Striking effects are expected in solid-solution alloying, which offers enormous possibilities for various applications, especially in industrial catalysis. However, phase diagrams have revealed that a wide range of metallic elements are immiscible with each other even above their melting points. Achieving such unknown alloying between different immiscible metallic elements is highly desirable but challenging. Here, for the first time, by using an innovative solid ligand-assisted approach, we achieve the solid-solution alloying between the bulk-immiscible Au and Rh in plenty of clean, ultrafine (~ 1.6 nm) and highly dispersed nanoclusters. The solid-solution alloying of immiscible Au and Rh significantly enhances their catalytic performance toward the hydrogen evolution from formic acid in contrast to the monometallic Au and Rh nanoclusters. Moreover, the resultant binary solid-solution nanoclusters are stable without any segregation during catalytic reactions. The approach demonstrated here for homogeneously mixing the immiscible metals at the atomic scale will benefit the creation of advanced alloys and their catalytic applications in future.

Carbon nanospheres (XC-72R) were functionalized by boron-oxygen (B-O) through coannealing with boric acid, to which highly dispersed palladium nanoparticles (Pd NPs) (~ 1.7 nm) were immobilized by a wet chemical reduction for the first time. The resultant Pd/OB-C catalyst exhibits significantly improved activity for the dehydrogenation from formic acid (FA) compared to pristine XC-72R supported Pd NPs (Pd/C). Impressively, by adding melamine precursor, the B-O and nitrogen (N)-functionalized product OB-C-N displays an extremely high B content, ca. 34 times higher than OB-C. The Pd/OB-C-N catalyst with an ultrafine Pd particle size of ~ 1.4 nm shows a superb activity, with a turnover frequency (TOF) as high as 5, 354 h^-1 at 323 K, owing to the uniform ultrafine Pd NPs and the effect from B-O and N functionalities.

Downsizing noble metal nanoparticles, such as Pt, is an essential goal for many catalytic reactions. A non-noble metal sacrificial approach was used to immobilize monodispersed Pt nanoparticles (NPs) with a mean size of 1.2 nm on reduced graphene oxide (RGO). ZnO co-precipitated with Pt NPs and subsequently sacrificed by acid etching impedes the diffusion of Pt atoms onto the primary Pt particles and also their aggregation during the reduction of precursors. The resulting ultrafine Pt nanoparticles exhibit high activity (a turnover frequency of 284 min^-1 at 298 K) in the hydrolytic dehydrogenation of ammonia borane. The non-noble metal sacrificial approach is demonstrated as a general approach to synthesize well-dispersed noble metal NPs for catalysis.

Magnetically recyclable Au/Co/Fe core–shell nanoparticles (NPs) have been successfully synthesized via a one-step in situ procedure. Transmission electron microscope (TEM), energy dispersive X-ray spectroscopic (EDS), and electron energy-loss spectroscopic (EELS) measurements revealed that the trimetallic Au/Co/Fe NPs have a triple-layered core–shell structure composed of a Au core, a Co-rich inter-layer, and a Fe-rich shell. The Au/Co/Fe core–shell NPs exhibit much higher catalytic activities for hydrolytic dehydrogenation of ammonia borane (NH₃BH₃, AB) than the monometallic (Au, Co, Fe) or bimetallic (AuCo, AuFe, CoFe) counterparts.