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.

Fe-based catalysts have been discovered as the best elementary metal-based heterogeneous catalysts for the ammonia synthesis in industrial application during the last century. Herein, a novel and scalable strategy is developed to prepare the K-promoted Fe/C catalyst with extremely high Fe loading (> 50 wt.%) through pyrolysis of the Fe-based metal-organic framework (MOF) xerogel. The obtained K-Fe/C catalysts exhibited superior activity and stability towards ammonia synthesis. The weight-specific reaction rate of Fe/C with K₂O as promoter can achieve 12.4 mmol·g^-1·h^-1 at 350 ℃ and 30.4 mmol·g^-1·h^-1 at 400 ℃, approximately four and two times higher than that of the commercial fused-iron catalyst (3.4 mmol·g^-1·h^-1 at 350 ℃ and 16.7 mmol·g^-1·h^-1 at 400 ℃) under the same condition, respectively. The excellent performance of K-Fe/C can be ascribed to the inherited structure derived from the metal-organic frame precursors and the promotion of potassium, which can modify the binding energy of reactant molecules on the Fe surface, transfer electrons to iron for effective activation of nitrogen, prevent agglomeration of Fe nanoparticle (NPs) and restrain side reaction of carbon matrix to methane.