Ligand-Sharing-Mediated Synthesis of Intermetallic FeM Clusters Embedded in Ultrathin γ-Fe2O3 Nanosheets

Precious metal intermetallic nanoclusters (IMNCs) are promising nanocatalysts for practical industrial applications. However, to date, the preparation of these nanoclusters has been restricted to harsh conditions, and only succeeds for a limited number of elements. This study developed a simple and efficient strategy that enables the synthesis of supported IMNCs under ambient conditions via inorganometallic coordination chemistry, specifically, by donating the Cl- ligand, a noble metal chloride (MClab-) forms a heterobimetallic ion (MxFeyClzn-) with the coordination-unsaturated FeCl3. Upon reduction, the ordered heterobimetallic ions are simultaneously transformed into IMNCs and embedded into gamma-Fe2O3 nanosheets, which form from excess FeCl3. In addition to providing convincing spectral evidence for the structure of the heterobimetallic ions, magnetic measurements, atomic-resolution electron microscopy, X-ray absorption spectroscopy, and Fourier transform infrared spectroscopy of chemisorbed CO collectively confirm the successful preparation of the L1(0)-phased Pd3Fe IMNCs. Furthermore, this versatile method can be extended to synthesize other IMNCs, such as AuFe and PtFe, and seems to be applicable to IrFe, RhFe, RuFe, and MCo. When utilized as a heterogeneous catalyst in a Heck coupling reaction, the prepared Pd3Fe IMNCs display satisfactory activity and stability, highlighting their potential applications as advantageous catalysts.