Aerobic Oxidation of Alcohols over Isolated Single Au Atoms Supported on CeO₂ Nanorods: Catalysis of Interfacial [O–Ov–Ce–O–Au] Sites

Abstract

The oxidation of alcohols is a kind of very important reaction in industry and has caused great concern in recent years, especially with molecular oxygen as the oxidant. Among various catalysts reported in the literature, Au/CeO2 exhibits excellent catalytic performance in the oxidation of alcohols, with aldehydes as the target product. However, there is still not a clear consensus regarding the nature of the active sites of Au/CeO2 related catalysts. In this contribution, three distinctly different Au species supported on CeO2 nanorods (CeO2-NR) were prepared (viz., isolated single Au atoms (Au-SA), Au nanoclusters (Au-NC), and Au nanoparticles (Au-NP)); their catalytic performances in the aerobic oxidation of alcohols was comparatively investigated in order to discriminate the active sites in Au/CeO2. A series of characterization results combining with DFT calculation illustrates that the performance of Au/CeO2 catalysts in alcohol oxidation is closely related to the size of Au species and the concentration of oxygen vacancies (Ov), where the interfacial [O–Ov–Ce–O–Au] sites between Au species and CeO2 support play an important role in catalyzing the alcohol oxidation. The oxygen vacancies in CeO2 facilitate the adsorption of alcohol and the dissociation of the O–H bond, whereas the adjacent Au3+/Au+ species can promote the elimination of β-hydride in the alkoxide intermediate. As the Au-SA/CeO2-NR catalyst is provided with abundant active [O–Ov–Ce–O–Au] sites, it exhibits much higher activity in the oxidation of alcohols, in comparison with Au-NC/CeO2-NR and Au-NP/CeO2-NR. The insight shown in this work should be helpful in understanding the catalysis of interfacial sites between metal and an oxide support and developing better catalysts for the oxidation of alcohols.

Microenvironment Engineering of Ru Single‐Atom Catalysts by Regulating the Cation Vacancies in NiFe‐Layered Double Hydroxides

“…The oxidation process of benzyl alcohol was proposed to include the following steps. [ 23 ] Step 1: I→II, the benzyl alcohol molecule (C 7 H 8 O) spontaneously adsorbed on the Ru single atom site with O atom bonded to the Ru atom, and H atom of the alcohol group bonded to the neighboring lattice O atom in LDH support. Step 2: II→III, the O–H bond of benzyl alcohol was then eliminated to form C 7 H 7 O* and H 2 O*.…”

Oxidation of Sodium Deoxycholate Catalyzed by Gold Nanoparticles and Chiral Recognition Performances of Bile Salt Micelles

“…It indicates that the generated Au NPs acted as catalysts for the oxidation of NaDC. Noble metal NPs are widely used as catalysts for oxidation reactions (such as alcohol and CO oxidations) and hydrogenation reactions [33,34]. The reaction temperature has an important influence on the reaction rate.…”

Bimetallic PdAu Catalysts within Hierarchically Porous Architectures for Aerobic Oxidation of Benzyl Alcohol

“…Many research reports have investigated that the textural and chemical properties of support materials, type of metal and size of NPs directly influence the catalytic activity and selectivity of oxidation reaction ( Table S1 ) [ 11 , 12 , 13 , 14 , 15 , 16 ]. The Au NPs supported on metal oxides (TiO 2 , CeO 2 , Al 2 O 3 , MgO) and carbon materials [ 17 , 18 , 19 ] have been reported to be the active catalysts for alcohol oxidation reactions [ 7 , 20 , 21 , 22 ]. Many research groups have explored the use of Au [ 23 ], Pd [ 24 , 25 ] and PdAu [ 26 ] bimetallic NPs on these support materials [ 20 , 21 , 22 , 23 , 27 , 28 ].…”

“…The Au NPs supported on metal oxides (TiO 2 , CeO 2 , Al 2 O 3 , MgO) and carbon materials [ 17 , 18 , 19 ] have been reported to be the active catalysts for alcohol oxidation reactions [ 7 , 20 , 21 , 22 ]. Many research groups have explored the use of Au [ 23 ], Pd [ 24 , 25 ] and PdAu [ 26 ] bimetallic NPs on these support materials [ 20 , 21 , 22 , 23 , 27 , 28 ]. The oxide supported bimetallic catalysts, in particular the combination of Pd and Au, has been recognised for its highly active and selective oxidation abilities in various important catalytic transformations by weakly adsorbing the reactants and products on its surface to form target molecules [ 24 , 25 , 26 , 29 , 30 , 31 ].…”