Photoelectrocatalysis of Rhodamine B and Solar Hydrogen Production by TiO₂ and Pd/TiO₂ Catalyst Systems

There has been extensive research on the modifications of TiO₂, the most heavily investigated photocatalyst, to improve its lack of visible light harvesting and fast electron and hole recombination rate. Metal loading is one of most common ones that focus on enhancing light absorption and efficient charge separation. Here, a hybrid Pd/TiO2 photocatalyst system was developed where metallic Pd nanoparticles were photochemically deposited onto TiO2 nanorods. The photoelectrochemical performance of the bare TiO2 and hybrid Pd/TiO2 samples were compared through the decolourisation of a standard commercial textile dye Rhodamine B (RhB) and solar hydrogen production in different electrolyte solutions at various applied voltage values. The results are discussed proposing possible reaction mechanisms with an emphasis on the charge trapping role of Pd nanoparticles. The discussions are supported by detailed measurements of Mott-Schottky plots, electrochemical impedance spectroscopy and j-v curves with shifts in the flat band and onset potentials after the deposition of Pd nanoparticles.