High-degree functionalization of graphene oxide (GO) nanoparticles (NPs) using polydopamine (PDA) was conducted to produce polydopamine functionalized graphene oxide nanoparticles (GO-PDA NPs). Aiming to explore their potential use as nanofiller in membrane separation processes, the spectral and structural properties of GO-PDA NPs were comprehensively analyzed. GO NPs were first prepared by the oxidation of graphite via a modified Hummers method. The obtained GO NPs were then functionalized with PDA using a GO:PDA ratio of 1:2 to obtain highly aminated GO NPs. The structural change was evaluated using XRD, FTIR-UATR, Raman spectroscopy, SEM and TEM. Several bands have emerged in the FTIR spectra of GO-PDA attributed to the amine groups of PDA confirming the high functionalization degree of GO NPs. Raman spectra and XRD patterns showed different crystalline structures and defects and higher interlayer spacing of GO-PDA. The change in elemental compositions was confirmed by XPS and CHNSO elemental analysis and showed an emerging N 1s core-level in the GO-PDA survey spectra corresponding to the amine groups of PDA. GO-PDA NPs showed better dispersibility in polar and nonpolar solvents expanding their potential utilization for different purposes. Furthermore, GO and GO-PDA-coated membranes were prepared via pressure-assisted self-assembly technique (PAS) using low concentrations of NPs (1 wt. %). Contact angle measurements showed excellent hydrophilic properties of GO-PDA with an average contact angle of (27.8°).

Polydopamine Functionalized Graphene Oxide as Membrane Nanofiller: Spectral and Structural Studies.

Graphene oxide nanocomposites based room temperature gas sensors: A review

Formaldehyde (CH2O) properties such as flash point and autoignition temperature have a great effect on the temperature range of sensitivity of sensors applied to detect CH2O gas. Tin dioxide nanocrystal interaction with formaldehyde is investigated from room temperature to 500 °C using transition state and density functional theory. Gibbs free energy, enthalpy, and entropy of activation and reaction are evaluated as a function of temperature. The sensitivity and response time of SnO2 clusters towards formaldehyde are evaluated. Results show that the activation energy of SnO2 clusters with formaldehyde increases with the rise of temperature while the reaction energy decreases (in negative value) with the rise of temperature. Response time is inversely proportional to formaldehyde concentration. The highest CH2O gas-sensitive range of SnO2 is confined between the formaldehyde flash point at 64 °C and the autoignition temperature at 430 °C. The effect of partial oxidation and dissociation of formaldehyde is discussed.

Effect of formaldehyde properties on SnO2 clusters gas sensitivity: A DFT study.

Two-dimensional nanomaterials (2D nanomaterials) are a sophisticated advanced class of atomically thick nanomaterials that consist of a single to few layers of atoms. The lateral size of the 2D nanomaterials can reach up to micrometers, and even longer can be produced by improving synthesis methods. The 2D nanomaterials have unique features of high anisotropy, effective surface area, mechanical strength, plasmonic, electron confinement, and optical properties. According to the class, the 2D nanomaterials can be tuned to superconductors, semiconductors to insulators. 2D nanomaterials are extensively explored for membranes, energy production/storage, tissue engineering, sensing, and catalytic applications. In this review, we concisely discussed the synthesis, key characteristics, and striking properties of 2D nanomaterials. Finally, review concludes with a future perspective and conclusive remarks. Indeed, ultrathin 2D nanomaterials have become critical players in every field of material science. In the near future, these materials will be revolutionary in the energy and environmental sectors. 

Two-dimensional nanomaterials: A critical review of recent progress, properties, applications, and future directions

Effects of Field-Effect and Schottky Heterostructure on p-Type Graphene-Based Gas Sensor Modified by n-Type In2O3 and Phenylenediamine

A comprehensive study of various amine-functionalized graphene oxides for room temperature formaldehyde gas detection: Experimental and theoretical approaches

Ha Eun Jeong

Papers

A comprehensive study of various amine-functionalized graphene oxides for room temperature formaldehyde gas detection: Experimental and theoretical approaches

Effects of Field-Effect and Schottky Heterostructure on p-Type Graphene-Based Gas Sensor Modified by n-Type In2O3 and Phenylenediamine