Solving the Limitation in the Slow Synthesis Method to Minimize Reaction Time Differences for Synthesizing Au<sub><i>x</i></sub>Os<sub>1-<i>x</i></sub> Solid-Solution NO<sub><i>x</i></sub> Reduction Catalysts.

Gao, Junyun; Zheng, Jie; Huang, Bo · Nano Lett · 2026

basic_science · Level V

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Abstract

The syntheses of solid-solution alloys consisting of elements with large redox-potential differences remain significant challenges. In this work, by a slow synthesis method, we precisely controlled the reduction, nucleation, and growth processes of Au and Os and successfully synthesized homogeneous Au<sub><i>x</i></sub>Os<sub>1-<i>x</i></sub> solid-solution NPs for the first time, which cannot mix with each other over most composition ranges up to 3000 °C. The reaction-area confinement effect in the spray method was proved to be favorable for preventing Au phase segregation. In NO<sub><i>x</i></sub> reduction tests, Au<sub>0.1</sub>Os<sub>0.9</sub> NPs showed much higher activity with a temperature at 50% conversion (<i>T</i><sub>50</sub>) of 239 °C than the state-of-the-art monometallic Rh catalysts (<i>T</i><sub>50</sub> of 267 °C). Based on <i>in situ</i> Fourier transform infrared measurements and density functional theory calculations, the modifications of Os electronic states via Au alloying significantly enhanced CO and NO activation at Os sites, leading to the excellent NO<sub><i>x</i></sub> reduction catalytic activities for Au<sub><i>x</i></sub>Os<sub>1-<i>x</i></sub> solid-solution NPs.