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

The selectivity of H2O2 synthesis directly from H-2 and O-2 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 CODRIFTS and XPS results. The average size of Pd particles (d(Pd): similar to 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 H-2 > O-2 > N-2, 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.