Phase textures of metal–oxide nanocomposites self-orchestrated by atomic diffusions through precursor alloys

Abstract

Metal-oxide nanocomposites (MONs) are of pivotal importance as electrode materials, yet lack a guiding principle to tune their phase texture. Here we report that the phase texture of MONs can be tuned at the nanoscale by controlling the nanophase separation of precursor alloys. In situ transmission electron microscopy (in situ TEM) has demonstrated that a MON material of platinum (Pt) and cerium oxide (CeO₂) is obtained through promoted nanophase separation of a Pt₅Ce precursor alloy in an atmosphere containing oxygen (O₂) and carbon monoxide (CO). The Pt–CeO₂ MON material comprised an alternating stack of nanometre-thick layers of Pt and CeO₂ in different phase textures ranging from lamellae to mazes, depending on the O₂ fraction in the atmosphere. Mathematical simulations have demonstrated that the phase texture of MONs originates from a balance in the atomic diffusions across the alloy precursor, which is controllable by the O₂ fraction, temperature, and composition of the precursor alloys.