Research team
Expertise
My research focuses on advancing electrocatalytic strategies for the synthesis of chemical energy carriers and value-added products beyond H2 production or CO2 reduction. Specific aspects include the design, implementation, and mechanistic investigation of custom tailored molecular and material-based electrocatalysts, particularly focusing on group 9 and first-row transition metal complexes, metal-organic frameworks, and nanoparticles. These catalysts are developed to mediate atom-economic and energy-efficient electrocatalytic hydrogenation of various organic compounds, including carbonyls, nitriles, unsaturated hydrocarbons, and aromatics, as well as bio-feedstock valorization, anodic electro-epoxidations, C–H oxidations, and nitrogen activation. At ELCAT, I investigate the combination of process and catalyst development with advanced process engineering in flow electrolyzers, to provide solutions that traditional approaches of targeting exclusively either chemical developments or reactor engineering cannot achieve. In situ and ex situ spectro-electrochemical analysis (UV/Vis, EPR, NMR, Raman spectroscopy) guide these developments through mechanistic understanding, helping to assess active catalyst species during in operando scenarios, as well as dynamic ranges of product distributions and intermediates in our processes. Target applications of my research include the development of fully electrified liquid organic hydrogen carrier (LOHC) systems for reversible energy storage and delivery, paired electrolysis setups for co-generation of anodic value-added products instead of OER for the hydrogen economy, and electrified nitrogen fertilizer production with minimal CO2 footprint through innovative processes.
Electro-Organic Synthesis of Energy Carriers & Value-Added Products.
Abstract
This research program considers H2O and electricity as reagents for electro-organic synthesis, aiming beyond simple H2 or O2 evolution. Electrocatalyst design & mechanistic studies are at the focus, to enable H2 gas-free electro-hydrogenations with H2O in one step. As a second project pillar, anodic electro oxygen-atom transfer reactions (e-OAT) are developed as a replacement for the O2 evolution reaction in traditional water splitting, such that value added anodic products can support economic H2 production at the cathode in paired electrolysis. For project pillar 1, direct electro-hydrogenation with H2O in one step eliminates challenging transport and handling of explosive H2. Due to intrinsic waste heat coupling, it is also thermodynamically favored over existing two-step Power-to-X processes that first liberate H2 and then consume it in a subsequent chemical hydrogenation step. Targeted are e-hydrogenation for reversible energy storage in liquid organic hydrogen carriers (LOHCs), for biomass valorization and in circular economy context to recover amines and alcohols by e-hydrogenation of polyamides and polyurethanes. Two strategies guide this work: firstly, known transfer hydrogenation catalysts (e.g. Ir, Co, and Mo pincer complexes) that use isopropanol or formic acid as H-donor are adapted to work as electrocatalysts that use H2O as sustainable H-donor. Secondly, porphyrin CO2 reduction catalysts (molecules and materials) are derivatized to convert organic substrates with selective hydrogenation of C=O bonds over C=C bonds. Model substrates include alkenes, the acetone / isopropanol LOHC system, the bio-feedstock model 5-HMF, and cinnamaldehyde for chemo-selectivity studies. For project pillar 2, electrocatalytic oxygen atom transfer (e-OAT) reactions are developed, harnessing the O-atom of water for value-added product generation (C=C epoxidation & C–H oxidation) at the anode during electrocatalytic H2 production. In contrast to standard OER, this distributes process costs over two products (e.g. H2 and epoxide), reducing the price for green H2 drastically. This is achieved with cytochrome P450-mimicking porphyrin catalysts that generate reactive metal-oxo species by electro-oxidation in water. Parasitic OER is suppressed by catalyst design, tuning of reaction conditions, and mechanistic considerations. As a future perspective, the aim is to harness the atomically precise reactive sites in porphyrin-based MOF and polymer coated electrodes for secondary coordination sphere tuning in materials. As a general aspect that adds uniqueness to the project, the combination of catalyst-, reaction-, and process design in flow electrolyzers is evaluated, to provide solutions that traditional approaches of targeting exclusively either chemical developments or reactor engineering cannot achieve. Methodically this work is driven by molecular and material catalyst design, using mechanistic insight on reactions, to tune key steps that determine energy efficiency and reaction selectivity, particularly to suppress side reactions HER & OER. Spectro-electrochemistry (UV/Vis, Raman, EPR, NMR, & GI-PXRD) and stoichiometric electro-synthesis of active species help elucidate mechanisms. Reaction optimization is supported by design of experiment (DoE), finding cross-correlations of experimental parameters and ideal conditions with mathematic process models, instead of trial and error.Researcher(s)
- Promoter: Halter Dominik
- Fellow: Halter Dominik
Research team(s)
Project type(s)
- Research Project