Amplified Interfacial Effect in an Atomically Dispersed RuOx -on-Pd 2D Inverse Nanocatalyst for High-Performance Oxygen Reduction.

Atomically dispersed oxide-on-metal inverse nanocatalysts provide a blueprint to amplify the strong oxide-metal interactions for heterocatalysis but remain a grand challenge in fabrication. Here we report a 2D inverse nanocatalyst, RuOx -on-Pd nanosheets, by in situ creating atomically dispersed RuOx /Pd interfaces densely on ultrathin Pd nanosheets via a one-pot synthesis. The product displays unexpected performance toward the oxygen reduction reaction (ORR) in alkaline medium, which represents 8.0- and 22.4-fold enhancement in mass activity compared to the state-of-the-art Pt/C and Pd/C catalysts, respectively, showcasing an excellent Pt-alternative cathode electrocatalyst for fuel cells and metal-air batteries. Density functional theory calculations validate that the RuOx /Pd interface can accumulate partial charge from the 2D Pd host and subtly change the adsorption configuration of O2 to facilitate the O-O bond cleavage. Meanwhile, the d-band center of Pd nanosubstrates is effectively downshifted, realizing weakened oxygen binding strength.