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Hybrid Materials for Artificial Photosynthesis

Periodic Reporting for period 4 - HyMAP (Hybrid Materials for Artificial Photosynthesis)

Reporting period: 2020-01-01 to 2021-12-31

The main objective of HyMAP is the development of a new generation of multifunctional hybrid photocatalysts and solar photoreactors which allow the exploitation of sunlight energy for the CO2 photoreduction using water as electron donor. This means that only with the 1% of this energy between 12-35 Ton/y·ha of CO2 can be converted into fuels or other useful products. These values will represent an increase of 20 times in comparison with the state of the art and would be higher than the avoided CO2 in bio-ethanol production from corn crops, positioning the Artificial Photosynthesis as a promising CO2 valorisation technology.
The implementation of HyMAP project has been carried out in relation of the work packages proposed in the action. As it was reflexed in the Gantt chart the first work package “Design and synthesis of multifunctional hybrid materials“ is the starting point of the project and therefore it has been much more explored. Both the second and third work packages “Operando characterization and modeling” will allow the fundamental understanding of reaction mechanism and “Evaluation of hybrid photocatalysts in artificial photosynthesis” from laboratory to pilot plant scale with including the design of the next generation of solar photoreactor.

The synthesis of innovative assemblies between inorganic semiconductor oxides and conducting organic polymers was proposed. In this sense, band engineering has been exploited to obtain new inorganic semiconductor formulations. Afterwards, metal SPR-NPs have been supported over these modified systems in order to obtain more effective photocatalysts for artificial photosynthesis under sunlight. With this approach, high selectivities towards hydrocarbons vs. carbon monoxide has been achieved with these metal/semiconductor systems. In addition, commercial conductive organic polymers and organic semiconductors have been incorporated, thus achieving one class of the target organo-inorganic hybrid photocatalysts. These materials have led to an improvement in activity with respect to the purely inorganic systems, but their stability for long-term use is doubtful. Therefore, the HyMAP team has faced the synthesis of new, tailor-made monomers and polymers with the aim of combining high photocatalytic activity with improved stability under reaction conditions. In this respect, conjugated microporous polymers can offer new photoactivities if the selection of monomers from assorted chromophoric units used in their synthesis is adequate, as well as new stability pathways versus the linear ones. The preparation of hybrid assemblies from both organic and inorganic has been carried out successfully. These hybrid modified heterojunctions have improved light absorption, charge separation and photocatalytic activity, and they have also introduced stretchability properties with a view on the development of photocatalytic devices. All of them have been characterized and evaluated as artificial photosynthesis catalysts and in some cases they have overpassed the current state-of-the-art photocatalytic activities.

Moving to a third kind of materials, the rational design and synthesis of new metal organic frameworks (MOFs) with well separated reduction /oxidation active sites as alternative to traditional photocatalysts was explored. At present, the elucidation of the structure of these new MOFs, as well as studies on their implementation as Artificial Photosynthesis catalysts have been described.

During 2020-2021 period one of the main important tasks has been to improve the photocatalytic activity of our new materials focusing in the fundamental understanding of the structure-reactivity relationship. A great effort was realized on the study of the structural and surface catalytic properties under reaction conditions through the use of innovative In-situ and operando characterization techniques including synchrotron techniques.

Finally, the photoreactor and the catalyst conformation are also crucial in this process and numerous technical challenges must be considered. In this sense, HyMAP proposes the design and assembling of solar photoreactor that allow good transmission, uniform distribution and maximize the light harvesting in the overall spectra. Currently, this is the point where the project nowadays is.

The most significant advances will be published in international high impact SCI journals. Important efforts will also be devoted to the scientific dissemination of the most appealing results obtained, trying to communicate and interact with the society. In addition, it would be important to remark that patent applications will be presented when significant advances are achieved with potential industrial scope.
Solar fuels production via artificial photosynthetic processes is a great scientific and engineering challenge due to its complexity. All the approaches described to date open new paths to improve the CO2 photocatalytic reduction, but it is still necessary to develop new catalysts that mimic natural photosynthesis with high enough efficiency so as to consider Artificial Photosynthesis as a viable industrial process. Although there have been considerable advances in the design and synthesis of different multifunctional catalysts based on semiconductors, there are still many fundamental questions to be answered regarding the CO2 valorisation processes. The complexity and lack of knowledge of the role of these new systems in CO2 reduction brings forward the need of performing more theoretical and experimental studies that help to understand the behaviour of the different multifunctional catalysts in the artificial photosynthesis process. In this project, different innovative strategies have been proposed in order to avoid the inherent problems of classical photocatalysts. The results described above represent a step beyond the state of the art in solar fuels production, novel materials synthesis, development of innovative operando characterization tools and the design and built-up of the next generation of solar photoreactors.

This project envisages impacts in different domains, with scientific, environmental, social and economic benefits at a worldwide level.

- Scientific-technological benefits are based in the improvement of the production of solar fuels from CO2 conversion that strongly contribute to the H2020 challenges and those identified by “The Energy Challenge”, related to Low Carbon Technologies with the main objective to develop and bring to market affordable, cost-effective and resource-efficient technology solutions to decarbonize the energy system in a sustainable way, secure energy supply and complete the energy internal market.

- Environmental and health benefits. HyMAP will have a direct impact on reducing the anthropogenic CO2 in the atmosphere and therefore on the fight against climate change that has a direct impact in the environment and health as is summarized in EU challenges and policies, such as: Climate Action, Environment, Resource Efficiency and Raw Materials challenge and Health 2020.

- Economic and social benefits. The combination of technologies presented in this project may have a huge economic potential. Nowadays, worldwide efforts are being devoted to the development of new materials for emerging applications as proposed here. It would be important to remark that application patents will be presented when significant advances are achieved with potential industrials.

From a social point of view, in addition to the benefits related to environment and health, HyMAP will contribute to the socialization of Science, in general, and of the challenges faced in the project, in particular, through intense outreach and dissemination activities in our web-site or other national or international events such as: European Researcher's Night, ERC week, Week of science…