Rational design of ordered Pd-Pb nanocubes as highly active, selective and durable catalysts for solvent-free benzyl alcohol oxidation

The selective oxidation of alcohols is an important chemical process with many potential applications in fine-chemical synthesis, however, the catalysts reported so far generally suffer from low activity and poor selectivity. We present here a class of ordered Pd3Pb nanocubes (NCs) with an intermetallic phase and well-defined surface as unique catalysts for selective oxidation of benzyl alcohol to benzaldehyde. The optimized Pd3Pb NCs exhibit both enhanced activity with the turnover frequency of 191 000 h(-1) and excellent selectivity up to 91.0%, outperforming the Pd3Pb/Pd NCs and Pd3Pb nanoparticles (NPs) as well as Pd NPs. The Pd3Pb NCs show increased activity in the initially consecutive reaction cycles and do not suffer from distinct deactivation thereafter. X-ray photoelectron spectroscopy reveals that the high ratio of Pd2+ to Pd-0 in the surface of Pd-Pb NPs enhances the benzaldehyde productivity, and the electronic modification of the Pd3Pb NCs boosts the benzaldehyde selectivity. Attenuated total reflectance infrared spectra further confirms that the weak benzaldehyde absorption on the Pd3Pb surface results in high selectivity of benzaldehyde.