Optimization of Active Sites in TiO ₂ –Cu Photocatalysts for H ₂ Generation via Cellulose Photo‐Reforming

Abstract The study pursues the optimization of active sites in TiO 2 ‐based photocatalysts modified with copper for hydrogen production via cellulose photo‐reforming. Copper was incorporated, by impregnation, in the commercial titania P25 and in hydrothermally synthesized TiO 2 which has a larger surface area and contains only anatase. The hydrothermal synthesis method was also employed for the one‐pot preparation of TiO 2 –Cu photocatalysts. The effect of the copper loading was investigated in the three series of samples. Characterization techniques, including XPS, XRD, UV–vis, and PL spectroscopy, confirmed structural and electronic modifications induced by Cu incorporation, which would directly influence the photocatalytic efficiency. The activity tests demonstrated a significant enhancement in H₂ evolution upon Cu loading, being the photocatalysts prepared by the one‐pot method the most active ones for hydrogen generation, with the highest H 2 /CO 2 ratio and leading to the highest concentration of sugars and organic acids in solution, compared with the catalysts prepared by impregnation. The superior performance of these photocatalysts has been attributed to their increased surface area that allows a higher Cu loading with optimised distribution of active sites. In particular, the catalysts with 3 wt% Cu is the one exhibiting the highest efficiency, producing 2752 µmol·h⁻¹·g cat ⁻¹, and being recyclable.