Structure–activity relationships in metal/TiO2 photocatalysts for hydrogen production via glycerol photoreforming

Photocatalytic hydrogen production via glycerol photoreforming was investigated using M/TiO 2 catalysts (M = Pt, Au, Cu, Co, Fe, Zn). The influence of metal identity, synthesis method (deposition–precipitation vs. impregnation), and reductive pretreatment was systematically evaluated. Noble metals (Pt, Au) showed the highest activity, increasing hydrogen evolution by two orders of magnitude, while Cu emerged as a promising low-cost alternative. Catalysts prepared by deposition–precipitation exhibited smaller, more homogeneous nanoparticles and superior performance compared to impregnated samples. For Pt systems, reductive pretreatment significantly boosted activity by removing residual chloride poisons from the precursor. Mechanistic analysis via H 2 /CO 2 ratios revealed that metallic cocatalysts shift the initial reaction pathway toward glycerol dehydrogenation, whereas bare TiO 2 favors early C–C bond cleavage. These results highlight that optimizing cocatalyst dispersion and surface cleanliness is critical for enhancing charge separation and proton reduction efficiency in sustainable hydrogen production.