Novel carbonyl iron-mediated synthesis of Pd–Fe magnetic nanomaterials: mechanism and catalytic performance in Suzuki coupling

Abstract

Palladium–iron (Pd–Fe) bimetallic catalysis represents a pivotal strategy for advancing the sustainability of organometallic transformations. Herein, we report a facile and efficient synthetic protocol for Pd–Fe magnetic nanomaterials mediated by carbonyl iron, which proceeds without external reducing agents, surfactants or protective gases. In this approach, carbonyl iron serves a dual role as both the iron source and the reducing agent, while in situ generated carbon monoxide provides three essential functions: atmospheric protection, pressure regulation and crystal nucleus stabilization. This unique reaction system facilitates the co-deposition of zero-valent palladium (Pd0) and iron oxide (Fe2O3) onto pristine Fe3O4 surfaces, yielding magnetically recyclable Pd–Fe@Fe3O4 nanocomposites. Comprehensive characterization via high-resolution transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping and X-ray photoelectron spectroscopy confirms the well-defined hierarchical structure, uniform elemental distribution and controlled valence states of the as-synthesized materials. The resulting nanomaterials display a narrow particle size distribution (2–3 nm), high metal loading efficiency and low lattice mismatch. Preliminary catalytic evaluations reveal excellent activity of Pd–Fe@Fe3O4 in Suzuki–Miyaura cross-coupling reactions. Notably, similar performance is achieved with catalysts derived from other metal carbonyl precursors, underscoring the generality of this synthetic platform for designing efficient and recyclable bimetallic nanocatalysts.