Influence of the morphology of core-shell nanoparticles on the mechanism of organic halide reduction

January 2015 – December 2018
In recent years there has been a growing interest in clean and environmentally friendly methodologies in organic synthesis. To tackle these issues, an electrosynthetic methodology can be applied. Electrochemical syntheses mostly need fewer steps, produce less waste, provide a cheaper reagent and require less auxiliaries. However, a major drawback is that those electrosynthetic processes require very negative electrode potentials what makes them inadequate for use in industrial production processes due to exuberant energy costs. Attempts to reduce the large overpotentials are directed towards improving catalytic activity of the electrode materials. In this research project, the link between the morphology of the catalyst material and the electrosynthetic pathway will be investigated. In a first step, nanoparticles of transition metals will be electrochemically deposited and the effect of their morphological properties (particle size, porosity, …) on the electrochemical syntheses will be studied.

Nanoparticles can be synthesized with high selectivity by means of electrochemical deposition and the nature of the nanoclusters can be tuned by changing electrolyte composition and deposition parameters. In a second step, core-shell electrocatalysts will be constructed with the most active electrode material as a shell metal. These structures consist of a core metal covered with one or few atomic layers of a second shell metal and are of interest because several electronic effects increase their catalytic activity.
As a case study, the mechanism of the electrocatalytic reduction of organic halides  will be unraveled. Due to a strong involvement of the cathode surface in the reaction intermediates, transition metals such as Ag, Cu, Pd, Ni, Pt and Au are selected. Three molecules with a single carbon halogenide bond will be investigated: benzyl chloride, benzyl bromide and benzyl iodide. The different halogen atom substituents in these molecules will indicate the effect of specific adsorption on the electrode surface on the reaction mechanism.