The exceptional physico‐chemical properties of ionic liquids are exploited for the synthesis and catalytic application of heterometallic nanoparticles. Pt/Sn‐based nanoparticles with 2–3 nm diameter are synthesized by chemical reduction of the metal salt precursors in the ionic liquid (i.e., methyltrioctylammonium bis(trifluoromethylsulfonyl)imide) using triethylborohydride as reducing agent. Investigations by X‐ray diffraction, X‐ray photoelectron spectroscopy and transmission electron microscopy suggest the formation of randomly alloyed Pt/Sn‐based nanoparticles. The tin precursor and the platinum to tin ratio of the precursors are shown to influence the nature of the nanoparticles. The selective hydrogenation of cinnamaldehyde is used to probe the catalytic performance of the Pt/Sn nanoparticles, demonstrating the effect of tin alloying on the catalytic activity and selectivity to the α,β‐unsaturated cinnamic alcohol.

Multimetallic nanoparticles often enhance the catalytic performance of their monometallic counterparts by increasing reaction rates, catalyst selectivity, and/or stability. A prerequisite for understanding structure‐ and composition‐associated properties, however, is the careful design of multimetallic nanoparticles with various structures and compositions. Here, bimetallic Pd/Sn‐based nanoparticles are prepared with a tunable composition and structure exploiting ionic liquids (ILs) as reaction medium (i. e., methyltrioctylammonium bis(trifluoromethylsulfonyl)imide). The nanoparticles are obtained in a one‐pot synthetic procedure by reducing the metal salt precursors with triethylborohydride in the IL. The results show that the reaction parameters, in particular the nature and ratio of the Pd 2+ /Sn 2+ precursors as well as the reaction temperature, influence NP formation and composition. X‐ray diffraction with Rietveld analysis and transmission electron microscopy are employed to determine NP size and phase composition. Under optimized reaction conditions Pd 2 Sn or PdSn nanocrystals are formed as single‐phase products after introducing an additional annealing step at 200 °C. Nanocrystals with intermetallic composition reveal enhanced catalytic properties in the semihydrogenation of diphenylacetylene which was used as a model reaction.

Bimetallic NiIr4 and NiOs4 alloy nanoparticles are prepared and studied with regard to their performance in catalytic hydrogenation reactions. NiIr4 and NiOs4 nanoparticles are obtained by oleylamine‐driven reduction and exhibit mean diameters of (8.9±1.3) and (6.8±1.4) nm at low agglomeration. The phase composition was determined in detail by using different methods, which include high‐resolution TEM, scanning transmission electron microscopy, selected‐area electron diffraction, X‐ray diffraction, and energy‐dispersive X‐ray spectroscopy. This and results in a uniform distribution of both metals Ni‐Ir and Ni‐Os with a ratio of 1:4. The catalytic performance of the NiIr4 and NiOs4 nanoparticles for hydrogenation reactions is evaluated using three selected model substrates: 1‐octene, cinnamaldehyde, and diphenylacetylene. Similar sized Ni, Ir, and Os nanoparticles were used as references. Most remarkable are the excellent selectivity of NiOs4 in the hydrogenation of cinnamaldehyde and the promising formation of (Z)‐stilbene in terms of conversion activity and selectivity. The alloying of Ir and Os with Ni, moreover, is highly cost efficient. In general, both bimetallic alloy nanoparticles, NiIr4 and NiOs4, are shown here for the first time in terms of synthesis, composition, and catalytic hydrogenation.

Multimetallic nanoparticles (NPs) often exhibit enhanced catalytic properties that differ from their parent materials. Carefully exploring the structures of multimetallic NPs is a prerequisite for understanding the structure-and composition-associated properties. Herein, intermetallic Pt/Sn NPs with tunable compositions are designed exploiting the beneficial properties of ionic liquids (ILs) in a one-pot synthetic procedure. Metal salt precursors are reduced with triethylhydridoborate, whereby the cation of the triethylhydridoborate is adapted to the cation of the IL. Both the initial metal precursor ratio and the type of IL influence the structure of the NPs, with the effect of the IL being more pronounced. PtSn nanocrystals are obtained as phase pure products under optimized reaction conditions, whereby a microwave-assisted approach leads to higher crystallinity. In the hydrogenation of α,β-unsaturated aldehydes, the catalytic performance obviously depend on the NP composition. In bimetallic Pt/Sn NPs, higher Pt content leads to increased conversion, while increase in Sn increases selectivity to the cinnamic alcohol.