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

Abstract

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 Pd⁰ 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.