General Solvothermal Synthesis Method for Complete Solubility Range Bimetallic and High-Entropy Alloy Nanocatalysts

Nanoalloys (NAs) have extraordinary catalytic properties, but metals are often immiscible giving compositional limits on catalytic design. It is generally believed that solution-based chemical synthesis is inadequate for obtaining NAs, and often exotic shock synthesis or severe decomposition or reduction reactions are required. However, such methods only work on the laboratory scale making real-world applications difficult. Here, a general solvothermal method is reported to obtain phase-pure bimetallic and high-entropy nano-alloys across the entire composition range. Tuning of solvent chemistry and precursors leads to six different bimetallic NAs: PdxRu1-x, PtxRu1-x, IrxRu1-x, RhxRu1-x, Ir1-xPtx, and Rh1-xPtx, without immiscibility regions. All samples have face-centered-cubic crystal structures, which have not previously been observed for the ruthenium-based systems. Additionally, quaternary and quinary systems are produced, demonstrating the ability to obtain medium- and high-entropy NAs. The method described herein provides a simple, general production method of previously unknown solid solutions throughout their entire composition range potentially allowing for detailed tuning of nanocatalyst properties.