Spontaneous Redox Approach to the Self-Assembly Synthesis of Au/CeO₂ Plasmonic Photocatalysts with Rich Oxygen Vacancies for Selective Photocatalytic Conversion of Alcohols

Abstract

We present the self-assembly synthesis of core-shell structure Au/CeO₂ composites with different Au loadings through a spontaneous chemical redox approach at an ambient temperature utilizing HAuCl₄ and Ce(NO₃)₃ as reaction substrates in an alkaline environment. The results demonstrate that the as-synthesized Au/CeO₂ composites exhibit spherical shape morphologies with porous structures, composed of Au nanoparticle (∼10 nm) cores and CeO₂ nanoparticle shells with abundant oxygen vacancies. The introduction of Au nanoparticles in CeO₂ not only effectively improves the visible light utilization efficiency but also provides rich surface catalytic active sites for highly efficient visible light photocatalysis. As visible light photocatalysts (λ > 400 nm), the as-synthesized Au/CeO₂ composites with the Au loading amount ≥4.0 wt % exhibit high conversion and selectivity (∼100%) of benzyl alcohol to benzaldehyde under the given experimental conditions. Moreover, Au/CeO₂ also shows a general applicability as a visible light photocatalyst for the selective oxidation of other alcohols to corresponding aldehydes or ketones. The photocatalytic mechanism studies indicate that the photoelectrons/holes produced from the photoexcited Au and the formed superoxide radicals in the oxygen vacancies of CeO₂ synergistically contribute to the high performance of the selective photocatalytic oxidation of alcohols to aldehydes or ketones.