Solar hydrogen production from ethanol-water vapours over metal/TiO2 photocatalysts supported on β-SiC alveolar foams

In this work, we have explored the feasibility of alveolar open-cell β-SiC foams as catalyst support for solar hydrogen production. For that purpose, Pt and Ru nanoparticles have been obtained, by means of photoassisted synthesis, on TiO₂-coated foams and tested in gas-phase hydrogen production from water-ethanol mixtures in a tubular reactor coupled to a compound parabolic solar collector (CPC). Subnanometre-sized metal or metal/oxide nanoparticles are obtained for Pt/TiO₂/SiC and Ru/TiO₂/SiC foams, respectively, where co-catalyst nanoparticles decorate the TiO₂ coating which in turn is attached to the SiC foam through an amorphous SiO₂ washcoat formed by SiC pre-calcination. In solar photocatalytic reactions, all of the assayed foam-supported photocatalysts are active for the production of hydrogen, with Pt/TiO₂ ones being the most active and foam pore size exerting little influence on hydrogen outcome. In the best conditions, 14 % UV-to-hydrogen (equivalent to 0.49 % solar-to-hydrogen) conversion efficiency, with photonic efficiency higher than 30 %, is attained.