The biggest contributor to ‘global warming’ is CO2 emission by burning fossil fuels. It is feasible to achieve carbon neutrality by recycling CO2 to fuels, which has a negative carbon footprint. It is not economical to recycle CO2 under the traditional circumstances, which involve extreme conditions. (Photo)-electrocatalytic CO2 reduction using thin-film semiconductor at room temperature is promising. For CO2 reduction, molecular catalysts are beneficial, because of easy structure-function correlations, but they lack recyclability and durability. CO2 reduction catalysts will be produced by the EU-funded MolPPS project through heterogenization of molecular catalysts in porous matrix with 3D crystalline architecture. Due to heterogenization, the proposed catalyst will possess inherent activity and gain stability. MolPPS will help elucidate the principles leading to heterogeneous molecular catalyst designing. This proposal will implement two distinct heterogenization methods for iron/tin porphyrins containing carboxylic acids and hydroxyl groups into porous covalent organic framework. Porphyrins are well-known CO2 reduction catalysts. The microenvironment around porphyrins will be tweaked to tune the (photo-)electrocatalysis to produce methane and formic acid, drawing inspiration from the effects of extended coordination spheres and proton management commonly exploited by the biological enzymes. Electrochemical theories will be expanded to decipher mechanistic information, and develop catalytic models. Working for MolPPS will aid the experienced researcher achieving his goals for an independent research career by: (1) scientific training in organic synthesis and catalysis, (2) mentorship training via supervision of PhD students, (3) fund management training, and (4) develop long-lasting collaborations.

Solar fuels can be synthesized by integrating electrocatalysts with semiconductors, using sunlight to drive endergonic chemical reactions. Employing molecular electrocatalysts allows the tunability, selectivity, and three-dimensional architectures associated with molecular components to be combined with the solar energy capture and conversion properties of solid-state semiconducting materials. However, there is a lack of understanding of how photo-generated carriers are transported through these systems, disfavouring the rational design of efficient photoelectrocatalytic constructs. This proposal aims to interface copper porphyrins with built-in hydroxyl groups, known catalysts for CO2 reduction, to carbon nitride for photo-promoted generation of highly reduced products from CO2, including methane and ethanol. Catalytic activity and selectivity will be studied by using multi-dimensional approaches for porphyrin immobilization, drawing inspiration from the extended coordination spheres crucial in biological tuning of enzymatic activity. This will be achieved through synthesis of three distinct reaction environments at carbon nitride consisting of: a porphyrin monolayer, a polymer film coordinating the porphyrin, and a 2-D highly ordered covalent-organic framework (COF) composed of the porphyrin. It is expected that these specialised environments will give rise to distinct kinetic responses and product distribution. Existing electrochemical models will be extended to this photoelectrochemical data to investigate the interplay of light flux, substrate and electron diffusion, and catalytic rates, leading to the extrapolation of fundamental principles governing interfacial photo-induced charge transfer at catalytic thin films. Through this project, leadership training, language acquisition, and communication skills will be emphasized, furthering the experienced researcher’s career goals and preparing her for an independent career in solar fuels.

The ability to introduce functionality into molecules in a regio- and chemoselective selective manner is of primary importance in the construction of high value molecular compounds but still remains a major challenge for synthetic chemists. The utilization of functionalities present in readily available and inexpensive starting materials to direct the introduction of further complexity is an attractive strategy which has become increasingly popular. Despite recent advances, the remote-functionalization of aliphatic alcohols still remains largely underdeveloped. Considering their prevalence in natural products, compounds displaying important biological activities and chemical feedstocks, efforts to address this problem are deemed necessary. ALCO2-FUNC will make use of an easily installed α bromo-silyl tether to direct functionalization at neighbouring sites. The tether will partake in single electron transfer with a suitable nickel catalyst, initiating a directed radical rebound cascade. The merger of (reductive) nickel catalysis with photoredox catalysis will exploit advantages of both disciplines, enabling the development of a divergent strategy by careful control of key catalytic steps. Furthermore, carbon dioxide will be utilized as a C1 synthon to provide a valuable carboxylation strategy. To such end, simple alcohols will be converted to their β-carboxylated counterparts (via regioselective 1,5 hydrogen atom transfer) or remotely-carboxylated (following a nickel chain-walking sequence). Taken together, the synergy between photoredox and nickel catalysis will be employed in ALCO2-FUNC to develop novel synthetic strategies to access high value compounds from simple precursors. The proposed methodology is expected to operate under mild conditions (room temperature, low-energy irradiation) increasing functional group compatibility and setting the basis for the implementation in the late-stage functionalization of advanced pharmaceuticals.

The unique properties of the carbon-fluorine (C-F) bond explain why organofluorine compounds play a central role in biopharmaceuticals. One current challenge in drug discovery is the selective installation of C-F stereogenicity within the active site of lead candidates, such molecular editing may greatly help in increasing potency and understanding metabolic degradation paths. However, the limited C-F bond formation techniques complicate this approach and providing new versatile catalytic techniques, which can expand the substrate pool amenable to C-F bond formation, would greatly boost the impact of fluorine chemistry in drug discovery. We aim at developing methods that require feedstock materials as substrates, such as alkene and alkane derivatives. The new methods will combine the potential of enantioselective organocatalysis or metal-mediated processes with visible light photocatalysis. The PHOTO-FLUOR project is unique in that it provides training in “enantioselective fluorination” and “catalysis applied to drug discovery”, areas that contribute to European excellence. The resulting techniques may immediately impact the EU Health sector. PHOTO-FLUOR will merge the expertise of the host group in photochemical enantioselective reactions with the background of the applicant in transition metal catalysis, to reach the desired deliverables and milestones. In addition, a secondment at an internationally recognized pharma-company has been included in the work plan for conducting biological study of the fluorine-edited bioactive molecules. The applicant will transfer knowledge to both host groups creating a link between them to forge future collaborations. Finally, an ambitious training program, which includes a number of new scientific and soft skills to be transferred to the applicant, is also envisaged. The multi-cultural nature of this project will greatly broaden the fellow competencies and will place him in an excellent position for the next career move.

A novel concept for a photo-electro-catalytic (PEC) cell able to directly convert water and CO2 into fuels and chemicals (CO2 reduction) and oxygen (water oxidation) using exclusively solar energy will be designed, built, validated, and optimized. The cell will be constructed from cheap multifunction photo-electrodes able to transform sun irradiation into an electrochemical potential difference (expected efficiency > 12%); ultra-thin layers and nanoparticles of metal or metal oxide catalysts for both half-cell reactions (expected efficiency > 90%); and stateof- the-art membrane technology for gas/liquid/products separation to match a theoretical target solar to fuels efficiency above 10%. All parts will be assembled to maximize performance in pH > 7 solution and moderate temperatures (50-80 ºC) as to take advantage of the high stability and favorable kinetics of constituent materials in these conditions. Achieving this goal we will improve the state-of-the-art of all components for the sake of cell integration: 1) Surface sciences: metal and metal oxide catalysts (crystals or nanostructures grown on metals or silicon) will be characterized for water oxidation and CO2 reduction through atomically resolved experiments (scanning probe microscopy) and spatially-averaged surface techniques including surface analysis before, after and in operando electrochemical reactions. Activity and performance will be correlated to composition, thickness, structure and support as to determine the optimum parameters for device integration. 2) Photoelectrodes: This unique surface knowledge will be transferred to the processing of catalytic nanostructures deposited on semiconductors through different methods to match the surface chemistry results through viable up-scaling processes. Multiple thermodynamic and kinetic techniques will be used to characterize and optimize the performance of the interfaces with spectroscopy and photo-electrochemistry tools to identify best matching between light absorbers and chemical catalysts along optimum working conditions (pH, temperature, pressure). 3) Modeling: Materials, catalysts and processes will be modeled with computational methods as a pivotal tool to understand and to bring photo-catalytic-electrodes to their theoretical limits in terms of performance. The selected optimum materials and environmental conditions as defined from these parallel studies will be integrated into a PEC cell prototype. This design will include ion exchange membranes and gas diffusion electrodes for product separation. Performance will be validated in real working conditions under sun irradiation to assess the technological and industrial relevance of our A-LEAF cell.