Single-step in situ synthesis of bimetallic catalysts via a gas-phase route: the case of PdZn–ZnO

Abstract

In this study, we explore the catalytic activity of highly pure PdZn–ZnO nanopowder, synthesized via an innovative metal–organic chemical vapor synthesis (MOCVS) method. Unlike conventional methods that require post-synthesis treatments, this rapid, solvent-free synthesis produces a bimetallic nanocatalyst with a high surface area (S_BET ∼ 110 m² g⁻¹) directly. X-ray diffraction (XRD) confirmed its high crystalline quality, identifying only PdZn-specific diffractions alongside the ZnO phase. High-resolution transmission electron microscopy (HRTEM) analysis revealed a single family of planes with an interplanar distance corresponding to PdZn (111) planes. Furthermore, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy using CO as a probe molecule (FTIR-CO), both conducted under ultra-high vacuum (UHV) conditions, unequivocally confirmed the presence of PdZn entities on the ZnO support. The catalytic performance of this one-step synthesized PdZn bimetallic catalyst was evaluated in the reduction of nitroarenes and hydrodebromination of arylbromides. The catalyst exhibited excellent activity in both reactions, with remarkable recyclability for the reduction of nitroarenes. Additionally, no significant decrease in yield was observed during scale-up tests. This study introduces a novel one-step approach for synthesizing bimetallic nanopowders, which can serve as highly active catalysts and model systems for surface science studies.