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

Abstract

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.

Structuring Pickering Emulsion Interfaces with Bilayered Coacervates of Cellulose Nanofibers and Hectorite Nanoplatelets

“…Thereafter, we confirmed that the treatment with a cationic surfactant, 2M2HT, provided the surface of AHNPs with positive charges (∼10 mV) (Figure 2c). 28,29 Successful surface modification of the AHNPs with 2M2HT was also confirmed from the X-ray diffraction (XRD) pattern, indicating that the basal spacing (d 001 ) of the AHNPs increased from 1.29 to 2.39 nm because of the intercalation of 2M2HT between hectorite layers. (Figure 3d).…”

Zr supported on non-acidic sepiolite for the efficient one-pot transformation of furfural into γ-valerolactone

“…These bands are associated at water disappearance when the sample is calcined, therefore these bands cannot be observed in the rest of the catalysts and in the calcined sepiolite. Peaks from 1000 cm − to 900 cm − 1 corresponds to silicates (Si-O-Si), peaks from 750 cm − 1 to 600 cm − 1 correspond to magnesium hydroxides and finally, peaks at 450 cm − 1 are related to Si-O-Mg of the octahedral-tetrahedral linkage [54][55][56]. The spectra of pure ZrO 2 present a peak at 750 cm − 1 , which is attributed to Zr-O stretching vibrations at ZrO 2 [57].…”