Easily Processable, Highly Transparent and Conducting Thiol-Functionalized Reduced Graphene Oxides Langmuir-Blodgett Films

Equipment-Free Fabrication of Thiolated Reduced Graphene Oxide Langmuir-Blodgett Films: A Novel Approach for Versatile Surface Engineering

This research presents a novel method for the fabrication of mercapto reduced graphene oxide (m-RGO) Langmuir-Blodgett (LB) films without the need for specialized equipment. The conventional LB technique offers precise control over the deposition of thin films onto solid substrates, but its reliance on sophisticated instrumentation limits its accessibility. In this study, we demonstrate a simplified approach that circumvents the necessity for such equipment, thereby democratizing the production of m-RGO LB films. Thiolation of reduced graphene oxide (rGO) imparts enhanced stability and functionality to the resulting films, rendering them suitable for a wide range of applications in surface engineering, sensing, and catalysis. The fabricated m-RGO LB films exhibit favorable morphological, structural, and surface properties, as characterized by various analytical techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Furthermore, the performance of the m-RGO LB films is evaluated in terms of their surface wettability, electrochemical behavior, and chemical reactivity. The equipment-free fabrication approach presented herein offers a cost-effective and scalable route for the production of functionalized graphene-based thin films, thus broadening the scope for their utilization in diverse technological applications.

Facile synthesis of multifunctional C@Fe3O4-MoO3-rGO ternary composite and its versatile roles as sonoadsorbent to ameliorate triphenylmethane textile dye and as potential electrode for supercapacitor applications

The toxic wastewater effluents from textile dyes have been a significant environmental threat worldwide in recent decades. Against this backdrop, this study investigates the performance of C@Fe₃O₄-MoO₃-rGO as a sonoadsorbent to ameliorate crystal violet (CV) dye from the aqua matrix and further explores its potential as an electrode in supercapacitor applications. The phase purity, crystal structure, surface morphology, thermal stability and magnetic behaviour characteristics of the composite were studied using various characterisation techniques such as powder X-ray diffraction (XRD), Raman Spectroscopy, Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), Thermogravimetric analysis (TGA) and Vibrating-sample magnetometry (VSM). From the Langmuir isotherm model, the synthesised sonoadsorbent exhibited a maximum adsorption capacity of 1664.26 mg/g for crystal violet, which is remarkably high. Further, to its inherited magnetic characteristics, the composite can be easily separated from the solution by using an external magnet. Furthermore, the working electrode was synthesised with 80% active material, 10% carbon black, and 10% polyvinylidene difluoride to investigate its suitability in supercapacitor applications. The C@Fe₃O₄-MoO₃-rGO composite exhibited an excellent capacitance value of 180.36 F/g with commendable cycling stability, making it suitable as a potential cathode material for the next generation supercapacitors.

Thiol-Functionalization Carbonaceous Adsorbents for the Removal of Methyl-Mercury from Water in the ppb Levels

Mercury is a highly toxic pollutant of major public health concern, and human exposure is mainly related to the aqueous phase, where its dominant form is methyl-mercury (MeHg). In the current work, two carbon-based adsorbents, i.e., a commercial activated carbon and a sunflower seeds’ biochar, were modified by the introduction of thiol-active groups onto their surfaces for the MeHg removal from natural-like water in ppb concentration levels. The examined thiol-functionalization was a two-step process, since the raw materials were initially treated with nitric acid (6 N), which is a reagent that favors the formation of surface carboxyl groups, and subsequently by the thiol surface bonding groups through an esterification reaction in methanol matrix. The adsorbents’ capacity was evaluated toward the Hgtotal legislative regulation limit (1 μg/L) in drinking water (denoted as Q1). The respective isothermal adsorption results revealed an increased affinity between MeHg and thiol-functionalized materials, where the commercial carbon showed slightly higher capacity (0.116 μg Hg/mg) compared with the biochar (0.108 μg Hg/mg). This variation can be attributed to the respective higher surface area, resulting, also, to higher thiol groups loading. Regarding the proposed mechanism, it was proved that the S-Hg bond was formed, based on the characterization of the best performed saturated adsorbent.