Graphene Oxide Nanohybrid Research Articles

Synthesis and characterization of novel magnetic Zr-MnFe2O4@rGO nanohybrid for efficient removal of PFOA and PFOS from aqueous solutions

The emerging contaminants such as perfluorinated chemicals (PFCs) have been observed of increasing concerns throughout the world due to their detrimental effects for human health and other creatures in nature. Herein, zirconium imprinted magnetic manganese ferrite assembled reduced graphene oxide (rGO) nanohybrids were used to remove perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). The effective intercalation of magnetic Zr-MnFe2O4 into rGO was confirmed from FTIR, PXRD, VSM, and Raman spectra. Surface morphologies and particle sizes of as-synthesized adsorbents were determined using FE-SEM, HR-TEM, EDX, and BET analysis. Several factors including contact time, pH, initial concentrations of PFOA and PFOS, type of coexisting anions, and presence of other organic compounds were optimized to determine the maximum density of the prepared Zr-MnFe2O4@rGO nanohybrids. The adsorption of PFOA and PFOS on the Zr-MnFe2O4@rGO nanohybrids was governed mainly by electrostatic attraction followed by hydrophobic interaction. In particular, the treated adsorbents could be easily separated by employing external magnetic force, and it could be regenerated and reused up to four cycles without any significant loss. The Zr-MnFe2O4@rGO nanohybrids are potential candidates for the removal of PFOA and PFOS from aqueous environment.

Iron oxide/gold nanoparticles-decorated reduced graphene oxide nanohybrid as the thermo-radiotherapy agent.

The main focus of the current study is the fabrication of a multifunctional nanohybrid based on graphene oxide (GO)/iron oxide/gold nanoparticles (NPs) as the combinatorial cancer treatment agent. Gold and iron oxide NPs formed on the GONPs via the in situ synthesis approach. The characterisations showed that gold and iron oxide NPs formed onto the GO. Cell toxicity assessment revealed that the fabricated nanohybrid exhibited negligible toxicity against MCF-7 cells in low doses (<50 ppm). Temperature measurement showed a time and dose-dependent heat elevation under the interaction of the nanohybrid with the radio frequency (RF) wave. The highest temperature was recorded using 200 ppm concentration nanohybrid during 40 min exposure. The combinatorial treatments demonstrated that the maximum cell death (average of 53%) was induced with the combination of the nanohybrid with RF waves and radiotherapy (RT). The mechanistic study using the flow cytometry technique illustrated that early apoptosis was the main underlying cell death. Moreover, the dose enhancement factor of 1.63 and 2.63 were obtained from RT and RF, respectively. To sum up, the authors' findings indicated that the prepared nanohybrid could be considered as multifunctional and combinatorial cancer therapy agents.

Sonochemical assisted synthesis of manganese–nickel molybdate/reduced graphene oxide nanohybrid for energy storage

Abstract In the present study, manganese-nickel molybdate was synthesized using an ultrasonic assisted method for the first time. The hybrid of reduced graphene oxide (RGO) with manganese-nickel molybdate was also prepared. The structure of nanohybrid was characterized by Raman spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and inductively coupled plasma optical emission spectrometry (ICP-OES). Field emission scanning electron microscopy images showed that the manganese-nickel molybdate has the nanorod morphology. In addition, transmission electron microscopy images confirmed the presence of reduced RGO nanosheets in the nanohybrid. From ICP-OES, the nanohybrid formula was obtained as Mn0.63Ni0.37MoO4-RGO. Some electrodes with different RGO weight ratios were also prepared on nickel foam (NF) plates. Cyclic voltammetry studies showed that nanohybrid has typical faradaic redox behavior in 2 M KOH. Additionally, galvanostatic investigations showed that Mn0.67Ni0.37MoO4- RGO (60 wt %) nanohybrid can provide the high specific capacity of 161.1 mA h g−1 at 2 A g−1, which is higher than that for MnMoO4-RGO and NiMoO4-RGO nanohybrids. Furthermore, the electrode based on Mn0.67Ni0.37MoO4 provided higher specific capacity than that for MnMoO4 or NiMoO4. Owing to the synergistic effect of both Mn and Ni elements with RGO in nanohybrid, the Mn0.67Ni0.37MoO4-RGO showed the high energy density of 87 W h kg−1 at 1080 W kg−1 and the power density of 8640 W kg−1 at 9.6 W h kg−1. The electrode provided the cyclic stability about 92% of its initial capacity after 2000 cycles at 50 mV s−1. Our results showed the successful synthesis of manganese-nickel molybdate/RGO nanohybrid for the potential use in energy storage systems.

Polystyrene/thermoplastic polyurethane interpenetrating network-based nanocomposite with high-speed, thermo-responsive shape memory behavior

In the recent years, generation of flexible, mechanically tough, shape memory (SM) polymers has gained a remarkable significance both in academic section and in the field of soft robotics, smart textiles, self-deployable structures (especially used in aerospace), actuators, bio-medical devices and so on. But designing of such materials poses a credible challenge to researchers in the field. Hence, in this work, we develop a bis(hydroxyalkyl)-poly(dimethylsiloxane) capped-(3-aminopropyl)trimethoxysilane functionalized-hydroxy iron oxide anchored-reduced graphene oxide nanohybrid which serves as a reinforcing agent for the generation of nanocomposites with SM, self-tightening and hydrophobic attributes. The prepared polystyrene/thermoplastic polyurethane (PS/TPU) interpenetrating network (IPN) nanocomposites recover their original shape at a faster rate (within 20–40s upon thermal heating and within 100–140s upon exposure to sunlight) compared to other similar type SM materials (require h to min). Moreover, the nanocomposites also showed thermally actuated artificial muscle-like and self-tightening behaviors. In addition, the nanocomposite containing 1 wt% nanohybrid demonstrated >200% increase in tensile strength, >120% increase in initial thermal degradation temperature, and strong surface hydrophobicity (static contact angle >120°). Therefore, the reported nanocomposites have considerable prospect for different smart applications.

One-step synthesis of zwitterionic\xa0graphene oxide nanohybrid: Application to polysulfone tight ultrafiltration hollow fiber membrane

In this paper, novel zwitterionic graphene oxide (GO) nanohybrid was synthesized using monomers [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBMA) and N,N′-methylenebis(acrylamide) (MBAAm) (GO@poly(SBMA-co-MBAAm), and incorporated into polysulfone (PSF) hollow fiber membrane for the effectual rejection of dye from the wastewater. The synthesized nanohybrid was characterized using FT-IR, PXRD, TGA, EDX, TEM and zeta potential analysis. The occurrence of nanohybrid on the membrane matrix and the elemental composition were analyzed by XPS. The as-prepared tight ultrafiltration hollow fiber membrane exhibited high rejection of reactive black 5 (RB-5, 99%) and reactive orange 16 (RO-16, 74%) at a dye concentration of 10 ppm and pure water flux (PWF) of 49.6 L/m2h. Fabricated nanocomposite membranes were also studied for their efficacy in the removal of both monovalent (NaCl) and divalent salts (Na2SO4). The results revealed that the membrane possesses complete permeation to NaCl with less rejection of Na2SO4 (<5%). In addition, the nanocomposite membrane revealed outstanding antifouling performance with the flux recovery ratio (FRR) of 73% towards bovine serum albumin (BSA). Therefore, the in-house prepared novel nanocomposite membrane is a good candidate for the effective decolorization of wastewater containing dye.

Accelerated photocatalytic degradation of organic pollutants over carbonate-rich lanthanum-substituted zinc spinel ferrite assembled reduced graphene oxide by ultraviolet (UV)-activated persulfate

Abstract Carbonate-rich lanthanum-substituted zinc spinel ferrite assembled reduced graphene oxide nanohybrids (LaZF@rGO) were simply synthesized using a simple hydrothermal-induced precipitation process. The synthesized photocatalytic material, LaZF@rGO, showed excellent photocatalytic performance in the decolorization and mineralization of rhodamine B (RhB) under ultraviolet (UV) irradiation with the aid of peroxydisulfate. The photocatalytic activity of the optimized LaZF@rGO nanohybrids was approximately two times higher than that of zinc spinel ferrite assembled reduced graphene oxide, suggesting the critical role of lanthanum in assisting the peroxydisulfate degradation of RhB. The prepared photocatalyst was successfully utilized in the removal of a wide spectrum of selected organic contaminants such as charged dyes and pharmaceutical and personal care products under UV irradiation. The obtained “green” photocatalyst has a great potential for practical applications, since it can be regenerated and reused at least four times with negligible loss of photocatalytic activity and with insignificant leaching of potentially hazardous toxic elements (e.g., lanthanum and zinc) to the environment.

Label-free assay of protein kinase A activity and inhibition in cancer cell using electrochemically-prepared AuNP/rGO nanohybrid electrode modified with C-Kemptide

A simple, label-free and sensitive electrochemical assay is described for the detection of protein kinase A (PKA) activity and inhibition in cancer cell by measuring the change in electrochemical impedance upon phosphorylation. The assay utilized gold nanoparticle (AuNP) and reduced graphene oxide (rGO) nanohybrid which was synthesized and deposited on the electrode from GO and Au3+ precursors by one-pot electrochemical synthesis. As-prepared AuNP/rGO electrode was employed to immobilize C-Kemptide peptide substrates which was phosphorylated in the presence of PKA and ATP. The resulting assay allowed effective, selective and sensitive monitoring of PKA activity according to the impedimetric change in the range of 0.1–500 U/mL, and the detection limit (LOD) is 53 mU/mL. It could also be used for the screening of protein kinase inhibitors. Furthermore, the assay could be applied for the evaluation of PKA activity and inhibition in HeLa cell samples. Therefore, the proposed assay provides one promising tool for PKA activity detection and inhibitor screening with excellent performance.

Antibacterial activity and long-term stable antibacterial performance of nisin grafted magnetic GO nanohybrids.

In this study, magnetic graphene oxide (MGO) nanohybrids were firstly fabricated by loading Fe3O4 NPs onto GO nanosheets and then novel nisin grafted MGO (nisin-g-MGO) nanohybrids were prepared by a facile method. The nisin-g-MGO nanohybrids exhibit strong enough magnetic separation capacity. The magnetic saturation (Ms) of nisin-g-MGO nanohybrids was 23.3emu/g that enables nisin-g-MGO nanohybrids can be rapidly and completely separated from the black and stable suspension by an external magnet. The antibacterial studies of nisin-g-MGO nanohybrids show great antibacterial performance against Staphylococcus aureus and Bacillus subtilis, respectively. Moreover, the nisin-g-MGO nanohybrids exhibit long-term antibacterial stability that they still keep their good antibacterial activity after six months storage. Meanwhile, the fabricated nisin-g-MGO nanohybrids exhibit good biocompatibility without any obvious effect on HEK293 cell viability due to the calculated cell viabilities were more than 95%. And no observed changes in cell morphology were found in nisin-g-MGO nanohybrids treated HEK293 cells. Hence, the fabricated nisin-g-MGO nanohybrids exhibit great potentials in antibacterial application.

Electrochemical energy storage properties studies of Cu0.2Ni0.8O-Reduced graphene oxide nano-hybrids

Cu0.2Ni0.8O nano-particles and their nano-hybrids were synthesized by wet chemical methods and examined by X-ray diffraction (XRD) technique, spectroscopic analysis, Field Emission scanning electron microscopic (FESEM) technique and energy dispersive x-rays (EDX) analysis. XRD results confirmed that the synthesized materials were crystallite in the cubic phase of Cu0.2Ni0.8O nano-particles annealed at 500 and 800 °C. The crystallite size synthesized product was found to be around 5–20 nm. FTIR and EDX results were supporting XRD data. Morphological studies represented the spherical nature of Cu0.2Ni0.8O nano-particles annealed at 500 and 800 °C with particle size <70 nm. Electrochemical measurements of Cu0.2Ni0.8O nano-particles annealed at 500 and 800 °C and their nano-hybrids were also performed. Brilliant specific capacitance (303 F g-1) was observed in the case of rGO-based nano-hybrid of Cu0.2Ni0.8O nano-particles annealed at 500 °C. This additional noted specific capacitance was credited to more conducting nature and relatively high surface area of graphene.

Titania/Electro-Reduced Graphene Oxide Nanohybrid as an Efficient Electrochemical Sensor for the Determination of Allura Red.

Titania/electro-reduced graphene oxide nanohybrids (TiO2/ErGO) were synthesized by the hydrolysis of titanium sulfate in graphene oxide suspension and in situ electrochemical reduction. It provides a facile and efficient method to obtain nanohybrids with TiO2 nanoparticles (TiO2 NPs) uniformly coated by graphene nanoflakes. TiO2/ErGO nanohybrids were characterized by transmission electron microscopy, X-ray diffraction, cyclic voltammogram, and electrochemical impedance spectroscopy in detail. Compared with pure ErGO and TiO2 NPs, TiO2/ErGO nanohybrids greatly enhanced the electrocatalytic activity and voltammetric response of Allura Red. In the concentration range of 0.5–5.0 μM, the anodic peak currents of Allura Red were linearly correlated to their concentrations. However, the linear relationship was changed to the semi-logarithmic relationship at a higher concentration region (5.0–800 μM). The detection limit (LOD) was 0.05 μM at a signal-to-noise ratio of 3. The superior sensing performances of the proposed sensor can be ascribed to the synergistic effect between TiO2 NPs and ErGO, which provides a favorable microenvironment for the electrochemical oxidation of Allura Red. The proposed TiO2/ErGO/GCE showed good reproducibility and stability both in determination and in storage, and it can accurately detect the concentration of Allura Red in milk drinks, providing an efficient platform for the sensitive determination of Allura Red with high reliability, simplicity, and rapidness.

Zirconia Reduced Graphene Oxide Nano-Hybrid Structure Fabricated by the Hydrothermal Reaction Method.

In this work, we report an available technique for the effective reduction of graphene oxide (GO) and the fabrication of nanostructured zirconia reduced graphene oxide powder via a hydrothermal method. Characterization of the obtained nano-hybrid structure materials was carried out using a scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR). The confirmation that GO was reduced and the uniform distribution of zirconia nanoparticles on graphene oxide sheets during synthesis was obtained due to these techniques. This has presented new opportunities and prospects to use this uncomplicated and inexpensive technique for the development of zirconia/graphene nanocomposite powders.

Shedding Light Onto the Nature of Iron Decorated Graphene and Graphite Oxide Nanohybrids for CO2 Conversion at Atmospheric Pressure.

We report on the design and testing of new graphite and graphene oxide‐based extended π‐conjugated synthetic scaffolds for applications in sustainable chemistry transformations. Nanoparticle‐functionalised carbonaceous catalysts for new Fischer Tropsch and Reverse GasWater Shift (RGWS) transformations were prepared: functional graphene oxides emerged from graphite powders via an adapted Hummer's method and subsequently impregnated with uniform‐sized nanoparticles. Then the resulting nanomaterials were imaged by TEM, SEM, EDX, AFM and characterised by IR, XPS and Raman spectroscopies prior to incorporation of Pd(II) promoters and further microscopic and spectroscopic analysis. Newly synthesised 2D and 3D layered nanostructures incorporating carbon‐supported iron oxide nanoparticulate pre‐catalysts were tested, upon hydrogen reduction in situ, for the conversion of CO2 to CO as well as for the selective formation of CH4 and longer chain hydrocarbons. The reduction reaction was also carried out and the catalytic species isolated and fully characterised. The catalytic activity of a graphene oxide‐supported iron oxide pre‐catalyst converted CO2 into hydrocarbons at different temperatures (305, 335, 370 and 405 °C), and its activity compared well with that of the analogues supported on graphite oxide, the 3‐dimensional material precursor to the graphene oxide. Investigation into the use of graphene oxide as a framework for catalysis showed that it has promising activity with respect to reverse gas water shift (RWGS) reaction of CO2 to CO, even at the low levels of catalyst used and under the rather mild conditions employed at atmospheric pressure. Whilst the γ‐Fe2O3 decorated graphene oxide‐based pre‐catalyst displays fairly constant activity up to 405 °C, it was found by GC‐MS analysis to be unstable with respect to decomposition at higher temperatures. The addition of palladium as a promoter increased the activity of the iron functionalised graphite oxide in the RWGS. The activity of graphene oxide supported catalysts was found to be enhanced with respect to that of iron‐functionalised graphite oxide with, or without palladium as a promoter, and comparable to that of Fe@carbon nanotube‐based systems tested under analogous conditions. These results display a significant step forward for the catalytic activity estimations for the iron functionalised and rapidly processable and scalable graphene oxide. The hereby investigated phenomena are of particular relevance for the understanding of the intimate surface morphologies and the potential role of non‐covalent interactions in the iron oxide‐graphene oxide networks, which could inform the design of nano‐materials with performance in future sustainable catalysis applications.

Nitrogen-Doped Carbon Black/Reduced Graphene Oxide Nanohybrids for Simultaneous Electrochemical Determination of Hydroquinone and Paracetamol

By using dopamine (DA) as a functionalized and linked agent, a novel nanohybrid nitrogen-doped carbon black/reduced graphene oxide (NCB/rGO) was prepared successfully via a green three-step process in this work, and then, NCB/rGO was applied in the field of electrochemical sensing through introducing the case of simultaneous determination of two pollutants, hydroquinone (HQ) and paracetamol (PCM). The produced NCB/rGO was characterized by various technologies including transmission electron microscopy, X-ray diffraction, Raman spectroscopy and electrochemical method. Owing to the synergetic advantages from each component in nanohybrids, the results showed that the NCB/rGO nanohybrids can exhibit excellent electrochemical sensing performances and the responsive peak current of HQ and PCM at NCB/rGO electrode are ∼3.2 and 23.0 times as high as those at single CB and rGO electrode, respectively. After optimizing the detection conditions, the analytical responses of NCB/rGO modified electrode has a linear range between 0.05 and 20.0 μM for both targets with low detection limit (16.5 nM for HQ and 26.2 nM for PCM). It’s believed that the developed NCB/rGO novel nanohybrids will have important applications in electrochemical sensing of HQ and PCM as well as many other analytes.

SiO2-GO nanofillers enhance the corrosion resistance of waterborne polyurethane acrylic coatings

Corrosion to metal is a great challenge to major industries. Anticorrosive coatings can effectively prevent metal corrosion. In this study, we propose a novel method to prepare silica nanoparticles-covered graphene oxide (SiO2-GO) nanohybrids and anticorrosion SiO2-GO/waterborne polyurethane acrylic (WPUA) coatings. Firstly, we obtained silane-functionalized graphene oxide (A-GO) via a simple covalent functionalization of graphene oxide (GO) with 3-aminopropyltriethoxysilane. Secondly, SiO2-GO was synthesized by a simple sol–gel method with tetraethoxysilane in water–alcohol solution. Finally, the obtained SiO2-GO nanofillers were added into WPUA to prepare SiO2-GO/WPUA coatings. GO, A-GO, and SiO2-GO nanohybrids could be confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, and transmission electron microscope. SiO2-GO nanohybrids showed small size compared with the unfunctionalized GO. Meanwhile, GO, A-GO, and SiO2-GO nanofillers were added into WPUA. The electrochemical impedance spectroscopy and field emission scanning electron microscope indicate that SiO2-GO nanohybrids can be homogeneously dispersed in the WPUA coatings at 0.4% loading level and the SiO2-GO/WPUA film exhibits excellent anticorrosion performance. SiO2-GO nanoparticles can effectively utilize in the area of anticorrosive nanofiller industry. This study provides a convenient method of anticorrosive coating production.

Eco-friendly development of an ultrasmall IONP-loaded nanoplatform for bimodal imaging-guided cancer theranostics

Success in disease therapy depends on precision medicines, where development of formulations with diagnostic and therapeutic functions is quite important. In this study, multifunctional theranostics based on a magnetic graphene oxide (GO) nanohybrid (GIPD) has been developed for magnetic resonance (MR) imaging-guided chemo-photothermal therapy of cancer. The GIPD is endowed with T1/T2 MR imaging capacity via precipitation of small-sized IONP nanoparticles (8.25 ± 2.25 nm) on GO nanosheets through a mild friendly way (60 °C for 1 h, no organic solvent). The obtained nanocomposite is then non-covalently decorated with phosphine oxide polyethylene glycol to improve biosafety. The final nanohybrid effectively loads doxorubicin as the model chemotherapeutic drug and is found to have in vivo T1/T2 MR bimodal imaging functions. Both the in vitro and in vivo results demonstrate that the GO-based nanoplatform displays a good remote photothermal effect, which can damage the dense shell of solid tumor tissue, thereby facilitating the delivery of anticancer drugs into tumor cells. Therefore, this theranostic nanoplatform enables a potent combined chemo-photothermal anticancer efficacy, holding great potential for exploitation of precision cancer therapy.

Synthesis and Characterization of a Silver Nanoparticles-Reduced Graphene Oxide Nanohybrid by using ‘Zingiber Officinale’ Extract as a Reducing and Stabilizing Agent

An eco-friendly solution-based chemical approach has been used to prepare silver nanoparticles-reduced graphene oxide (AgNPs-rGO) nanohybrid using Zingiber officinale extract as a reducing and stabilizing agent. The products form a stable aqueous solution without any surfactant stabilizers and hence makes it possible to produce AgNPs-rGO nanohybrid on a large scale using low-cost solution processing technique. The nanohybrid was monitored at different concentration of GO solution (0.1 mg/ml, 0.5 mg/ml and 1.0 mg/ml) and characterized using UV- visible (UV-Vis) absorption spectrum, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy analyses. From the UV-Vis analysis, the formation of silver nanoparticles (AgNPs) was confirmed and showed a surface plasmon resonance (SPR) absorption band at 420 nm for nanohybrids with GO concentration of 0.5 mg/ml. Raman spectra shows an increase in ID/IG ratio for rGO with values of 1.007 corresponding to the concentration of GO (0.5mg/ml) as compared to GO (0.88). Completely spherical Ag nanoparticles (NPs) were found at a nanohybrid with 0.5 mg/ml of GO with an average particle size of 20 nm. The AgNPs-rGO(0.5) nanohybrid exhibit fast electron-transfer kinetics for electrochemical reaction of Fe (CN)63-/4- redox couple, suggesting the potential applications for electrocatalysis and electrochemical sensor. Â

High-Flux, Antifouling Hydrophilized Ultrafiltration Membranes with Tunable Charge Density Combining Sulfonated Poly(ether sulfone) and Aminated Graphene Oxide Nanohybrid.

In this work, a new protocol was developed for creating charge-tuned, hydrophilic hybrid ultrafiltration (UF) membranes with high flux, rejection rate, and fouling resistance. The membranes were fabricated using a combination of sulfonated poly(ether sulfone) (SPES) and aminated graphene (GO-SiO2-NH2) nanohybrid via the non-solvent-induced phase separation (NIPS) method. The GO-SiO2-NH2 nanohybrid was first synthesized using GO nanosheets and 3-aminopropyl triethoxysilane (APTES) through the covalent condensation reaction at 80 °C and was thoroughly characterized. Then, 2-8 wt% of the nanohybrid was incorporated into the matrix of SPES for the fabrication of the hybrid membranes. The resulting membranes were characterized using an electrokinetic analyzer, a contact angle goniometer, and Raman, field emission scanning electron microscopy-energy-dispersive X-ray spectrometry (FESEM-EDX), and atomic force microscopy experiments. The porosity, charge density, and surface morphology were altered, and the hybrid membranes became more hydrophilic after the incorporation of the nanohybrid. The pure water flux of the hybrid membranes systematically increased with the loading amount of the nanohybrid. The pure water flux of the hybrid membrane containing 6 wt% GO-SiO2-NH2 nanohybrid at a 2 bar feed pressure was 537 L m-2 h-1, about 3-fold that of pristine membrane (186 L m-2 h-1). The fouling resistance of the hybrid membranes was evaluated and confirmed using several representative foulants, including bovine serum albumin, humic acid, sodium alginate, and a synthetic solution of natural organic matter (NOM). The fabricated membranes were capable of removing more than 97% of NOM, without a compromise of their rejection rate.

Reduced graphene oxide-intercalated graphene oxide nano-hybrid for enhanced photoelectrochemical water reduction

This paper reports on the synthesis of reduced graphene oxide (RGO)-intercataled graphene oxide (GO) nano-hybrid and investigates its application in photoelectrochemical (PEC) water reduction. The optical, structural, and morphological properties of RGO-intercalated GO (RGO/GO) nano-hybrid were studied using UV–Visible spectroscopy, X-ray diffraction, and scanning electron microscopy, respectively. The reduction of GO to RGO was studied using FTIR spectroscopy. The XRD and FTIR investigation shows the strong π–π stacking interactions between the layered GO host–RGO guest sheets. An improvement in PEC water reduction activity was exhibited by RGO/GO nano-hybrid photoelectrode, with a maximum photocurrent of − 61.35 μA/cm2 for RGO 1 wt% in GO versus − 42.80 μA/cm2 for pristine GO photoelectrode (43% improvement). The mechanism for photocurrent enhancement was studied by electrochemical impedance analysis. The PEC performance enhancement of RGO/RO nano-hybrid photoelectrode is attributed to the strong π–π stacking interactions between RGO and GO, leading to superior electron collection and transportation by RGO and hence reduced charge carrier recombination. In addition, the UV–Visible absorption and Taut plot analysis showed the higher light harvesting efficiency of the RGO/GO compared to GO, displaying a band gap of 2.58 eV and 3.11 eV for RGO/GO and GO, respectively. The findings of this work show the potential of a strongly coupled layered host–guest nano-hybrids for high-performance optoelectronic materials.Graphic abstract

Effect of Fe3O4‐Decorated N‐Doped Reduced Graphene Oxide Nanohybrid on the Anticorrosion Performance of Epoxy Composite Coating

AbstractThe present study explores the synergistic effect of Fe3O4 and heteroatom doped reduced graphene oxide (rGO) nanohybrid on anti‐corrosion performance of epoxy composite coating. In this connection, Fe3O4 nanoparticles were decorated over nitrogen doped rGO (Fe3O4‐NRG) and characterized by Fourier transform infrared spectroscopy (FT‐IR), Raman spectroscopy, X‐ray diffraction (XRD), X‐ray Photoelectron spectroscopy (XPS), and Thermogravimetric analysis (TGA). This approach to modulating the surface properties of graphene and hence the interaction with polymer matrix were quite distinct from traditional surface functionlization or decoration in a sense that the doped nitrogen atom facilitate the growth of Fe3O4 particles and at the same time augmented the interaction of rGO with polymer matrix. The prepared nanohybrid was dispersed in epoxy matrix through mechanical mixing and coated over mild steel surface via spin coating technique. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) study revealed superior anti‐corrosion performance of Fe3O4‐NRG/epoxy coating in 3.5 wt% NaCl solution. The corrosion inhibition was found to improve by ∼ 98.5% with 0.5 wt% loading of Fe3O4‐NRG. We believe that this simple solvent free approach to prepare composite coating can be exploit for practical application and thus deserves special attention..

Riboflavin-Immobilized CeO2–RGO Nanohybrid as a Potential Photoredox Catalyst for Enhanced Removal of Organic Pollutants under Visible Light

We report a facile immobilization of riboflavin (RF) over in situ synthesized CeO2–reduced graphene oxide (RGO) nanohybrid surface synthesized through a simple wet-chemical approach for photocatalytic degradation of organic pollutants under visible light (λ ≥ 420 nm). The hybrid containing 3% w/w RGO shows an excellent photocatalytic activity under visible light. The UV–visible diffuse reflectance spectra, photoluminescence (PL) analysis, and transient photocurrent measurements corroborate that the hybrid RF@CeO2–RGO significantly absorbs visible light and exhibits lower recombination of charge carriers in comparison to RF@CeO2. The catalyst, RF@CeO2–RGO, offers enhancement in photocatalytic rate, i.e., 2.8-fold increase for methyl orange (MO) and 3.5-fold for p-nitrotoluene (PNT) in comparison to RF@CeO2 under visible light (2 h). This enhancement could be attributed to the synergistic effect among CeO2, RF (broadens visible light absorption region), and RGO (an electron-shuttling agent), which lead to a...