By carefully controlling the structure and composition of bimetallic nanoparticles, researchers have come up with a high-performance model catalyst that blends the best features of each metal. The advance could lead to commercial catalysts that cut manufacturing costs and reduce waste. Heterogeneous catalysts, which generally contain one type of metal, drive most industrial-scale chemical processes. Blending two metalscan increase catalysts’ capabilities, for example, by mediating separate steps of a reaction. But most methods for preparing mixed-metal catalysts lead to particles with variations in composition, size, and shape. The lack of control often causes a trade-off between catalytic activity and chemical selectivity. A team of researchers led by Jessi E. S. van der Hoeven, Alfons van Blaaderen, and Petra E. de Jongh of Utrecht University has now shown how to combine metals to make catalysts that are active and selective. The team made a series of uniform nanorods, each with a gold core and a palladium shell of predetermined thickness. The researchers capped the rods with porous silica and tested them catalytically in the selective hydrogenation of 1,3-butadiene, a process used for purifying propene feedstocks. The core-shell catalysts were all highly selective, a trademark of gold, yet they were up to 50 times as active as catalysts made of a single metal or random mixtures of the metals (Nat. Mater. 2021, DOI: 10.1038/s41563-021-00996-3).