Electrooxidation

Electrooxidation is an electrochemical process in which oxidation of species in a solution occurs at an electrode under an applied electrical potential. In most cases the reaction takes place at the anode, where electrons are removed from the substrate. Direct electrooxidation involves the substrate transferring electrons directly to the electrode, while indirect electrooxidation proceeds via oxidants generated at the electrode surface, such as hydroxyl radicals or other reactive oxygen species. A common example is the oxidation of water to evolve oxygen at high potentials, but the method is widely used to oxidize organic and inorganic pollutants as well.

Mechanisms and materials are central to electrooxidation. The rate and outcome depend on whether the substrate reacts directly with the electrode or with electrochemically produced oxidants. Electrode materials greatly influence performance; boron-doped diamond (BDD) electrodes and metal oxide coatings (for example RuO2 or IrO2) are often used for their high oxygen-atom transfer activity and chemical stability. Carbon-based electrodes and other conductive supports are also employed. The process is sensitive to current density, electrode surface area, solution pH, and the presence of catalyst or mediators.

Cell design and operating conditions vary. Electrooxidation can be performed in divided or undivided cells, with supporting electrolytes to maintain conductivity. Parameters such as potential, current, and residence time are adjusted to optimize mineralization or selective oxidation while minimizing energy consumption and unwanted byproducts.

Applications include wastewater treatment, degradation of dyes and pharmaceuticals, and the synthesis of value-added chemicals through anodic oxidation. Advantages include the use of water as the oxidant and the potential for complete mineralization; limitations involve energy intensity, electrode wear, and the possible formation of undesired byproducts (for example, chlorinated species in chloride-containing solutions).