Dispersing Pd nanoparticles on N-doped TiO2: a highly selective catalyst for H2O2 synthesis

Abstract

The selectivity of H₂O₂ synthesis directly from H₂ and O₂ over Pd/TiO₂ catalysts was found to be improved greatly if TiO₂ was doped by nitrogen before dispersing the Pd nanoparticles. The structure of Pd catalysts supported on different N-doped TiO₂ was characterized with the combination of XRD, TEM, in situ CO-DRIFTS and XPS results. The average size of Pd particles (d_Pd: ∼2.2 nm) showed no discernible differences, while the chemical states of Pd atoms changed significantly over Pd/N–TiO₂ treated in different atmospheres. The reaction rate decreases in the order of H₂ > O₂ > N₂, corresponding to the same increasing order of Pd²⁺/Pd. Likely, dispersing Pd nanoparticles on N–TiO₂ should be an effective way to tune the interface structure of Pd/PdO, which acts as the active site for H₂O₂ synthesis.