Electrosynthesis of NH3 through the N2 reduction reaction (NRR) under ambient conditions is regarded as promising technology to replace the industrial energy‐ and capital‐intensive Haber–Bosch process. Herein, a room‐temperature spontaneous redox approach to fabricate a core–shell‐structured Au@CeO2 composite, with Au nanoparticle sizes below about 10 nm and a loading amount of 3.6 wt %, is reported for the NRR. The results demonstrate that as‐synthesized Au@CeO2 possesses a surface area of 40.7 m2 g−1 and a porous structure. As an electrocatalyst, it exhibits high NRR activity, with an NH3 yield rate of 28.2 μg h−1 cm−2 (10.6 μg h−1 mg−1cat., 293.8 μg h−1 mg−1Au) and a faradaic efficiency of 9.50 % at −0.4 V versus a reversible hydrogen electrode in 0.01 m H2SO4 electrolyte. The characterization results reveal the presence of rich oxygen vacancies in the CeO2 nanoparticle shell of Au@CeO2; these are favorable for N2 adsorption and activation for the NRR. This has been further verified by theoretical calculations. The abundant oxygen vacancies in the CeO2 nanoparticle shell, combined with the Au nanoparticle core of Au@CeO2, are electrocatalytically active sites for the NRR, and thus, synergistically enhance the conversion of N2 into NH3.
We present the self-assembly synthesis of core-shell structure Au/CeO composites with different Au loadings through a spontaneous chemical redox approach at an ambient temperature utilizing HAuCl and Ce(NO) as reaction substrates in an alkaline environment. The results demonstrate that the as-synthesized Au/CeO composites exhibit spherical shape morphologies with porous structures, composed of Au nanoparticle (∼10 nm) cores and CeO nanoparticle shells with abundant oxygen vacancies. The introduction of Au nanoparticles in CeO 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/CeO 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/CeO 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 CeO synergistically contribute to the high performance of the selective photocatalytic oxidation of alcohols to aldehydes or ketones.
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