Scalable and high efficiency materials and reactors for direct solar hydrogen production

Expected Outcome:Facing a period of climate emergency and energy crisis, Europe needs to rethink the energy market with solutions based on renewable sources capable of directly generating renewable fuels. Hydrogen is a valuable energy carrier and an important feedstock for industry, but its production still relies almost exclusively on fossil fuels. The conversion of solar energy into chemicals such as hydrogen is expected to grow in importance as a sustainable energy resource. Especially, thermo-chemical cycles (TCC) or photoelectrochemical/photocatalytic (PEC/PC) water splitting using sunlight represent eco-friendly and promising technologies to produce hydrogen with the possibility to have standalone systems for delocalised production not necessarily connected to the power grid.To date, thermochemical and photo-assisted solar-driven technologies are still in the proof-of-concept stage and face challenges in improving solar-to-hydrogen conversion efficiency to make solar-based hydrogen production competitive. Additionally, R&D in materials should aim to discover novel abundant and cost-effective catalysts and redox materials as well as more integrated process design promises in the respective fields. Development of TCC or PEC/PC reactors is essential along with overcoming challenges related to the efficiency, stability and scalability.TCC processes use high-temperature solar heat to drive redox reactions that decompose water into hydrogen and oxygen through a series of chemical steps. These cycles typically involve metal oxides or non-metal oxides or other chemicals that undergo reversible oxidation and reduction, enabling the splitting of water. Although several materials and cycle configurations have demonstrated feasibility at kW scale, the technology remains at an early stage of development, with key challenges related to redox material stability, reaction kinetics, and efficient heat integration. Experimental systems have shown proof-of-concept operation