Gold nanoparticle-decorated halloysite nanotubes – Selective catalysts for benzyl alcohol oxidation

Philip, Anish; Lihavainen, Jenna; Keinänen, Markku; Pakkanen, Tuula T.

doi:10.1016/j.clay.2017.03.015

Cited by 46 publications

(23 citation statements)

References 34 publications

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“…Hal is a 1:1 aluminosilicate mineral with the empirical formula Al 2 Si 2 O 5 (OH) 4 , the typical diffraction peaks of Hal are observed at 2 θ = 12.3, 18.3, 20.2, 24.8°, and the diffraction peaks of quartz are located at 2 θ = 20.8, 26.7, and 36.6° (Figure 4A) (Philip et al, 2017). Figure 4B gives XRD pattern of Mt, its characteristic diffraction peaks are located at 2 θ = 5.9, 19.7, and 35.1°, while the diffraction peaks at 2 θ = 12.5 and 17.5° are attributed to illite (Wang et al, 2016; Liang et al, 2017).…”

Section: Resultsmentioning

confidence: 99%

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation

Zhang

Wang

et al. 2018

Front. Chem.

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Different kinds of aluminosilicate minerals were employed to fabricate CoAl2O4 hybrid pigment for studying its formation and coloring mechanism. It revealed that the color of the obtained hybrid pigments was determined by the content of Al2O3 and lightness of clay minerals. The higher the Al2O3 content and the lightness of clay minerals, the better the color parameters of hybrid pigments. During the preparation of hybrid pigments, CoAl2O4 nanoparticles were confined to be loaded on the surface of the aluminosilicate minerals, which effectively prevented from the aggregation and the size increase of CoAl2O4 nanoparticles. What's more, aluminosilicate mineral might be an ideal natural aluminum source to compensate the aluminum loss due to the dissolution of Al(OH)3 at alkaline medium during precursor preparation, keeping an optimum molar ratio of Co2+/Al3+ for formation of spinel CoAl2O4 pigments in the process of high-temperature crystallization.

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Section: Resultsmentioning

confidence: 99%

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation

Zhang

Wang

et al. 2018

Front. Chem.

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“…In recent years, many studies have been conducted experimentally on the adsorption of gold nanoparticles onto clay minerals such as montmorillonite [5,[13][14][15][16], kaolinite [17], halloysite [18], zeolite [19], and sepiolite [2,5,[20][21][22]. In these studies, it was emphasized that the modification had a great role in the deposition of AuNPs on the clay surface, and that especially the positively charged salts were important in the coating.…”

Section: Introductionmentioning

confidence: 99%

Coating Mechanism of AuNPs onto Sepiolite by Experimental Research and MD Simulation

et al. 2019

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The amenability of gold nanoparticles (AuNPs) coating on natural and modified (hexadecyl trimethyl ammonium bromide, CTAB) sepiolite surfaces was studied both experimentally and theoretically. The zeta potential experiments and Fourier transform infrared spectrophotometer (FTIR), environmental scanning electron microscope (ESEM), and transmission electron microscopy (TEM) analyses were carried out with the sepiolite samples in the presence of AuNPs. In addition, the adsorption of three gold-nanoparticles on the sepiolite surface (100) in the absence and presence of CTAB was investigated by molecular dynamics (MD) simulations. The AuNPs showed no significant change in the zeta potential of natural sepiolite surfaces due to negative charges of both the sepiolite and AuNPs at natural pH. The surface charge of modified sepiolite decreased with the increase in AuNPs concentration indicating the significance AuNPs adsorption. FTIR, ESEM, and TEM analyses indicated the coating of AuNPs onto the modified sepiolite surface were higher than that of the natural sepiolite surface. The MD simulation results showed that AuNPs can easily adsorb onto the basal surface of the sepiolite due to its hydrophilicity in the presence and absence of CTAB as indicated in the experimental studies. In short, the modification of sepiolite with CTAB made the charge positive, and in turn considerably increased the AuNPs coating on sepiolite surfaces due to electrostatic attraction.

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“…To the best of our knowledge, there are very few reports of the immobilization of AuNPs on functionalized halloysite, and all of these consider the formation of metal nanoparticles by calcination methods …”

Section: Introductionmentioning

confidence: 99%

Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications

Massaro

Colletti

Fiore

et al. 2018

Applied Organom Chemis

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A highly sustainable prototype of a flow system based on gold nanoparticles (4.2 nm) supported on thiol‐functionalized halloysite nanotubes (HNTs) was developed for catalytic applications. The catalytic performances were evaluated using the reduction of 4‐nitrophenol to 4‐aminophenol as a model system. Under the best experimental conditions (0.0001 mol%, 1.97 × 10−8 mg of Au nanoparticles), an impressive apparent turnover frequency value up to 2 204 530 h−1 was achieved and the halloysite‐based catalyst showed full recyclability even after ten cycles. The high catalytic activity confirms the importance of the use of HNTs as support for Au nanoparticles that can exert a synergistic effect both as medium for transfer of electrons from borohydride ions to 4‐nitrophenol and by modulating interfacial electron transfer dynamics. With the application of flow technology, the obtained heterogeneous HNT@Au catalyst was fully recovered and reused for at least one month.

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Gold nanoparticle-decorated halloysite nanotubes – Selective catalysts for benzyl alcohol oxidation

Cited by 46 publications

References 34 publications

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation

Formation and Coloring Mechanism of Typical Aluminosilicate Clay Minerals for CoAl2O4 Hybrid Pigment Preparation

Coating Mechanism of AuNPs onto Sepiolite by Experimental Research and MD Simulation

Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications

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