Pd-Sn promoted NbOx/TiO2 catalysts for hydrogen photoproduction: Effect of Pd-Sn interaction on charge handling and reaction mechanism

Enhanced performance of Pd in the photocatalytic production of green hydrogen from methanol:water mixtures is achieved through the use of a sn-containing binary co-catalyst. For a Pd:Sn molar ratio of 1:1, the binary co catalyst leads to an outstanding enhancement of activity under UV, visible and sunlight illumination, rendering a quantum efficiency value of 4 % in the latter case. A core-shell type interaction occurs between Pd metal nanoparticles and Sn oxo-hydroxyde nanoentities, resulting in an electronic modification of both components. The chemical effects of the binary co-catalyst were explored under reaction conditions using infrared spectroscopy. Overall, this study provides evidence that the electronic interaction between Pd and Sn promotes the adsorption and attack of the charge carrier species on the methanol molecule and controls the reaction mechanism, favoring the generation of hydrogen. This new system appears to be a strong candidate in the contribution to the new hydrogen economy through a green and eco-efficient process using renewable energy and reagents.