Laves phase Ir2Sm intermetallic nanoparticles as a highly active electrocatalyst for acidic oxygen evolution reaction

Rare earth (RE) intermetallic nanoparticles (NPs) are significant for fundamental explorations and promising for practical applications in electrocatalysis. However, they are difficult to synthesize because of the unusually low reduction potential and extremely high oxygen affinity of RE metal-oxygen bonds. Herein, intermetallic Ir2Sm NPs were firstly synthesized on graphene as a superior acidic oxygen evolution reaction (OER) catalyst. It was verified that intermetallic Ir2Sm is a new phase belonging to the C15 cubic MgCu2 type in the Laves phase family. Meanwhile, intermetallic Ir2Sm NPs achieved a mass activity of 1.24 A mg(Ir)(-1) at 1.53 V and stability of 120 h at 10 mA cm(-2) in 0.5 M H2SO4 electrolyte, which corresponds to a 5.6-fold and 12-fold enhancement relative to Ir NPs. Experimental results together with density functional theory (DFT) calculations show that in the structurally ordered intermetallic Ir2Sm NPs, the alloying of Sm with Ir atoms modulates the electronic nature of Ir, thereby reducing the binding energy of the oxygen-based intermediate, resulting in faster kinetics and enhanced OER activity. This study provides a new perspective for the rational design and practical application of high-performance RE alloy catalysts.