Surface Of rGO Nanosheets Research Articles

Selectively electrolyzing CO2 to ethylene by a Cu-Cu2O/rGO catalyst derived from copper hydroxide nanostrands/graphene oxide nanosheets.

Electrolyzing CO2 into ethylene (C2H4) is a promising strategy for CO2 utilization and carbon neutrality since C2H4 is an important industrial feedstock. However, selectively converting CO2 into C2H4 via the CO2 electro-reduction reaction (CO2 ERR) is still a great challenge. Herein, Cu-Cu2O nanoparticles anchored on reduced graphene oxide nanosheets (Cu-Cu2O/rGO) were prepared from copper hydroxide nanostrands (CHNs) and graphene oxide (GO) nanosheets via in situ electrochemical reduction. Cu-Cu2O nanoparticles with diameter less than 10 nm were formed on the surface of rGO nanosheets. After assembling the Cu-Cu2O/rGO catalyst into a flow cell, it demonstrated high Faraday efficiencies (FEs) of 55.4%, 37.6%, and 6.7% for C2H4, C2H6, and H2, respectively, and a total 93% FE for C2 at -1.3 V vs. the standard hydrogen electrode (SHE). Moreover, its FE was 68.2% for C2H4, 10.2% for C2H6, and 20.5% for H2 at -1.4 (vs. SHE). Besides, no liquid carbon product was detected. This high selectivity is attributed to the synergistic effect arising from the small diameter of Cu-Cu2O NPs with the combination of Cu0-Cu+ and rGO nanosheets, which promotes the activation of CO2 molecules, facilitates C-C coupling, and enhances stability. This may provide a facile way for designing an efficient catalyst for selectively electrolyzing CO2 into valuable C2 chemicals.

Visible Light-Triggered Catalytic Performance of Reduced Graphene Oxide Decorated With Copper Oxide Nanocomposite for Degradation of Rhodamine B Dye and Kinetics Studies.

Herein, novel nanocomposites based on reduced graphene oxide decorated copper oxide nanoparticles (rGO/CuO) were prepared by the in situ co-precipitation method. The structural, morphological, and optical characterization of as-prepared nanocomposites was performed by powdered x-ray diffraction (p-XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR), Raman, and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The as-prepared nanocomposites exhibited better photocatalytic activity of rhodamine B dye with maximum ~94% degradation in 120 min with a rate constant of 0.2353 min-1 under optimized conditions. Furthermore, the effects of solution pH and catalyst loading are studied on the degradation process. Therefore, this state-of-the-art strategy for the decoration of CuO nanoparticles onto the surface of rGO nanosheets could be an ideal platform for fabricating highly efficient photocatalysts.

Non-covalent functionalization of surfactant-assisted graphene oxide with silver nanocomposites for highly efficient photocatalysis and anti-biofilm applications

This study presents a comprehensive investigation on the synthesis and characterization of surfactant-assisted graphene oxide non-covalent functionalized silver nanocomposites (rGS-AgNPs) for achieving remarkable photocatalytic and anti-biofilm properties. The approach involves using an anionic surfactant (sodium lauryl sulfate (SLS)), silver nitrate (AgNO3), and reduced graphene oxide (rGO) as stabilizing/reducing agents, metal precursors, and supporting materials, respectively. Different composites were prepared by varying the concentration of AgNO3, resulting in rGS-AgNPs composites with concentrations of 0.9 × 10−3 mM, 1.8 × 10−3 mM, and 2.7 × 10−3 mM. Characterization techniques including XRD, FTIR, SEM, and TEM/EDS analysis confirmed the formation of face-centered cubic AgNPs and amorphous rGO structures. The composites exhibited a firm binding of the surfactant and AgNPs on the surface of rGO nanosheets, resulting in efficient anti-biofilm and photocatalytic activity. The size of the supported AgNPs on rGO/SL was found to be 8–10 nm. The rGS-AgNPs composites displayed significantly improved anti-biofilm and photocatalytic performance, attributed to the increased surface area of AgNPs. Moreover, the photocatalytic efficiency of the rGS-AgNPs composites reached 96.48 % within 60 min, outperforming pure AgNPs. The synthetic producre and practical applications will be utilized for biosensors, food packing technology, biomedical and pharmaceutically valuable reactions.

Engineering 2D/2D oxygen vacancy-rich CoAl LDH/rGO sheet-on-sheet heterostructures with improved charge storage for supercapacitors

Layered double hydroxides (LDHs) as electrode materials for supercapacitors still suffer from limited actual specific capacities and unsatisfactory cycling performance owing to their poor intrinsic electrical conductivity and insufficient electroactive sites. Herein, oxygen vacancy (Ov)-rich CoAl-LDH nanosheets are attached onto reduced graphene oxide (rGO) nanosheets to form 2D/2D Ov-CoAl-LDH/rGO sheet-on-sheet heterostructures via a facile precipitation-reduction reaction followed by hydrothermal treatment. The introduction of rich Ov defects in CoAl-LDHs enhances the electrical conductivity, while the attachment of Ov-CoAl-LDH nanosheets on the surface of rGO nanosheets not only reduces the aggregation of Ov-CoAl-LDH nanosheets and thus exposes abundant electroactive sites, but also maintains good structural stability. Theory calculations indicate that the Fermi-level difference of two components triggers interfacial charge separation while creating a built-in electric field at the Ov-CoAl-LDH/rGO interface, which favors rapid electron/ion migration and accelerates charge storage kinetics. The optimized Ov-CoAl-LDH/rGO nanocomposites deliver specific capacities of 984 C g−1 at 3 A g−1 and 708 C g−1 at 20 A g−1 and retain an initial capacity of 90 % after 10,000 cycles at 10 A g−1. These findings showcase a feasible strategy to endow 2D/2D LDHs/graphene heterostructures with enhanced charge storage performance.

(Invited) Reduced Graphene Oxide Complexed to MnO2 Nanoparticles as Efficient Platform for Photothermal and Chemodynamic Combined Therapy

The intracellular cascade reactions triggered by nanomateraials are emerging as promising strategies to treat cancer more efficiently, by exploting the specific tumour microenvironment [1]. One of the mechanisms of cell ablation is based on depletion of glutathione (GSH) and generation of reactive oxygen species (ROS). We recently exploited reduced graphene oxide (rGO), one of the most popular form of graphene, in combination with manganese dioxide nanoparticles (MnO2 NPs) to design a multifunctional nanoplatform (rGO@MnO2) for efficient photothermal/chemodynamic combined therapies. Manganese-based NPs were bound onto the surface of rGO nanosheets (rGO NSs). These NPs are able to oxidize intracellular GSH, generating Mn2+ ions that convert H2O2 into hydroxyl radicals by Fenton reaction. In addition, rGO NSs mediated photothermal therapy (PTT) enhance the mortality of cancer cells. The high temperature caused by photothermal conversion increases the Fenton reaction rate, which enhances the efficiency of MnO2 NPs mediated chemodynamic therapy (CDT). Such type of hybrid materials has great potential in cancer therapy by exploiting the synergistic effect of PTT and CDT.[1] Ma, B.; Guo, S.; Nishina, Y.; Bianco, A. Reaction between Graphene Oxide and Intracellular Glutathione Affects Cell Viability and Proliferation. ACS Appl. Mater. Interfaces 2021, 13, 3528-3535. DOI:10.1021/acsami.0c17523[2] Ma, B.; Nishina, Y.; Bianco, A. A glutathione responsive nanoplatform made of reduced graphene oxide and MnO2 nanoparticles for photothermal and chemodynamic combined therapy. Carbon 2021, 178, 783-791. DOI:10.1016/j.carbon.2021.03.065

RGO-WO3 Heterostructure: Synthesis, Characterization and Utilization as an Efficient Adsorbent for the Removal of Fluoroquinolone Antibiotic Levofloxacin in an Aqueous Phase.

Herein, the heterostructure rGO-WO3 was hydrothermally synthesized and characterized by HRTEM (high-resolution transmission electron microscopy), FESEM (field emission scanning electron microscopy), XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron microscopy), nitrogen physisorption isotherm, Raman, TGA (thermogravimetric analysis) and zeta potential techniques. The HRTEM and FESEM images of the synthesized nanostructure revealed the successful loading of WO3 nanorods on the surface of rGO nanosheets. The prepared heterostructure was utilized as an efficient adsorbent for the removal of a third-generation fluoroquinolone antibiotic, i.e., levofloxacin (LVX), from water. The adsorption equilibrium data were appropriately described by a Langmuir isotherm model. The prepared rGO-WO3 heterostructure exhibited a Langmuir adsorption capacity of 73.05 mg/g. The kinetics of LVX adsorption followed a pseudo-second-order kinetic model. The adsorption of LVX onto the rGO-WO3 heterostructure was spontaneous and exothermic in nature. Electrostatic interactions were found to have played a significant role in the adsorption of LVX onto the rGO-WO3 heterostructure. Thus, the prepared rGO-WO3 heterostructure is a highly promising material for the removal of emerging contaminants from aqueous solution.

Iron carbide-nitride supported at the surface of rGO towards enhancing the thermal decomposition of energetic molecular perovskite

In this paper, we investigated the effect of Iron carbide-nitride/reduced graphene oxide composites (FeCxNy/rGO) as catalysts on the thermal decomposition of energetic molecular perovskite (H2dabco)[M(ClO4)3] (DAPs, M = Na+, K+ and NH4+ for DAP-1, -2, and -4). FeCxNy/rGO were fabricated by two-step method combined with chemical synthesis and sinter technology of Prussian blue/reduced graphene oxide (PB/rGO). The morphology and structure of FeCxNy/rGO were characterized. The thermal decomposition performance of DAPs with FeCxNy/rGO catalyzed were studied. Results showed that FeCxNy particles with mainly Fe–C and Fe–N bonds involved were located at the surface of rGO nanosheets, the peak thermal decomposition temperature and the apparent activation energy of DAPs were both significantly decreased in the presence of FeCxNy/rGO. Among them, with 5 wt% FeCxNy/rGO-2 added, the peak temperature of DAP-1, DAP-2, and DAP-4 have been decreased by 104.8 °C, 110 °C and 102.2 °C, respectively. Their apparent activation energy decreased significantly by 4.0 kJ/mol, 74.9 kJ/mol and 66.9 kJ/mol, respectively. A possibly thermal catalysis decomposition mechanism was provided. This work provides a new idea for design and fabrication of multifunctional catalysts to enhance the thermal decomposition of energetic molecular perovskite and offers the possibility of applying DAPs to rocket solid propellant.

Electrochemical Alcohol Oxidation and Biological Properties of Mn3O4-Co3O4-rGO

A multi-component nanocomposite consisting of manganese oxide (Mn3O4), cobalt oxide (Co3O4), and reduced graphene oxide (rGO) in the form of Mn3O4-Co3O4-rGO was synthesized by the hydrothermal method. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) analyses were performed to investigate the synergistic effect of metal oxides on the surface of rGO nano-sheets in the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR) process. The good electrochemical results show that Mn3O4-Co3O4-rGO can be a promising, inexpensive nano-catalyst for application in alcohol fuel cells. In addition, as nanoparticles inhibit cancer cell growth by producing reactive oxygen species (ROS), we explored the synergic effect of the three-component synthetic nanomaterial in gastric cancer cells (AGS). Results indicated that Mn3O4-Co3O4-rGO inhibited AGS cell growth by induction of ROS, upregulation of Mir-20a-5p, and downregulation of ZBTB4 gene. This might provide a novel molecular-targeted strategy of microRNA-based therapeutics for gastric cancer treatment.

Crinkly Polypyrrole-Modified reduced graphene oxide loaded Pd nanoparticles as Highly efficient electrocatalyst for ethylene glycol oxidation

Exploration of suitable support materials for noble metal nanocatalysts to reduce the mass loading and optimize the electrocatalytic performance for ethylene glycol oxidation reaction (EGOR) remains a key challenge. Herein the crinkly polypyrrole (PPy)-modified reduced graphene oxide (rGO) was prepared through a facile and efficient in-situ polymerization approach and utilized as the support for Pd nanoparticles. PPy as “spacers” coating on the surface of rGO nanosheets, inhibiting the aggregation and restacking, which greatly increased the available surface area of rGO. Furthermore, this interface-rich structure can offer an efficient pathway for electron conduction, which helps to improve the electrochemical properties of the catalyst. More impressively, the optimized Pd-PPy-rGO1 nanocomposite outperforms the Pd-PPy and commercial Pd-C with the higher mass activity/specific activity (5550.2 mA mgPd-1/30.0 mA cm−2), the improved intrinsic activity (TOF value of 6.5 s−1) and the enhanced stability toward electrocatalytic EGOR. The superior electrocatalytic performance benefits from the increased specific surface area of the crinkly and interface-rich PPy-rGO and the high utilization efficiency of Pd active sites during the EGOR. This work is expected to give a rational avenue to design interface-rich conducting polymer-rGO nanocomposite support for fuel cells anode catalysts.

ZrO2-anchored rGO nanohybrid for simultaneously enhancing the wear resistance and anticorrosion performance of multifunctional epoxy coatings

ZrO2 nanoparticles were controllably anchored on the surface of rGO nanosheets via an environmentally friendly single-step hydrothermal reaction and then incorporated into epoxy coatings to simultaneously improve the wear resistance and anticorrosion performance of the coatings. Based on the structural characterization and analysis, ZrO2 nanoparticles were homogeneously anchored on the surface of rGO through the charge attraction between GO and the Zr(IV) complex ions in the precursor. The addition of 0.5 wt% ZrO2@rGO nanohybrids to the epoxy resin coating (ZrO2@rGO/EP) significantly improved the adhesion strength, impact resistance and surface hardness. Tribological investigation revealed that the average friction coefficient of ZrO2@rGO/EP decreased by 41.96% and the wear resistance improved by 57.69%. Characterization of the worn surface indicated that the main wear mechanism of ZrO2@rGO/EP was abrasive wear with smooth and slightly damaged surface morphology. The anti-wear improvement is attributed to the filling effect of small wear debris of ZrO2@rGO/EP on the groove and the loading effect of hard ZrO2@rGO nanohybrid debris. SEM images and EDS line scan of worn surfaces of the friction counterparts confirmed the friction transfer effect of ZrO2@rGO/EP. After the ZrO2@GO/EP was soaked in 3.5 wt% NaCl solution for 7 days, the impedance modulus reached 2.50 × 106 Ωcm2, one order of magnitude higher than that of pure EP. The phase angle (105 Hz) was close to 90°, almost twice that of pure EP. The Rc value fitted via Zview software was two orders of magnitude higher. Electrical equivalent circuit models indicated the enhanced anti-corrosion performance. The as-prepared ZrO2@rGO hybrid in EP coatings could effectively prevent electrolyte penetration, and ZrO2 nanoparticles played a synergistic role with rGO nanosheets in alleviating corrosion. It provides a controllable and effective strategy for developing multifunctional ceramic/graphene/organic coatings with enhanced wear resistance and anti-corrosion performance.

Construction of rGO-SnO2 heterojunction for enhanced hydrogen detection

Sandwich-structured rGO-SnO2 nanocomposites comprising of reduced graphene oxide (rGO) nanosheets and SnO2 nanoparticles were prepared by a simple refluxing reaction, and its hydrogen sensing performance was investigated. The structural characterization confirmed that the ultra-fine cylindrical SnO2 nanoparticles with length of ∼ 15 nm and diameter of ∼ 5 nm were loaded on the surface of rGO nanosheets. BET surface area of rGO-SnO2 nanocomposite enhanced as the amount of GO increased. Additionally, the increase in the amount of GO effectively inhibited the disproportionation reaction of Sn2+ during the annealing process. When the mass ratio of GO to SnO2 was higher than 1.0 wt%, the disproportionation reaction of Sn2+ was completely suppressed and all Sn-related products were changed into SnO2 phases. The 1.0 wt% rGO-SnO2 nanocomposites based gas sensor showed the highest response of 11.88 to 500 ppm H2 at 225 °C, with fast response/recovery times of 2 s/19 s and a detection limit of lower than 5 ppm. Especially, the sensor showed good reproducibility, selectivity, moisture resistance, and long-term stability. H2 sensing mechanisms of rGO-SnO2 nanocomposites were discussed based on the experimental data and gas-sensing reaction theory.

Design and Fabrication of High Performance Photoanode of Fe2(MoO4)3/RGO Hybrid Composites for Triiodide Reduction in Dye-Sensitized Solar Cells

Here in, synthesis of Fe2(MoO4)3/reduced graphene oxide (RGO) nanocomposite was prepared by simple hydrothermal approach and used as high efficient dye sensitized solar cells (DSSCs). The decoration of RGO into the Fe2(MoO4)3 was proved by various physic-chemical studies such as XRD, SEM, TEM, Raman, UV, PL and BET analysis. The individual spherical shaped nanoparticles of Fe2(MoO4)3 with sizes in the range of 25–35 nm was uniformly decorated on the surface of RGO nanosheets. Due to the synergic effect between the Fe2(MoO4)3 and RGO the light absorption property is significantly improved as well the high surface area (112.5 m2/g) and pore size (38.7 nm) was achieved than compared with bare Fe2(MoO4)3 (88.5 m2/g and 17.8 nm). The Fe2(MoO4)3/RGO hybrid photoanode establish to display an outstanding catalytic activity toward the reduction of triiodide to iodide in a dye-sensitized solar cell (DSSC) and can provide a solar cell efficiency of 9.6 ± 0.001%, which is superior to a Pt-based DSSC (6.1 ± 0.002%). The better electro-catalytic ability of Fe2(MoO4)3/RGO electrode is obtained by a synergistic effect that resulted in the high specific surface area and intrinsic reactivity of the materials.

Construction of a sensitive electrochemical sensor based on hybrid 1 T/2H MoS2 nanoflowers anchoring on rGO nanosheets for the voltammetric determination of acetaminophen

In this work, an ultrasensitive electrochemical sensor towards quantitative detection of acetaminophen (AP) based on hybrid of metallic 1 T and semiconductive 2H phase molybdenum disulfide (1 T/2H MoS2) anchored on rGO sensing platform was constructed. The XRD, FESEM, FETEM and XPS analysis indicates that nanoflowers 1 T/2H MoS2 with walnut-like fold structure were in-situ loaded onto the surface of rGO nanosheets by the hydrothermal approach. The formation of stabilized 1 T MoS2 is associated with the influence of GO. The electrochemical tests of CV, EIS and DPV show that the hybrid composite MoS2/rGO remarkably promoted the detecting performance owing to the increased conductivity of 1 T MoS2 that can facilitate charge transfer kinetics, the great active sites on both basal and edge of planes of 1 T/2H MoS2 and the synergic effect of 1 T/2H MoS2 and rGO. After the test condition optimization, MoS2/rGO/GCE sensor has great electrocatalytic activity towards AP with wide linear range of 0.005–300 μM and low limit of detection of 1.7 nM (S/N = 3). Furthermore, the sensor shows excellent stability, repeatability, reproducibility and anti-interference performance. All results proved that the GO-assisted hydrothermal prepared hybrid 1 T/2H MoS2/rGO is promising material for electrochemical analysis.

Improved dielectric properties of PVDF polymer composites filled with Ag nanomaterial deposited reduced graphene oxide (rGO) hybrid particles

We report a method to improve the dielectric constant (ε′) of polyvinylidene fluoride (PVDF) composites by using a low content of Ag nanomaterials deposited reduced Graphene Oxide (rGO) Hybrid Particles (Ag-rGO HPs). The Ag-rGO HPs are prepared by a reaction between silver nitrate and ethylene glycol in a seed-mediated growing process. The dispersion of Ag nanomaterials was completely homogeneous on the surface of rGO nanosheets with particle sizes of 5.765 ± 0.189 nm. The Ag-rGO HPs/PVDF composites were produced by a liquid–phase assisted dispersion and hot-pressing methods. The high ε′ at 103 Hz for Ag-rGO/PVDF composites with fAg-rGO 7.8, and 11.9 vol% was 153 and 683, respectively. The best-fitting curve was completely achieved in percolation theory by adjusting fc = 14 vol%. The high ε′ (683 at 1 kHz) of Ag-rGO/PVDF could be explained by Maxwell Wagnare Sillars interfacial polarization and micro-capacitor due to the formation of a sandwich between Ag-rGO and PVDF.

A glutathione responsive nanoplatform made of reduced graphene oxide and MnO2 nanoparticles for photothermal and chemodynamic combined therapy

Based on the specific tumor microenvironment, characterized by an overproduction of H2O2 and a high glutathione (GSH) concentration, the cascade reactions of nanomaterials, capable of mediating GSH depletion and reactive oxygen species (ROS) generation, have become a popular strategy to increase cancer therapy efficiency. In this study, we exploited reduced graphene oxide (rGO), one of the most promising graphene-based materials, in combination with manganese dioxide nanoparticles (MnO2 NPs) to design a multifunctional nanoplatform (rGO@MnO2) for efficient photothermal/chemodynamic combined therapies. MnO2 NPs were anchored onto the surface of rGO nanosheets (rGO NSs). MnO2 NPs oxidize intracellular GSH, and the generated Mn2+ ions converted H2O2 into HO by Fenton reaction. Meanwhile, rGO NSs mediated photothermal therapy (PTT) could further kill cancer cells. High temperature caused by photothermal conversion increased Fenton reaction rate, which enhanced the efficiency of MnO2 NPs mediated chemodynamic therapy (CDT). Importantly, thanks to the enhanced cell uptake of MnO2 NPs favored by the delivery properties of rGO, rGO@MnO2 possessed higher lethality to cancer cells. The decrease in the nanomaterials’ effective dose would further improve biosecurity and reduce cost. Therefore, rGO@MnO2 have great potential in cancer therapy by exploiting the synergistic effect of PTT and photothermal/delivery effect enhanced CDT.

Hybrid two-dimensional nickel oxide-reduced graphene oxide nanosheets for supercapacitor electrodes

The graphene oxide (GO) nanosheets as well as the two-dimensional Ni(OH)2 with excellent uniformity were prepared with a hydrothermal and Hummers method, respectively. Ni(OH)2 nanosheets treated by cationic surfactants and graphene oxide with negative charges were mixed by electrostatic self-assembly. After annealing, hybrid two-dimensional NiO-reduced graphene oxide nanosheets (NiO-rGO) were obtained. Attributing to the synergistic effects, the NiO-rGO electrode exhibits an optimized electrochemical performance, in contrast to pure NiO or rGO supercapacitor. The results show the NiO nanosheets are homogeneously dispersed on the surface of rGO nanosheets and the hybrid NiO-rGO nanosheets electrode can deliver an excellent capacity of 343 C·g−1 (1 A·g−1). Furthermore, the electrodes made up of NiO-rGO nanosheets are employed to assemble symmetric supercapacitor. The energy density of as-prepared supercapacitor device can reach up to 5.4 Wh·kg−1 at a power density of 0.43 kW·kg−1 operated in the voltage range of 0–1.4 V. In addition, the symmetric supercapacitor also exhibits an excellent capacitance retention of 90% after 10,000 cycles (10 A·g−1).

Ru x Pd y Alloy Nanoparticles Uniformly Anchored on Reduced Graphene Oxide Nanosheets (Ru x Pd y @rGO): A Recyclable Catalyst.

In this work, RuxPdy alloy nanoparticles were uniformly decorated on a two-dimensional reduced graphene oxide (rGO) sheet by an in situ chemical co-reduction process. The resulting products were characterized by various physiochemical techniques such as X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic absorption spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Further, the synthesized RuxPdy@rGO nanocomposites have been employed as a heterogeneous catalyst for three different catalytic reactions: (1) dehydrogenation of aqueous ammonia borane (AB); (2) hydrogenation of aromatic nitro compounds using ammonia borane as the hydrogen source, and (3) for the synthesis of aromatic azo derivatives. The present work illustrates the sustainable anchoring of metal nanoparticles over the surface of rGO nanosheets, which could be used for multifarious catalytic reactions.

Fabrication of hierarchical 3D prickly ball-like Co–La oxides/reduced graphene oxide composite for electrochemical sensing of l-cysteine

A novel 3D prickly ball-like Co–La oxides/reduced graphene oxide composite (Co–La oxides/rGO) has been successfully synthesized by a facile thermal evaporation method. Co–La oxides were hierarchical spiny globular structure made up of numerous radially-grown nanowires with the size of about 50 nm in width. Some of the nanowires grow vertically on the surface of rGO nanosheets. GO was thermally reduced to rGO. XPS data showed that the Co3+, Co2+ and La3+ existed in the prepared samples. The possible growth mechanism was tentatively proposed. The application of the 3D prickly ball-like Co–La oxides/rGO as electrode-modified material for electrochemical oxidation of l-cysteine was studied. The prepared prickly ball-like Co–La oxides/rGO modified electrode expressed prominent electrocatalytic ability for the electrochemical oxidation of l-cysteine. Under optimum experimental conditions, the current response of l-cysteine were linear with its concentration in the range of 1.0–888.0 μM with a low detection limit of 0.1 μM (S/N = 3). The sensor was used to evaluate its application for the detection of l-cysteine in the real samples.

Strategic design of Cu/TiO2-based photoanode and rGO-Fe3O4-based counter electrode for optimized plasmonic dye-sensitized solar cells

Abstract The current research work demonstrates the modification of both functional electrodes of a plasmonic dye-sensitized solar cell (PDSSC) to fabricate a low-cost and efficient solar device. The copper-doped titania (Cu/TiO2) nanocomposite and hybrid magnetite nanoparticles decorated reduce graphene oxide (rGO/Fe3O4) nanocomposite were produced by a facile single step wet synthesis approach by utilizing non-toxic and cost-efficacious precursors. The as-synthesized nanocomposites were comprehensively analyzed by using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, thermogravimetric analysis and UV–Vis spectroscopic techniques to evidently confirm the formation of Cu/TiO2 and hybrid rGO/Fe3O4 nanocomposites successfully. The photovoltaic parameters of the PDSSCs were investigated by measuring J-V characteristics and IPCE spectra. The Cu/TiO2 nanocomposite based photoanode demonstrated power conversion efficiency (PCE) of 3.89% with platinum (Pt) and 2.20% with hybrid rGO/Fe3O4 counter electrodes (CEs) respectively in PDSSCs. The hybrid rGO/Fe3O4 CE based PDSSC approached to 57% of the efficiency of the traditional platinum electrode with Cu/TiO2 and 70% with that of pristine TiO2 based photoanodes. The reasonable enhancement in efficiency might be ascribed to uniform dispersion of catalytic Fe3O4 nanoparticles on the surface of rGO nanosheets and due to plasmonic effect of Cu nanoparticles. The results suggested that the synergistic combination of modified functional electrodes in plasmonic DSSCs exhibited a reasonable efficiency and thus could prove to be as an effective substituent of traditional and expensive Pt.

CdSe- Reduced graphene oxide nanocomposite toxicity alleviation via V2O5 shell formation over CdSe core: in vivo and in vitro studies

The present article demonstrates the synthesis of the nanocomposite of reduced graphene oxide (rGO) with CdSe and CdSe/V2O5 core/shell quantum dots by a two-step facile synthesis approach and subsequently studies their relative biocompatibility in different cells. Various characterization techniques have been applied including transmission electron microscopy (TEM), an x-ray diffractometer (XRD) and Raman spectroscopy to confirm the successful formation of CdSe-rGO and CdSe/V2O5-rGO nanocomposites. The average sizes of CdSe and CdSe/V2O5 QDs have found to be ∼3 and 5.5 nm, respectively with a good dispersion over the surface of rGO nanosheets. A crystal phase change has occurred during the formation of the V2O5 shell over the surface of CdSe QDs and confirmed through XRD. Raman spectroscopy has shown some useful insight of the surface state of CdSe and consequent changes in the surface with V2O5 shell growth.Further, MTT and cell growth assays have been performed to analyze their biocompatibility in A549 and Hela cells with various concentrations of as-synthesized materials. Our results demonstrate the toxicity of CdSe-rGO nanocomposite to be substantially reduced by the growth of the V2O5 shell. The in vivo studies in Drosophila show a remarkable decrease in the reactive oxygen species (ROS) and apoptosis levels for a CdSe/V2O5-rGO composite as compared to a CdSe-rGO nanocomposite, which paves a promising pathway for the CdSe/V2O5-rGO nanocomposite to be used as an efficient biocompatible material.