Elucidating oxidative processes in solution and electrode interfaces using Raman spectroscopy
In his dissertation, Maurits de Roo investigates oxidation reactions, which are important chemical processes in the production of pharmaceuticals, cleaning agents, perfumes, and plastics. These reactions are often made faster and more selective through the use of catalysts that contain precious metals such as platinum or palladium. Because these metals are scarce, expensive, and environmentally harmful to extract, this research focuses on alternative catalysts based on more abundant metals such as iron. De Roo's thesis centers on the iron complex catalyst (N4Py)Fe, inspired by the structure of the natural product and anticancer drug iron-Bleomycin. Using multi-spectroscopic measurements and reaction modeling, De Roo found that an excess of the oxidant hydrogen peroxide leads to its complete decomposition into oxygen and water. In contrast, when using another oxidant, phenylperacetic acid, the catalytic reactions proceed in a completely different way, suggesting the formation of a highly reactive catalytic state that has not been observed before.
Additionally, De Roo studied electrochemistry, where electricity is used to drive chemical reactions. This approach offers a more sustainable alternative to using chemical oxidants for activating catalysts such as (N4Py)Fe. However, studying electrochemical processes is highly challenging, as the reaction layer is about one hundred thousand times thinner than a human hair. To investigate these ultrathin reaction layers, De Roo combined high-speed Raman spectroscopy with surface enhancement—a technique known as electrochemically surface-enhanced Raman spectroscopy. The dissertation further explores the challenges and opportunities of applying this technique to study the electrochemistry of catalysts.