Transparent and Hydrophobic “Reduced Graphene Oxide–Titanium Dioxide” Nanocomposites for Nonwetting Device Applications

Abstract

Graphene oxide−titanium dioxide (GO−TiO 2 ) nanocomposite sheets were transferred onto Si and quartz substrates by Langmuir−Blodgett (LB) technique at different subphase TiO 2 concentrations and pH values. The effects of subphase and heat treatment conditions on the composition, surface morphology, microstructure, and hydrophobic performance of the composite sheets were investigated by XPS, Raman, AFM, HR-TEM, and contact-angle measurements. The wetting behavior of composite sheets before and after vacuum heat treatment was analyzed in conjunction with the extent of TiO 2 uptake, distribution of nanoparticles over GO sheets, and overall surface roughness. The degree of subphase ionization significantly affects the uptake and aggregation behavior of TiO 2 , which tends to be dominated by the interaction of TiO 2 with carboxylic acid functional groups at the edges of the GO sheets. Wettability studies revealed improvement in the hydrophobicity of composite sheets compared to the GO sheets, which is attributed primarily to the larger surface roughness induced by TiO 2 nanoparticles. Heat treatment in vacuum causes formation of a reduced graphene oxide (rGO) wrap on the surface of TiO 2 nanoparticles, which substantially enhances the hydrophobicity of the composite sheets. UV exposure causes deterioration of the hydrophobicity of as-transferred composite sheets, while the heat-treated composites retain their superior hydrophobicity, owing to the presence of a rGO wrap, which hinders the reconstruction of surface −OH groups on TiO 2 . The rGO−TiO 2 composite sheets exhibit high transmittance in the visible region and undeteriorated hydrophobic behavior even after prolonged UV irradiation, which have potential applications in the development of flexible transparent nonwetting electronic devices.

Titanium Dioxide Nanoparticles Modified with Disulfonic Acid Functionalized Imidazolium Ionic Liquids for Use as Electrorheological Materials

“…In the C 1s spectrum (Figure b), the peaks at 284.6 and 285.6 eV correspond to the chemical bands of C–C and C–O. The binding energy of 288.6 eV represents the Ti–O–C, , suggesting incomplete hydrolysis of TBT with some alkoxy chains remaining in the TiO 2 -based nanoparticles. Figure a,b exhibits that the peak positions of Ti 2p and C 1s are unmoved after the addition of [Dsim]­Cl.…”

TiO2 Nanoparticles Dual-Modified with Ionic Liquid and Acetic Acid for Use as Electrorheological Materials to Achieve Ultrahigh and Stable Electroresponsive Performances

“…There are two main peaks at 464.2 and 458.5 eV in the spectra, which are attributed to the binding energies of Ti 2p 1/2 and 2p 3/2 , respectively. The XPS peak of C 1s can be deconvoluted into three peaks (Figure b), among which 284.6 and 286.01 eV correspond to the binding energies of C–C and C–O, respectively, and that at 288.5 eV can be attributed to Ti–O–C . The chemical bond of Ti–O–C may have two sources: the incomplete hydrolysis of the alkyl chain in TBT and the other is the new chemical bond formed by the AA and Ti.…”

Batch and continuous studies on adsorptive removal of hexavalent chromium [Cr(VI)] using reduced graphene oxide

“…Also, the hydrophilic nature of GO changes to hydrophobic after reduction, which is necessary for adsorption operation. [23] In RGO, the presence of sp 2 hybridized carbon atoms, lots of defects, π-electron domains, and wrinkles significantly affect the adsorption of Cr(VI). [24] Nevertheless, quite a few pieces of literature are available to remove heavy metal ion using graphene-based adsorbents.…”