Shepherding Reaction Intermediates to Optimize H2 Yield using Composite-Doped TiO2-based Photocatalysts

• Hydrogen photoproduction on multicomponent Pt-TiO2-based catalysts. • Optimization using Zr-doping of anatase and surface decoration by SnSx. • Charge carrier fate analyzed using a multitechnique approach. • Oxygen- and carbon-centered radicals play unexpected roles to control activity. Optimization of Pt-promoted TiO 2 -based is key to promote the photocatalytic production of hydrogen using sacrificial alcohol molecules. Combination of doping and surface decoration of the mentioned base photoactive material is here exploited to maximize hydrogen yield. Using the quantum efficiency parameter, it is shown that the resulting composite system can boost activity up to 7.3 times within the whole methanol:water mixture ratio, yielding quantum efficiencies in the ca. 13–16 % range. The key role of the different components in generating charge carrier species and their use to trigger the sacrificial molecule evolution and control reaction kinetics are examined through an in-situ spectroscopic study. The study unveils the complex reaction mechanism, with generation of C1 to C3 molecules from different carbon-containing radicals, and interprets the physical origin of the huge H 2 production enhancement occurring in doped-composite titania-based catalysts.