Synthesis and catalytic properties of Pd nanoparticles loaded nanoporous TiO2 material

In the present work, Pd nanoparticles were loaded on the nanoporous TiO2 material by a simple chemical deposition. The amount of Pd nanoparticles was determined by the loading times. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and chronoamperometry (CA) methods were used to characterize the surface morphology, composition and electro-catalyst activity of the nanoporous Pd/TiO2 material. CV and CA results exhibited the excellent methanol electro-oxidation performance of 6 times loaded sample. The effects of methanol concentration, H2SO4 concentration and upper scan limits on the electro-oxidation performance of six times loaded sample were investigated. In the solution with low methanol concentration, electro-oxidation of methanol was influenced by the amount of methanol molecules on Pd active sites. In the solution with high methanol concentration, electro-oxidation of methanol was controlled by intermediates diffusion. With increasing H2SO4 concentration, driving force of methanol oxidation decreased. However, the increase of bisulfate adsorption, the reduction of thermodynamic tendency and solution conductivity would result in the suppression of peak current density. The upper scanning limit had obvious influence on the active sites for the methanol oxidation reaction in the backward scanning stage. The generation of PdO at high potential was undesired for methanol electro–oxidation