Three-Dimensional Noble-Metal Nanostructures Approaching Atomic Efficiency and Atomic Density Limits.

Noble metals have been widely used in catalysis due to their unique physicochemical properties. For practical application, the scarcity and high cost of noble metal motivate researchers to balance the atomic efficiency and atomic density, which is however formidably challenging. Here, we propose a robust strategy for fabricating three-dimensional (3D) amorphous noble metal-based oxides with simultaneous enhancement on atomic efficiency and density with the assistance of atomic channels, where the atomic utilization increased from 18.2% to 59.4% after the creation of atomic channels. The unique properties of amorphous bimetallic oxides and formation of atomic channels have been evidenced by atomic-resolution microstructural characterization, in situ and ex situ X-ray absorption spectroscopy, synchrotron radiation induced photoemission spectroscopy, Ar + -etching X-ray photoelectron spectroscopy, and theoretical simulations. Moreover, the universality of the current strategy is validated by creating atomic channels in amorphous Ir- and Pt-based binary oxides. When amorphous Cu 2 IrO x with atomic channels (Cu 2 IrO x -AE) was used as catalyst for oxygen evolution reaction (OER), the mass activity and turnover frequency value of Cu 2 IrO x -AE are 1-2 orders of magnitude higher than those of crystalline CuO/IrO 2 and amorphous Cu 2 IrO x without atomic channels, largely outperforming the reported OER catalysts. Theoretical calculations reveal that the formation of atomic channels lead to various Ir sites, on which the proton of adsorbed * OH can transfer to adjacent O atoms of [IrO 6 ], as a result of significant decrease of energy barrier for the rate-determining step for OER. This work provides a promising strategy for simultaneously increasing exposed surface atoms and atomic efficiency of noble metals, which may attract immediate interests of researchers in material science, chemistry, catalysis and beyond. This article is protected by copyright. All rights reserved.