a fluorescence based spectroelectrochemical sensor for a common PAH, 1-hydroxypyrene, achieving a detection limit of 80 nM (17 ppb). With this, we fabricated BDD microelectrode arrays (MEAs) for the detection of toxic heavy metal ions where we obtained parts-per-trillion (ppt) detection limits for lead (Pb) using measurements taking no longer than 2 minutes. We also designed and produced BDD rod electrodes for general electroanalytical applications. These BDD rod electrodes exhibit superb electrochemical redox processes where we observed peak separations of 65 mV or less in cyclic voltammetry (CV) of potassium ferricyanide, K3Fe(CN)6. Lastly, we developed BDD electrode stacks for electrochemical oxidation processes including, general TOC/COD reduction, perfluoroalkyl substance (PFAS) degradation, and ammonia (NH3) removal. Near complete removal of PFAS and NH3 from wastewater samples­ was observed. This work further exemplifies BDD as an excellent electrode material while broadening its’ sensing applications and electrochemical capability. Figure 1