Advanced Catalyst, Ink, and Emulsion Designs for Reductive Organic Electrosynthesis

As industries seek cleaner and more efficient methods of chemical production, electrochemical technologies offer a promising pathway to reduce carbon emissions and dependence on fossil-based processes. In this context, electrochemical synthesis is gaining traction for its potential to decarbonize key sectors such as fuels, chemicals, and materials. Advances in electrochemical synthesis increasingly rely on zero-gap electrolyzers for their scalability, energy efficiency, and compatibility with green chemistry principles. Central to the performance of these reactors is the precise engineering of catalyst inks, electrode interfaces, and electrolyte environments. Achieving such engineering requires rigorous characterization and, critically, the integration of this knowledge into the development cycle, ensuring that performance insights directly inform design and optimization. This thesis, consisting of four studies (Chapters 3 to 6), presents a coherent research path that integrates ink optimization, emulsion engineering, and advanced characterization techniques to drive forward the field of electrosynthetic process development. In the first study, a flexible workflow to innovate and optimize electrode fabrication for electrochemical hydrogenation reactions is introduced. Focusing on the hydrogenation of phenylacetylene in a zero-gap cell, the influence of catalyst ink deposition techniques, substrate choice, catalyst loading, and additive interactions is systematically investigated. To characterize the catalyst inks, analytical centrifugation is employed, offering an effective path to assess sedimentation behavior and thereby inform ink formulation choices. This foundational work establishes reproducible experimental protocols that support data comparability and performance optimization. Building on this, the second study applies the developed workflow to the electrochemical reduction of CO2 using silver-based molecular catalysts integrated into gas diffusion electrodes. Analytical centrifugation again plays a central role, adapted to characterize the stability and dynamics of complex ink formulations beyond conventional particle dispersions. By analyzing solvent-catalyst and solvent-additive interactions across multiple solvent systems, optimal inks that maximize Faraday efficiency (FE) are identified, achieving FEs of up to 67 % at a current density of 600 mA cm-2. This demonstrates how ink engineering, guided by precise analytical tools, enables the transition from laboratory-scale cells to industrially relevant zero-gap configurations. In the third study, the application spectrum of the employed analytical centrifugation methodologies is extended, adapting them specifically for the characterization of emulsions. By validating these methodologies with six model emulsions stabilized by different surfactants, the study shows that the centrifugation-based approach offers quantitative, interpretable insights into emulsion dynamics and stability, which are crucial for formulations used in food, pharmaceutical, and electrochemical applications. Accordingly, this work broadens the analytical scope of the methodology from solid dispersions to include complex multiphase emulsions featuring liquid-liquid interfaces. In the fourth study, this expanded analytical capability is directly applied. Aqueous emulsion-based catholytes are introduced as a greener alternative to volatile organic compounds for the electrochemical hydrogenation of phenylacetylene in a zero-gap cell. Surfactant selection and emulsification protocols are shown to directly affect emulsion stability and catalytic performance. Using the previously introduced methodology, emulsion characteristics are quantified, confirming that conversion can be achieved even without complete substrate solubility. In contrast to solution-based approaches, products can be separated either by centrifugation or via gravity-assisted creaming, thereby reducing the specific energy demand per mole of product by 40 to 60 %. This marks a pivotal innovation in sustainable electrosynthesis, combining zero-gap reactor scalability with simplified downstream processing and reduced environmental burden. Taken together, these four studies establish a coherent and strategically unified scientific framework in which analytical centrifugation is transformed from a single technique into a versatile platform for addressing fundamental challenges in electrosynthesis. By embedding rigorous characterization directly within the development process, this work moves beyond incremental optimization to demonstrate how methodological innovation can actively shape the design of next-generation electrochemical systems. From particle dispersions to the stabilization of complex emulsions, the approach presented here articulates a generalizable framework for the rational engineering of high-performance, low-carbon technologies.