Reduced Graphene Oxide Sheets Research Articles

Synthesis and Characterization of Palladium/Silver Modified Reduced Graphene Oxide–Nanocomposite Platform for Electrochemical Sensors

AbstractMetal nanoparticles incorporated into carbon nanostructures have tremendous applications in the field of nanosensors and other technologies. Herein, a nanohybrid of reduced graphene oxide modified with silver and/or palladium nanoparticles (Ag/Pd/rGO) was prepared by impregnation of Pd and Ag into the rGO platform and deposited on a glass carbon electrode. Palladium and silver nanoparticles improve the stability and durability of the sensor platform by preventing the agglomeration of graphene oxide sheets and providing chemical stability against environmental factors. This ensures long‐term reliability and repeatability of the sensor performance. The morphologies and microstructures of the as‐prepared nanohybrid were characterized by X‐ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, UV–visible and infrared spectroscopy. The average crystallite size of PdAgNPs was found to be between 12 and 15 nm and demonstrated good dispersion across reduced graphene oxide sheets with high‐loading capacities. Thorough investigation of the electrochemical properties of the nanomaterial surfaces through cyclic voltammetry (CV) experiments, revealed distinct redox peaks for Ag+/Ag0 and Pd2+/Pd0 processes and demonstrated the excellent electrochemical properties of the prepared nanocomposites. The rGO‐PdAgNPs‐GCE had a diffusion coefficient value of 1.14×10−14 cm2 s−1 which is acceptable for electrochemical sensors as it is indicative of a fast response time and enhanced sensitivity to changes in gas concentration. The results obtained through thorough characterizations contributes to the novelty of the research by offering a deeper understanding of the material properties and the potential of the nanohybrid material for a broad application scope.

Aluminium, Nitrogen-Dual-Doped Reduced Graphene Oxide Co-Existing with Cobalt-Encapsulated Graphitic Carbon Nanotube as an Activity Modulated Electrocatalyst for Oxygen Electrocatalyst for Oxygen Electrochemistry Applications.

There is a rising need to create high-performing, affordable electrocatalysts in the new field of oxygen electrochemistry. Here, a cost-effective, activity-modulated electrocatalyst with the capacity to trigger both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in an alkaline environment is presented. The catalyst (Al, Co/N-rGCNT) is made up of aluminium, nitrogen-dual-doped reduced graphene oxide sheets co-existing with cobalt-encapsulated carbon nanotube units. Based on X-ray Absorption Spectroscopy (XAS) studies, it is established that the superior reaction kinetics in Al, Co/N-rGCNT over their bulk counterparts can be attributed to their electronic regulation. The Al, Co/N-rGCNT performs as a versatile bifunctional electrocatalyst for zinc-air battery (ZAB), delivering an open circuit potential ≈1.35V and peak power density of 106.3mWcm-2, which are comparable to the system based on Pt/C. The Al, Co/N-rGCNT-based system showed a specific capacity of 737mAhgZn -1 compared to 696mAhgZn -1 delivered by the system based on Pt/C. The DFT calculations indicate that the adsorption of Co in the presence of Al doping in NGr improves the electronic properties favoring ORR. Thus, the Al, Co/N-rGCNT-based rechargeable ZAB (RZAB) emerges as a highly viable and affordable option for the development of RZAB for practical applications.

ZnFe2O4 nanorods encapsulated in reduced graphene oxide sheets as advanced electrodes for supercapacitor applications

ZnFe2O4 nanorods encapsulated in reduced graphene oxide sheets as advanced electrodes for supercapacitor applications

A self-assembled carbon nanotube/silicon composite battery anode stabilized with chemically reduced graphene oxide sheets

This study presents a streamlined fabrication process for lithium-ion battery (LIB) electrodes, involving the dispersion of carbon nanotubes (CNT), silicon (Si), and graphene oxide (GO) in an aqueous solution, followed by vacuum filtration to produce self-standing composite electrodes. Two reduction routes are employed to form reduced graphene oxide (rGO). The chemically reduced CNT/Si/rGO-5 %-Chem anode exhibits superior mechanical resilience compared to thermally reduced counterparts, which suffer from reduced strength and structural integrity. Chemical reduction also enhances electrochemical performance, increasing the initial capacity of the non-reduced CNT/Si/GO-5 % composite anode from 1,461 to 2,342 mAh g−1, with improved long-term cycling performance. Electrochemical impedance spectroscopy shows lower pre-cycle charge transfer resistance (148 Ω) and superior solid electrolyte interphase (SEI) resistance (43 Ω) for chemically reduced anodes compared to thermally reduced ones. After cycling, the chemically reduced composite anode exhibits reduced electrolyte resistance and charge transfer resistance, indicating stable electrochemical reactions. The composite structure undergoes adaptive rearrangements during cycling, optimizing active material utilization. In summary, CNTs accommodate silicon swelling, while chemically reduced rGO promotes stable SEI formation, highlighting the benefits of chemical reduction in enhancing mechanical durability and electrochemical performance, making the self-standing CNT/Si/rGO composite film a promising LIB anode.

Interconnected CoNi-Se Hollow Flakes through Reduced Graphene Oxide Sheets as a Cathode Material for Hybrid Supercapacitors.

Achieving a high energy density and long-cycle stability in energy storage devices demands competent electrochemical performance, often contingent on the innovative structural design of materials under investigation. This study explores the potential of transition metal selenide (TMSe), known for its remarkable activity, electronic conductivity, and stability in energy storage and conversion applications. The innovation lies in constructing hollow structures of binary metal selenide (CoNi-Se) at the surface of reduced graphene oxide (rGO) arranged in a three-dimensional (3D) morphology (CoNi-Se/rGO). The 3D interconnected rGO architecture works as a microcurrent collector, while porous CoNi-Se sheets originate the active redox centers. Electrochemical analysis of CoNi-Se/rGO based-electrode reveals a distinct faradic behavior, thereby resulting in a specific capacitance of 2957 F g-1 (1478.5 C g-1), surpassing the bare CoNi-Se with a value of 2149 F g-1 (1074.5 C g-1) at a current density of 1 A g-1. Both materials exhibit exceptional high-rate capabilities, retaining 83% of capacitance at 10 A g-1 compared to 1 A g-1. In a two-electrode coin cell system, the device achieves a high energy density of 73 Wh kg-1 at a power density of 1500 W kg-1, stating an impressive 90.4% capacitance retention even after enduring 20,000 cycles. This study underscores the CoNi-Se/rGO composite's promise as a superior electrode material for high-performance energy storage applications.

Hierarchical biocide-free silicone/graphene-silicon carbide nanocomposite coatings for marine antifouling and superhydrophobicity of ship hulls

A new series of fluorine-free, nonbiocidal, and hierarchical superhydrophobic silicone coatings filled with reduced graphene oxide (RGO)/β-SiC bamboo-like nanocomposites was successfully fabricated as durable ternary marine fouling release (FR) surfaces. RGO/β-SiC hybrid was used as coating nanofiller that would release fouling and confer surface robustness. It was facilely created using a straightforward one-phase ultrasonication technique. The dispersion of different concentrations of RGO sheets decorated with β-SiC bamboo-like fillers was determined to study the superhydrophobicity and antifouling behaviors of polysiloxane nanocomposites. RGO was prepared through a simple hydrothermal technique. Solution casting was used to distribute the RGO/β-SiC nanofillers throughout a silicone matrix. Atomic force microscopy, surface free energy, and water contact angle (WCA) were employed to examine the superhydrophobicity and micro/nanoroughness of the coatings. The mechanical, anticorrosive, and durability characteristics of the silicone-RGO/β-SiC-filled composites were also investigated. The antifouling effects of the coating systems were evaluated in the laboratory for 30 days with specific bacteria. The silicone-RGO/β-SiC (3 wt%) composite with the best dispersion, highest WCA (156°), and lowest surface free energy (12.7 mN/m) among the composites exhibited favorable FR characteristics. The well-dispersed PDMS-RGO/β-SiC (3 wt% nanofiller) composite presented the minimum degradation and cell viability percentages against Gram-positive and Gram-negative bacteria as well as diatoms. Therefore, this study produced a series of nonstick and fluorine-free ternary FR nanocomposites for maritime coatings with surface durability, superhydrophobicity, and fouling retardancy. This work highlights the design and preparation of multifunctional marine nanocoatings with excellent antifouling performance, easy applicability, and superhydrophobicity properties.

Controlled synthesis of reduced graphene oxide-supported bimetallic Pt–Au nanoparticles for enhanced electrooxidation of methanol

Controlled construction of bimetallic interfaces on conductive carbon supports is extremely important for achieving better synergistic effect required for electrooxidation of small organic molecules for energy applications. Herein, controlled synthesis of reduced graphene oxide (RGO)-supported bimetallic Pt–Au nanoparticles (Pt–Au/RGO) for electrooxidation of methanol using a facile and practical approach was described. By carefully adapting sequential and simultaneous reduction steps H2PtCl6 and AuCl3were reduced on RGO support using ammonia borane (AB) and ascorbic acid (AA) as reducing agents. Three types of Pt–Au/RGO catalysts were prepared and labeled as PtAu/RGO-AB1, PtAu/RGO-AB, and PtAu/RGO-AA. The reduction process was carried at ambient conditions, without the use of surfactants, and the catalysts obtained were analyzed through various techniques, including X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), and energy dispersive X-ray spectroscopy (EDS). The PtAu/RGO-AB1 catalyst showed remarkable uniformity on the RGO sheets, with an average particle size of 2–3 nm. The electrochemical behavior of Pt–Au catalysts supported on reduced graphene oxide (RGO) for methanol oxidation was systematically investigated via cyclic voltammetry and chronoamperometry techniques. Among the studied catalysts, PtAu/RGO-AB1 exhibited high electrochemical active surface area (ECSA) of 92.47 m2/g, along with the highest mass and ECSA-normalized activities for the electrooxidation of methanol. PtAu/RGO-AB1 manifested exceptional resistance to accumulated CO-like species, as evidenced by its higher forward peak current density to reverse peak current density ratio (If/Ib) of 2.20. The facile and effective synthesis strategy described here provides a promising method for fabricating well-defined multi-component nanostructured electrocatalysts with potential applications for various fuel cell reactions.

Hetero-epitaxial grown Pt@Au core-shell bimetallic nanoparticles on reduced graphene oxide (RGO) as electrocatalyst for oxygen reduction reaction in alkaline media

The core-shell structured Pt@Aubimetallic nanoparticles (NPs) were decorated on the reduced graphene oxide (RGO) surface by a heteroepitaxial growth method. The morphological details of Pt@Au/RGO core/shell bimetallic NPs were assessed by high-resolution transmission electron microscopy (HR-TEM), x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDS). Electron microscopy results revealed that Pt@Au particles of 3.4 nm were firmly attached to RGO sheets. The electrochemical response of Pt@Au/RGO nanostructured electrocatalyst was measured through cyclic voltammetry (CV) at room temperature in 0.1 M KOH solution. Oxygen reduction reaction (ORR) efficacies of Pt@Au/RGO were evaluated by linear sweep voltammetry (LSV) by rotating catalyst-coated glassy carbon (GC) electrode at different rotation speeds in oxygen saturated 0.1 M KOH solution. The electrochemical activity descriptors (half-wave potential, onset potential, limiting current density) were assessed from ORR polarisation curves. The results revealed that Pt@Au/RGO bimetallic NPs showed enhanced higher catalytic activity towards ORR compared to commercial Pt/C catalyst as well as similarly synthesised Pt/RGO and Au/RGO. The enhanced catalytic activity of Pt@Au/RGO electrocatalyst might result from the core/shell structure with a tiny Pt core and a thin Au shell, as well as the synergistic effects of Au and Pt.

High-energy-density zinc ion capacitors based on 3D porous free-standing defect-reduced graphene oxide hydrogel cathodes.

Zinc ion capacitors (ZICs) have shown potential for breaking the energy density ceiling of traditional supercapacitors (SCs) via appropriate device design. Nevertheless, a significant challenge remains in advancing ZIC positive electrode materials with excellent conductivity, high specific capacitance, and reliable cycle stability. A highly attractive option for carbon-based electrode materials is reduced graphene oxide (RGO) due to its vast specific surface area, prominent porosity, and 3D cross-linked frame. However, the tight stacking of RGO sheets driven by van der Waals forces can restrict active sites, decrease specific capacitance, and elevate electrochemical impedance. To overcome these challenges, 3D defective RGO (DRGO) hydrogels were prepared by a metal Co cocatalytic gasification reaction. This method produced mesoporous defects on the surface of RGO hydrogels via a low-temperature hydrothermal self-assembly strategy. The surface of the layer has a wide and uniform distribution, which can offer abundant redox active sites, rich ion transfer channels, and fast reaction kinetics. In this work, 3D DRGO//Zn exhibited a wide operating window (0-1.8 V), high specific capacitance (189.39 F g-1 at 1 A g-1), outstanding energy density (85.23 W h kg-1 at 960.31 W kg-1; 52.36 W h kg-1 at 17454.87 W kg-1), and persistent cycling life (98.86% initial capacitance retention after 10 000 cycles at 10 A g-1). This study emphasizes the device design of ZIC and promising prospects of using 3D DRGO hydrogel as a feasible positive electrode for ZIC.

Fe3O4 nanoparticles decorated reduced graphene oxide&carbon nanotubes-based composite for sensitive detection of imatinib in plasma and urine

In this study, a new reduced graphene oxide (rGO) has been synthesized via a facile and envi­ronmentally friendly process using Callicarpa maingayi leaf extract. A novel magnetic catalyst based on Fe3O4 nanoparticles-reduced graphene oxide&carbon nanotubes ((Fe3O4--(rGO&CNT)) was prepared and characterized by hydrothermal method. The Fe3O4 nanoparticles with an average size of 25 to 40 nm were placed on carbon nanotubes and reduced graphene oxide sheets, while carbon nanotubes inserted between the reduced graphene oxide sheets effectively prevented their aggregation. The (Fe3O4-(rGO&CNT) composite has a large surface area and good electrocatalytic properties, suiting for the detection and determination of imatinib (IM) anticancer drug by voltammetry method. Under opti­mi­zed conditions, good linearity was achieved in the concentration range of 0.1 to 40 μmol L-1 and the limit of detection and sensitivity were 57 nmol L-1 and 3.365 μA L μmol-1, respectively. Furthermore, the fabricated sensor demonstrated acceptable reproducible behaviour and accuracy and a high level of stability during all electrochemical tests. In addition, the proposed method was applied for the detection of IM in biological samples and the recoveries were 94.0 to 98.5 %, with relative standard deviations of 2.1 to 4.4 %.

Well-organized metal-free chemically reduced graphene oxide sheets as electrocatalysts for enhanced oxygen reduction reactions in alkaline media

Metal-free reduced graphene oxides have recently received attention as potential replacements for platinum-based electrocatalysts. In the present study, we investigated the electrochemical characteristics of chemically reduced graphene oxides (C-rGO) in oxygen reduction reactions (ORR). The C-rGO displays significantly enhanced catalytic activity towards the ORR in alkaline solutions compared to the starting graphene oxide (GO). The thermal properties of C-rGO show good thermal stability, and structural defects in C-rGO were confirmed by Raman analysis. Electrochemical impedance spectroscopy (ESI) analysis confirmed C-rGO superior electron transport capacity over GO. The onset potential (0.82 V), lower Tafel slope, and current density (-5.6 × 10-4 mA/cm2) of the C-rGO catalysts were increased compared to GO due to the majority of functional groups removed after chemical reductions. It's clear that catalysts work through four electron (e-) ORR processes bacause the C-rGO has higher electron transfer numbers (3.8 at a potential of −0.63 V).

Insitu assembly of Fe3O4@FeNi3 spherical mesoporous nanoparticles embedded on 2D reduced graphene oxide (RGO) layers as protective barrier for EMI pollution

Electromagnetic interference (EMI) is a major issue due to the increased use of electronic devices operating in the gigahertz frequency range. Consequently, to reduce electromagnetic pollution, materials with considerable magnetic and dielectric loss can be used for the attenuation of electromagnetic waves. In this paper, Fe3O4 FeNi3 spherical mesoporous nanoparticles embedded on reduced graphene oxide (RGO) layers have been synthesized using the hydrothermal reduction method. The specific surface area of Fe3O4@FeNi3/RGO nanocomposite was 67.4 m2/g with a pore size diameter of 3.4 nm (i.e., mesoporous range). Fe3O4@FeNi3/RGO nanocomposites show an enhanced absorption dominant shielding effectiveness (SE) value of 46.49 dB as compared to its binary counterpart Fe3O4@FeNi3, having SE value of 25.21 dB. The synthesized Fe3O4@FeNi3/RGO nanocomposite of thickness 1.42 mm has SER of ∼10.32 dB and SEA of ∼36.15 dB at 15 GHz. Furthermore, it is observed that shielding efficiency increases with increasing reduced graphene oxide (RGO) content in Fe3O4@FeNi3, which is owing to an excellent interconnected network between RGO and Fe3O4@FeNi3. The RGO sheets can create a comprehensive conductive network for the distribution of charges and can enhance dielectric loss because of the layered structure, greater specific surface area and large aspect ratio. Additionally, the mesoporous Fe3O4@FeNi3 hybrid embellished on the surface of RGO may be employed as a multi-pole polarisation centre, enhancing the electronic and space charge polarization of the composites, which is helpful for strong EM wave absorption. It was believed that these nanocomposites would pave the way for the development of RGO-based mesoporous nanocomposites as broadband, lightweight and effective shielding material for practical applications.

Construction of FeSbO4-Sb2O4 hetero-nanocrystals anchored on reduced graphene oxide sheets for superior lithium and sodium storage

Antimony-based oxides with conversion-alloying/dealloying mechanism have attracted great attentions as alternative anode materials for lithium/sodium-ion batteries due to their high theoretical capacities. However, slow reaction kinetics, inherent poor conductivity and large volume change severely inhibit their practical application. Herein, a novel composite with FeSbO4-Sb2O4 hetero-nanocrystals anchored on reduced graphene oxide (rGO) sheets is designed and successfully constructed by a facile solvothermal method. The intense interaction between Fe3+ and Sb5+ oxidized from Sb3+ by graphene oxide (GO) boosts priority formation of rutile FeSbO4 nanoparticles. And the excess Sb3+ and Sb5+ subsequently generate nano-sized cervantite Sb2O4 to form FeSbO4-Sb2O4 hetero-interface. Such unique structure not only can enhance electrical conductivity and structural stability of electrode, but also shorten diffusion distance of lithium/sodium ions during discharge/charge processes. Moreover, the in-situ generated Fe during electrochemical reaction can boost lithium/sodium release from Li2O/Na2O. Attributed to the unique structure, the as-obtained FeSbO4-Sb2O4/rGO-200 electrode delivers greatly improved electrochemical performance for both lithium and sodium storage, including large reversible capacities, high rate capability, and superior long-term cycling stability. This work provides an efficient route to rationally design and synthesize hetero-structural composites boosting lithium-/sodium-storage properties.

Functionalization and Crosslinking of Reduced Graphene Oxide Sheets by Multiple Tetrazine Units to Improve the Energy Storage in Supercapacitors

AbstractA multi‐tetrazine compound tailored for grafting on graphene sheets has been designed and investigated. It is composed of hydrogen substituted tetrazines involved in inverse Diels‐Alder demand cycloaddition reactions for grafting and a central dialkoxytetrazine to confer redox properties to the final material. The successful incorporation of this compound in reduced graphene oxide was demonstrated by elemental analysis, XPS, Raman spectroscopy, AFM, SEM and XRD. Cyclic voltammetry shows the redox activity of the remaining central tetrazine unit in graphene and allows to assess the specific capacity of the material. A significant increase in the specific capacity was found compared to pristine graphene and another tetrazine model compound bearing only one grafting unit. This result was assigned to an increase in the specific area in relation to bridges created between graphene sheets, as evidenced by AFM and XRD. The performance in energy storage were assessed in symmetrical Swagelok cells confirming the high impact of the functionalization on capacitance values.

Goethite (α-FeOOH) nanoparticles wrapped on reduced graphene oxide nanosheet for sensitive electrochemical detection of arsenic(III)

The goethite (α-FeOOH) nanoparticles were wrapped on the reduced graphene oxide (rGO) to synthesize the α-FeOOH/rGO nanocomposites. The nanocomposites (NCs) were initially examined for their optical, structural, and morphological properties. The XRD data obtained the crystallite size of the α-FeOOH, showed that the average crystal size for pristine α-FeOOH and α-FeOOH/rGO nanocomposites were about 85 and 90 nm, respectively. The transmission electron microscope confirmed the nanoparticles (NPs) were evenly distributed throughout the reduced graphene oxide sheets. The nanocomposites improved glassy carbon electrodes (GCE), making them efficient sensors for detecting the arsenic(III) (As+3) in a pH 5 phosphate buffer solution with an Ag/AgCl reference electrode. The detection limit for As+3 was 0.07 μgL−1 and the resulting sensitivity was 0.39 μA−1 μgL−1 in the linear dynamic range of 0.1–10 μgL−1. The α-FeOOH/rGO/GCE was more sensitive than its original and showed a synergistic effect due to the influence of α-FeOOH on the properties of rGO. The α-FeOOH/rGO NCs-modified GCE electrode performed as a promising sensor, by separating the common interfering ions. Moreover, the modified electrode exhibited remarkable stability, repeatability, and potential real-time application towards the detection of arsenic(III). Additionally, the proposed approach has been successfully applied to the detection of As+3 in the real water sample.

A redox additive electrolyte boosted supercapacitive energy density of wrinkled RGO sheets

Redox additive (RA)-based electrolytes have emerged as a promising approach to enhance the performance of carbon-based supercapacitors (SCs) as they bestow the additional pseudocapacitance to carbon and enhance its energy density (Ed). The present study demonstrates the enhanced supercapacitive Ed of reduced graphene oxide (RGO) electrodes by employing an RA of 0.05 M K4[Fe(CN)6] (KFC) in 0.5 M K2SO4 (K2) electrolytes. To enhance the active surface area (confirmed by N2 absorption- desorption) with minor agglomeration (confirmed by morphological analysis) and less defective (confirmed by Raman analysis) wrinkled RGO sheets were synthesized through thermal reduction of GO. The RGO electrode obtained 3 times higher specific capacitance (CS) in K2+ KFC as compared to the K2 electrolyte. The assembled RGO-based symmetric aqueous device shows CS of 79.5 F/g and 66 mAh/g of specific capacity (CPS) at 5 mV/s with 36.8 Wh/kg Ed, 1.2 kW/kg of Pd at 15 mA, and 134 % capacitance retention over 5000 galvanostatic charge-discharge cycles in K2 + KFC electrolyte. The obtained results demonstrated the incorporation of a tiny amount of RA in supporting electrolytes can significantly enhance the electrochemical performance and pave the way for future advanced energy storage technology.

Tuning the porous graphene interlayer structure for compact energy storage towards high volumetric performance of Zn-ion capacitor

For most consumer electronics, the volumetric performance of energy storage devices is usually more significant than traditional gravimetric performance. Zinc-ion capacitors (ZICs) are regarded as one of the most promising energy storage devices with high energy and power density. However, the low volumetric performance of the cathode is a serious problem that hinders its practical application. Herein, in this work, a compact freestanding graphene film was designed by tuning the interlayer structure of flame reduced graphene oxide sheets (FRGO) using graphene oxides (GO) via a self-assembly strategy. When the mass ratio of FRGO and GO is 75%:25%, the optimum of graphene film between density and electrochemical performance was achieved. The graphene film owns a bulk density of 0.82 g cm−3 and precisely regulated abundant mesoporous around 3.8 nm, which provides more active sites for ion storage. Profiting from the pseudocapacitance reaction between C=O and Zn2+, the compact graphene film with a thickness of 35 μm as ZICs cathode can deliver a high volumetric energy density of 113.1 Wh L-1 and outstanding gravimetric performance of 118.7 Wh kg−1 with a bulk density of 0.95 g cm−3, achieving the balance of the gravimetric and volumetric characteristics. The ZIC also presents a maximum volumetric power density of 21.2 kW L-1 at 7.9 Wh L-1 and 96.4% capacity retention after 8000 cycles, revealing excellent compact energy storage and cyclability. Moreover, the soft-package ZIC devices present admirable scalability, further exposing the application potential of the compact graphene film in the ZIC field.

Preparation and characterization of ball milled hexagonal‑boron nitride (BMBN) and fluorescein (FL) decorated reduced graphene oxide (RGO) nanocomposite towards toxic heavy metal ion detection

In the present work, a novel hybrid fluorescent nanocomposite (RBF) based on ball milled hexagonal-Boron Nitride (BMBN) and Fluorescein (FL) decorated reduced Graphene Oxide (RGO) was synthesized for the effective detection and removal of hazardous heavy metal ions present in effluents. Where two different textile effluents namely, reaction outlet and factory outlet collected at the river Noyyel, Tamilnadu were considered. The prepared RBF was subjected to XRD, FTIR, SEM, EDX, TEM, PSA, BET, UV–vis, PL and XPS studies which strongly confirm the decoration of FL and BMBN at the surface of RGO sheets. The selectivity of RBF was examined by considering various toxic heavy metal ions. Where the RBF exhibits remarkable sensing towards Zn2+ (10.7 nM) via enhanced fluorescence and for Fe3+ (15.6 nM), Sn4+ (60.7 nM) and Hg2+ (465.4 nM) ions by “Turn-off” fluorescence only at neutral pH. In addition, the RBF was highly efficient to remove Hg (81.3 %) than Zn (63.7 %), Fe (38.2 %) and Sn (62.9 %) in real-time samples. Moreover, the prepared RBF could also serve as water sensor for the water contaminated organic solvents of Acetonitrile (ACN) and Tetrahydrofuran (THF). Hence the prepared RBF might be a potential choice for the effective detection and removal of heavy metal ions during wastewater treatment.

Ni Nanoparticles on the Reduced Graphene Oxide Surface Synthesized in Supercritical Isopropanol.

Nanocomposites based on ferromagnetic nickel nanoparticles and graphene-related materials are actively used in various practical applications such as catalysis, sensors, sorption, etc. Therefore, maintaining their dispersity and homogeneity during deposition onto the reduced graphene oxide substrate surface is of crucial importance to provide the required product characteristics. This paper demonstrates a new, reproducible method for preparing a tailored composite based on nickel nanoparticles on the reduced graphene oxide surface using supercritical isopropanol treatment. It has been shown that when a graphene oxide film with previously incorporated Ni2+ salt is treated with isopropanol at supercritical conditions, nickel (2+) is reduced to Ni (0), with simultaneous deoxygenation of the graphene oxide substrate. The resulting composite is a solid film exhibiting magnetic properties. XRD, FTIR, Raman, TEM, and HRTEM methods were used to study all the obtained materials. It was shown that nickel nanoparticles on the surface of the reduced graphene oxide had an average diameter of 27 nm and were gradually distributed on the surface of reduced graphene oxide sheets. The data obtained allowed us to conduct a reconnaissance discussion of the mechanism of composite fabrication in supercritical isopropanol.

Functionalized Reduced Graphene Oxide Sheets: An Efficient Resistive Sensing Platform for Arsenic

Functionalized Reduced Graphene Oxide Sheets: An Efficient Resistive Sensing Platform for Arsenic