Research Areas and Projects

A01 develops very efficient PS–CAT dyads to understand the effects of protecting highly conjugated bridging ligands via rotaxane formation utilizing ultrafast time resolved spectroscopy. This will enable optimization via exchange of the PS to iron-chromophores and exploiting macrocycle mediated substrate pre-activation. Metal mediated alcohol oxidation with nanographene electron reservoirs as a catalytic oxidation reaction will be linked to light induced reduction. Detailed understanding of reaction mechanisms utilizing pulse radiolysis will allow description of complete catalytic cycles.

A03 focuses on the development of noble metal-free, photostable PS, including structures accessible from inexpensive, scalable precursors. These PS will be functionalized for covalent integration into soft matter matrices and thin-film membranes. Noble metal-free PS–CAT dyads will be synthesized and studied in diverse environments to assess charge separation dynamics, catalytic turnover, and photostability. The photocatalytic scope will be expanded beyond hydrogen evolution to include alcohol oxidation.

A04 explores covalently linked PS–CAT dyads and triads with a focus on noble metal-free systems. The dyads will be based on metal complex or organic PS as well as polyoxometalate, thiomolybdate or metal complex HER-CATs. Catalytic performance effects of different linkage groups and electronic communication between the components will be studied. Theoretical modelling of the photophysical dyad properties and potential excited-state reaction pathways will be explored and correlated with experimental observables. Functionalization of the dyad periphery will be used for covalent matrix embedding.

A05 develops molecular synthetic means to control the structure and function of thiomolybdate HER CATs by organo-functionalization and PS–CAT dyad assembly. Ultrafast vibrational spectroscopy and TD-DFT will be used to rationalize light-driven HER activity. In situ / operando mechanistic studies of HER-activity in polymer matrices will be explored in collaboration with B and C projects.

A06 focusses on organic molecular compounds and materials for light-driven catalysis and their mechanistic understanding using optical spectroscopy and transient electron paramagnetic resonance (EPR). It will establish noble metal-free PSs and PS–CAT dyads using the organic donor-acceptor design principle, enable the coupling of oxidative and reductive light-driven catalysis through redox-active soft matter matrices and redox mediation and study the mode of action of organic PS and redox mediators for light-driven catalysis with optical spectroscopy and transient EPR.

A07 leverages the subsequent absorption of photons with different wavelengths to enable coupled half reactions. To this end, quinones (Q) will be used as light absorbers, which are reduced to hydroquinones (QH2) with concomitant water oxidation. The QH2 is in turn excited to release H2 and to regenerate the Q starting state. Appropriate Q/QH2 derivatives will be identified and synthesized for this reaction sequence, and they will be combined with suitable WOC and HER-CATs. Through integration into soft matter matrices and optimal reactor environments, coupled half reactions will be realized.

B02 – DNA origamis will be used for the precise spatial positioning of functional moieties such as molecular compounds (e.g. dyes, photosensitizers, catalysts and electron relays) as well as functional copolymers. We will elucidate structure-property relationships in these assemblies and study energy/electron transfer processes. Precise assembly of two molecular entities on the surface, assembly of molecular moieties next to copolymers, two functional copolymers, which are assembled in close proximity as well as the surface-routing of single functional moieties is developed.

B03 develops and studies the integration of catalytically active polyoxometalates and PS into porous, soft matter materials and subsequent use in light-driven catalysis under flow conditions. For this, we synthesize scalable micro-structured, surface-functionalized 3D printed scaffolds modified by anchoring polyampholytic polymers layers, followed by electrostatic or covalent binding of noble metal-free molecular PS and CATs. Characterization by in situ / operando total reflection and micro X-ray fluorescence analysis will provide a modular toolbox for (coupled) HER and WOC.

B04 develops integrated, asymmetric photoelectrocatalytic nanomembranes that couple light-driven reduction (HER, NAD+-reduction) and oxidation (WOC, AOC) systems within a soft matter architecture mimicing thylakoid membranes. Ultrathin membranes will be fabricated by electropolymerization and functionalized with molecular CAT and PS; nanopores and photoredox-active rotaxanes will enable controlled transfer across ultrathin films. Operando spectroscopic analyses will elucidate the structure-function-stability relationships of these matrices under catalytic conditions.

B06 investigates photo(electro)catalytic systems based on both ionic (PHI) and non-ionic polymeric carbon nitrides (PCNs), targeting control over activity, stability, and selectivity. Mixed and hybrid PCN materials are developed to tailor excitonic and interfacial properties for improved charge separation and transfer. Architectures with strongly rectifying interfaces will be based on PCNs and redoxactive soft matter scaffolds and catalysts. Time-resolved spectroscopy and photoelectrochemical studies will elucidate the interplay between structure, excitonic dynamics, and catalytic function.

B07 will couple two light-driven half-reactions across ultrathin (ca. 1 nm) carbon nano-membranes (CNMs) that transport charged species (H+ and e−) and possess selective permeation of H2, O2 and H2O. After establishing CAT and PS CNMs, we now focus on coupling reductive and oxidative half reactions. New PI Christine Kranz will provide dual-side H2 and O2 detection on free-standing CNMs. Four WPs span material synthesis, localized in situ activity measurements, and light-driven catalysis. The overarching goal is to create Janus-type CNMs that replicate essential thylakoid-membrane functions.

B08 will provide optimal local reaction conditions for water splitting catalysis. Recognizing that the component half-reactions require different conditions, we will use compart-mentalization via lipid bilayer membranes to individually optimize the redox potential and pH for each half reaction. Transport systems, such as transmembrane molecular wires and active proton pumping based on photoacids will be used to control the movement of protons and electrons between compartments to establish the optimal nonequilibrium pH and redox gradients for water splitting photocatalysis.

B09 develops thin molecular membranes with tunable intermolecular interactions for the integration of molecular PS / CAT based on the Langmuir–Blodgett (LB) technique. Tailored amphiphiles are oriented unidirectionally to enable side-selective functionalization with PS / CAT, rendering these an ideal platform for coupling catalysis. To increase stability, the membranes are crosslinked and functionalization with PS / CAT is achieved either by co-embedding or by covalent attachment. This yields macroscopic, light-absorbing thin-film systems that can be produced using roll-to-roll techniques.

B10 develops porous and hybrid polymeric carbon nitrides (CNs) with high surface area and controlled stacking to promote efficient charge separation. Functionalization with molecular PS / CAT and single-atom metal sites will be guided by theory and experiment to tune mid-gap states, exciton dynamics, and charge-transfer pathways. Integration of redox CAT sites will create spatially organized, artificial chloroplast-like photocatalysts. The interplay between photophysics, interfacial reactivity, and scaling relations will be investigated through advanced spectroscopy and advanced simulations.

B11 designs hierarchically porous, functionalized electrospun fiber mats for light-driven catalysis, by either electrostatic or covalent integration of PS/CAT and PS–CAT dyads using copolymers with suitable anchoring groups (bipyridyl, phenanthroline, or click/dynamic covalent groups). Furthermore, we will study the structural and photochemical stability of these hybrid matrices under oxidative conditions (WOC/AOC) and establish strategies to couple reductive (HER) and oxidative (WOC/AOC) half-reactions.

C02 will develop an operando spectroscopy platform that is data-wise interlinked be-tween Jena and Ulm to study PS, CAT, PS–CAT degradation, matrix-controlled reactivity, and coupling of half-reactions. Operando-capable coherent Raman (SRS/CARS) and FLIM will be introduced and integrated into unified reactor setups, enabling 3D chemical imaging of matrices. Multimodal data fusion and AI-assisted analysis will enable kinetic modelling and thus the identification and evaluation of repair strategies.

C03 will explore how light-driven catalytic molecular components embedded in complex materials interact with their explicit environment, including solvents, membranes or matrices. Hybrid quantum mechanics/molecular mechanics (QM/MM) will be exploited to investigate how polymer matrices as well as lipid bilayer membranes with DNA scaffoldings affect structural, electronic, and photophysical properties of selected molecular components. Catalytic mechanisms and possible degradation mechanisms in the presence of the environment will be also studied. Time-resolved studies of energy and electron-transfer processes between donor and acceptor units will be carried out by developing a multi-scale fragment-based excitonic model for excited-state dynamics.

C05 targets multiscale modelling of molecular photocatalysis in soft-matter matrices, focusing on the role of the environment. We aim at describing charge-transfer and charge-carrier separation across membranes, considering PS/CAT embedded in carbon nanomembranes. Specifically, we seek to determine how the local environment and interfacial disorder govern charge separation, transport and catalytic turnover. Close interaction with experimental partners through iterative feedback between simulation and spectroscopy will allow linking microscopic structure and macroscopic function.

C06 aims to comprehend the effect of mass and radiation transport mechanisms during light-driven catalysis to develop reaction engineering control concepts as basis for effectively coupling reaction spaces. An automated screening platform will be established and linked to MBDoE methods. The derived models will be employed to operate reactors under optimal conditions, resulting in improved activity. Tailored reactors for coupling half-reactions and scale-up concepts will be established for natural sunlight operation.

T02 aims to sustainably transfer the core, research-driven content and findings of CATALIGHT into educational institutions (schools, student laboratories, and university teaching). We have identified key barriers that have previously hindered the integration of CATALIGHT-related topics into school education and together with our industrial partner PHYWE we intend to develop innovative, low-cost material sets, experiment systems, teacher and lecturer training programs, and informational resources that specifically address these barriers.