Investigation of palladium nanoparticles loaded onto TiO2 nanorod/FTO for enhancement of photoelectro-chemical performance

Abstract

Titanium oxide (TiO2) has been considered as one of the most promising photocatalyst to solve the environmental and energy crisis. The major restriction of TiO2 is the limitation of solar light absorption and high recombination yield of photoelectron-hole pairs. In the present study, TiO2 nanorod arrays (TiO2 NRs) modified with palladium (Pd) nanoparticles showed the improved photoelectrocatalytic activity. TiO2 NRs was synthesized onto FTO glass with a hydrothermal method. Subsequently, fine Pd nanoparticles were evenly loaded on the surface of TiO2 nanorod through a pulsed electrodeposition method, the loading amount and nanoparticle size of palladium nanoparticles could be controlled by changing the deposition pulse cycle during the deposition process. Morphology and composition of the as-prepared sample electrode was characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Photoelectrochemical performance was studied by diffuse reflectance ultraviolet-visible spectrum and photocurrent test. The charge carrier transfer rate was also discussed between bare TiO2 NRs and modified sample through electrochemical impedance spectroscopy and open-circuit potential decay. As for the effect of Pd as the co-catalyst, performance of composite electrode improved along with the loading amount of Pd to reach an optimal value, and then declined with further high Pd amount, which may ascribe to the coverage of Pd onto the surface of TiO2 to block the active site.