Reduced Graphene Oxide Nanosheets Research Articles

Amorphous lithiophilic cobalt‐boride@rGO interlayer for dendrite‐free and highly stable lithium metal batteries

AbstractLithium metal batteries (LMBs) are recognized to be crucial for secondary battery technology targeting electric vehicles and portable electronic devices. However, the undesirable growth of lithium dendrites would result in reduced capacity, short‐circuit, and overheating, seriously hindering the practical applications of LMBs. To address this issue, a neoteric lithiophilic interlayer on a commercial polypropylene separator is presented for the first time, which is constructed by amorphous CoB nanoparticles decorated reduced graphene oxide nanosheets (CoB@rGO). Density Functional Theory calculations and experimental analysis reveal remarkable lithiophilicity features for CoB@rGO and provide multiple Li deposition sites and improved electrolyte wettability, which facilitates the formation of durable solid electrolyte interphase (SEI), reduces side reactions, and improves Li+ flux regulation for long‐term cycling stability in LMBs. Taking advantage of these merits, the symmetric Li//Li cell with CoB@rGO/PP separator exhibits stable cycling for up to 1600 h at 1 mA cm−2 with 1 mAh cm−2. Employed with CoB@rGO separator, the Li//LiFePO4 full cell with a high LiFePO4 loading of 11 mg cm−2 delivers a high initial specific capacity of 115.3 mAh g−1 and a low decay rate of 0.08% per cycle after 200 cycles even at a high rate of 2C.

RGOs-AgNPs/PVA composite sponges for efficient solar saltwater evaporation

With an increasing demand for seawater desalination, fabricating photothermal materials with low cost, high photothermal conversion efficiency, and excellent mechanical stability is necessary but remains challenging. In this work, reduced graphene oxide nanosheets (RGOs) and silver nanoparticles (AgNPs) doped polyvinyl alcohol (PVA) sponges (RGOs-AgNPs/PVA) are fabricated by the mechanical foaming and impregnation reduction method, which combine the flexible porous structure of PVA sponges with the photothermal properties of RGOs-AgNPs. The incorporation of RGOs-AgNPs enhances the surficial hydrophobicity and reduces the accumulation of water on the surface, and the photothermal synergistic effect of RGOs-AgNPs enhances the water evaporation rate. The results showed that the evaporation rate of RGOs-AgNPs/PVA was 2.09 kg m−2 h−1 and the photothermal conversion efficiency was 94.2 % under standard sunlight intensity of 1 sun (1.0 kW m−2). Furthermore, the long-term stability and effective desalination capability of the RGOs-AgNPs/PVA solar evaporation device offer a potential opportunity for massive seawater desalination. Therefore, this work shows the prospect of combining flexible porous sponges with photothermal materials for practical solar evaporation.

Biologically templated formation of Cobalt-Phosphide-Graphene hybrids with charge redistribution for efficient hydrogen evolution

Developing highly efficient and sustainable hydrogen evolution reaction (HER) electrocatalysts is important for the practical application of emerging energy technologies. The spherical structure and phosphorus-rich properties of Chlorella can facilitate the construction of comparable transition metal phosphide electrocatalysts. Here, a microorganism template strategy is proposed to construct a cobalt-phosphide-graphene hybrid. Chlorella can absorb metal ions, and the generated rough spherical nanoparticles are uniformly distributed around the reduced graphene oxide nanosheets. This designed catalyst has comparable HER performance in acidic electrolytes and needs an overpotential of only 153 mV at a current density of 10 mA cm−2. The experimental and density functional theory results imply that the charge redistribution between Co2P and pyrrole-N is the key factor in enhancing the HER activity. The induced electron aggregation at the N and P sites can serve as a key active site for absorbing the adsorbed hydrogen atom intermediate to accelerate the HER process, contributing to the active sites of Co2P- and pyrrole-N-doped carbon with 0 eV hydrogen adsorption free energy. This work provides a broad idea for synthesizing advanced catalysts by a biological template approach, facilitating the innovative integration of biology and emerging electrochemical energy technologies.

Graphene nanosheet reinforcement of polyurethane nanocomposite for green and sustainable photoluminescence, superhydrophobic, and anticorrosive paint.

A simple and environmentally friendly method was developed for smart and efficient waterborne polyurethane (PUR) paint. Sugarcane bagasse was recycled into reduced graphene oxide nanosheets (rGONSs). Both lanthanide-doped aluminate nanoparticles (LAN; photoluminescent agent, 7-9nm) and rGONSs (reinforcement agent) were integrated into a waterborne polyurethane to produce a novel photoluminescent, hydrophobic, and anticorrosive nanocomposite coating. Using ferrocene-based oxidation under masked circumstances, graphene oxide nanosheets were produced from sugarcane bagasse. The oxidized semicarbazide (SCB) nanostructures were integrated into polyurethane coatings as a drying, anticorrosion, and crosslinking agent. Polyurethane coatings with varying amounts of phosphor pigment were prepared and subsequently applied to mild steel. The produced paints (LAN/rGONSs@PUR) were tested for their hydrophobicity, hardness, and scratch resistance. Commission Internationale de l'éclairage (CIE) Laboratory parameters and photoluminescence analysis established the opacity and colourimetric properties of the nanocomposite coatings. When excited at 365 nm, the luminescent transparent paints emitted a strong greenish light at 517 nm. The anticorrosion characteristics of the coated steel were investigated. The phosphor-containing (11% w/w) polyurethane coatings displayed the most pronounced anticorrosion capability and long-persistent luminosity. The prepared waterborne polyurethane paints were very photostable and durable.

Augmenting Piezoelectric Performance of Poly (vinylidene fluoride) Nanogenerator with Zinc Oxide Nanorods Decorated Reduced Graphene Oxide Nanosheets

Augmenting Piezoelectric Performance of Poly (vinylidene fluoride) Nanogenerator with Zinc Oxide Nanorods Decorated Reduced Graphene Oxide Nanosheets

Engineering of 3D architectures with yttrium on reduced-graphene oxide nanosheets for effective co-adsorption of tetracycline and phosphate

Effective removal of composite pollutants containing antibiotic and phosphorus is still facing challenges for the wastewater treatment. In this study, yttrium-hydroxide component was loaded onto the surface of reduced GO nanosheets via low-temperature hydrothermal method, to synthesize the 3D YrGO architectures. The optimized YrGO-8 hydrogels showed the maximum adsorption capacity of 226.45 mg/g for tetracycline (TC), and 33.403 mg/g for phosphate, which was higher than many other reported adsorbents. The characterization results demonstrated that the rGO nanosheets were successfully crosslinked by Y(III) to form a porous 3D structure, which was beneficial to the mass transfer and active sites exposure. The adsorption behaviors of TC or phosphate was suppressed by the co-existing phosphate ions or TC, with slower adsorption rate and lower adsorption amount. Importantly, column adsorption analyzed by Thomas model illustrated the rate basis of YrGO-8beads to capture TC/phosphate in an adsorbate diffusion rate. Moreover, the 3D YrGO-8 remained stable and high reusability in multi-uptake-release rounds via pH regulation. The mechanism study suggested that the sequence of adsorption process of TC followed the order of hydrogen bond (HB) > π – π electron donor–acceptor (EDA), n − π EDA > Y(III) bridging interactions, while the uptake of phosphate formed Y-O-P inner-sphere complexes prior to HB. This study proposes a novel insight into the development of 3D architectures for effectively simultaneous treatment of composite TC and phosphate pollution.

Melt processing of graphene-coated polylactide granules for producing biodegradable nanocomposite with higher mechanical strength

ABSTRACT Innovative melt processing technology is necessary for the production of biodegradable polylactide/graphene nanocomposites. In this paper, we present the aqueous spray coating method to prepare graphene-coated polylactide granules for improving the distribution of small graphene contents in polymer matrix during the melt mixing process. Three types of functionalized graphene nanosheets, including graphene oxide (GO), reduced graphene oxide (RGO) and poly(ethylene glycol)/RGO (PEG/RGO), were investigated in the formations of graphene coatings on polylactide granules and subsequent melt-processed nanocomposites. It is found that RGO nanosheets have good interfacial compatibility to form better coatings on polylactide granules. Melt processing of graphene-coated granules produced polylactide/graphene nanocomposites with higher mechanical strengths. Nanocomposite materials containing 0.1% RGO showed the best improvements of mechanical and thermal properties. As-prepared nanomaterials and nanocomposites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), attenuated total reflectance infrared spectroscopy (ATR-FTIR), tensile, flexural and impact measurements, differential scanning calorimetry (DSC) and integrated thermogravimetric analysis (TGA-DTA). In general, the innovative strategy of aqueous spray coating and melt processing is applicable for manufacturing biodegradable PLA/graphene nanocomposites in the sustainable trend of environmentally friendly development.

Building ordered graphene membranes by intermediate layer assisted stacking method for promoted desalination

Laminar separation membranes stacked by graphene and its derivatives hold the merit of controlled mass transfer behaviors. However, precise ion separation is challenged by the disordered assembly of nanosheets on macroporous substrates with complicated surface properties. Herein, we prepare ultrathin ordered graphene membranes by an intermediate layer assisted stacking method. Nanoporous covalent organic framework (COF) nanosheets are first vacuum-filtered on macroporous substrates, followed by deposition and thermal reduction of graphene oxide nanosheets to deliver ultrathin reduced graphene oxide (rGO) layers. The COF-decorated substrates provide a hydrophilic surface with reduced pores and roughness, facilitating the formation of ultrathin rGO layers with ordered stacking patterns and reduced microporous defects. Consequently, the obtained rGO/COF composite membranes can reject ~90 % of Na2SO4, ~50 % of NaCl, and >98 % of various organic dyes, which are higher than pure rGO membranes. Meanwhile, the rGO/COF composite membranes can maintain good stability in solutions with different pH values and salt concentrations, and can be long-term operated for at least 10 days. This work is expected to deepen the understanding of the structure of laminar membranes and provides new perspectives to design ordered laminar membranes.

Synthesis, characterization, and FDTD simulations of Ag-enriched RGO nanosheets for catalytic reduction of 4-nitrophenol

Reduced graphene oxide-based nanocomposites are eminent materials having diverse applications including environmental remediation. The present work emphasizes the facile one-step co-reduction method for synthesizing silver nanoparticle (Ag NPs) decorated reduced graphene oxide (RGO) for catalytic reduction of 4-nitrophenol. FDTD simulation studies justify the experimental results, and XRD studies confirmed the reduction of graphene oxide and the formation of Ag NPs with reduced graphene oxide (AgRGO) composite. Raman analysis complements the structure, crystallinity, and defects in the fabricated material. XPS analysis verifies the reduction of graphene oxide (GO) into RGO and the decoration of metallic Ag on the surface of RGO. FESEM image showed the decoration of Ag NPs on the surface of RGO. AgRGO exhibited appreciable catalytic performance for reducing 4-nitrophenol in the presence of sodium borohydride compared to GO and RGO.

Simple solid-state synthesis of mesoporous NiCo2O4/N-doped reduced graphene oxide nanosheet composites with enhanced performance in electrochemical capacitors

Simple solid-state synthesis of mesoporous NiCo2O4/N-doped reduced graphene oxide nanosheet composites with enhanced performance in electrochemical capacitors

Synthesis of Ag @CuO nanocomposites supported by reduced graphene oxide nanosheets: harnessing photocatalytic degradation of naphthol blue black dye

The significance of utilizing photocatalysts to degrade toxic dyes and microbes has grown in recent years. It has been demonstrated as a successful method for utilizing light through hybrid photocatalysts to break down harmful organic molecules. This study aims to investigate the potential applications of CuO–Ag/rGO nanocomposites in environmental remediation. The nanocomposites were synthesized by incorporating Ag and CuO nanoparticles onto rGO nanosheets via hydrothermal method. The nanocomposites that resulted were thoroughly characterized using various analytical techniques to determine their chemical structure, morphology, crystallinity, and photocatalytic application. The degradation efficiency of naphthol black blue (NBB) dye under visible light irradiation was used to assess the photocatalytic performance of the nanocomposites. It was revealed that 80.2%, 90.3%, and 97.3% of NBB dye degraded as a result of enhanced photocatalytic activity of synthesized CuO–Ag/rGO. The research provides valuable insights into the design and development of advanced nanomaterials for efficient and sustainable wastewater treatment applications.

Regeneration of oxygenated functional groups on thermally reduced graphene oxide nanosheets via diluted oxygen DBD cold plasma

Although stacked graphene oxide (GO) possesses abundant oxygenated functional groups, it suffers from limited specific surface area. This study aims to enhance the specific surface area of graphene oxide via thermal expansion and subsequently oxygenated functional groups using a dielectric barrier discharge (DBD) cold plasma. GO was synthesized via improved Hummer's method, followed by rGO reduction at 520 ℃. The rGO was treated by DBD cold plasma with N2 and O2 gases at various powers and exposure times. The resulting samples were characterized using several techniques, including TPD, FTIR, Boehm titration, BET, Raman spectroscopy, FESEM and EDS. The results showed that increasing O2 in the feed gas up to 47 % and plasma power enhanced oxygenated functional groups on plasma-functionalized rGO (PF-rGO). The exposure time significantly influenced the oxygen content of the functional groups; PF-rGO samples with 5 min exposure time exhibited superior specific surface area, water stability, and Cd2+ adsorption capacity compared to samples treated for 15 min. As plasma exposure time increased, layer stacking and oxygenated group density increased. Raman spectroscopy confirmed the enhancement of oxygen groups on the rGO surface treated with O2-N2 plasma. These findings provide valuable insights for designing and developing of graphene-based materials with tailored properties and enhanced performance for energy-related applications.

Cr-Doped CeO2 Nanocrystals Supported on Reduced Graphene Oxide Nanosheets for Electrocatalytic Hydrogen Evolution

Cr-Doped CeO₂ Nanocrystals Supported on Reduced Graphene Oxide Nanosheets for Electrocatalytic Hydrogen Evolution

Enzymatic reduction of graphene oxide by a secreted hydrogenase

Although reducing graphene oxide (GO) is a promising method for producing graphene, it involves high energy consumption and serious pollution. Here, an eco-friendly and cost-effective method to reduce GO was developed, in which GO was reduced by a fermentation-medium system containing self-secreted [FeFe]-hydrogenase (CFM-H2ase). It was found that GO could be rapidly reduced by hydrogen which was catalyzed by the fermentation medium of Escherichia coli that heterologously expressed [FeFe] hydrogenase. The reduced GO nanosheets were characterized and confirmed by Raman, XRD, and XPS analysis, which indicated a high reduction ratio was achieved. Further analysis revealed that the [FeFe] hydrogenase secreted by the genetically engineered E. coli cells was responsible for the catalysis of hydrogen-induced GO reduction, which was the underlying mechanism for GO reduction by the CFM-H2ase system. This work demonstrated a new enzymatic approach for GO reduction, which would be helpful in developing a more sustainable graphene industry.

P-n heterogeneous Sb2S3/SnO2 quantum dot anchored reduced graphene oxide nanosheets for high-performance lithium-ion batteries.

Antimony sulfide (Sb2S3) has a high theoretical specific capacity due to its two reaction mechanisms of conversion and alloying during the Li+-(de)intercalation process, thus becoming a promising lithium-ion battery (LIB) anode material. However, its poor inherent conductivity and large volume expansion during repeated Li+-(de)intercalation processes greatly hinder the in-depth development of Sb2S3 based LIB anode materials. Herein, an Sb2S3/SnO2@rGO composite was prepared by using an interface engineering technique involving metal-containing ionic liquid precursors, in which Sb2S3/SnO2 quantum dots (QDs) as p-n heterojunctions are uniformly anchored on the surface of reduced graphene oxide (rGO). The p-n heterogeneous interface between Sb2S3 and SnO2 QDs induces an internal electric field, promoting the electronic/ion transport during electrochemical reactions, and the QD-sized Sb2S3/SnO2 heterostructure with a larger surface area provides more active sites for Li+-(de)intercalation reactions. In addition, the rGO matrix acts as a buffer to prevent the aggregation of active Sb2S3 and SnO2 QDs, alleviate the volume expansion, and enhance the conductivity of the composite during repeated cycles. These advantages endow the designed Sb2S3/SnO2@rGO electrode with excellent reaction kinetics and good long cycling stability. As an anode material of LIBs, it can still provide a reversible specific capacity of 474 mA h g-1 after 2000 cycles at a high current density of 3.0 A g-1, which is superior to those of most of the previously reported Sb2S3-based carbon materials. The p-n heterostructure construction strategy of nano-metal sulfide/metal oxides in this work can provide inspiration for the design and synthesis of other advanced energy storage materials.

Hydrothermally synthesized nickel ferrite nanoparticles integrated reduced graphene oxide nanosheets as an electrode material for supercapacitors

Hydrothermally synthesized nickel ferrite nanoparticles integrated reduced graphene oxide nanosheets as an electrode material for supercapacitors

Enhanced Polarization Properties of Holographic Storage Materials Based on RGO Size Effect.

Polarized holographic properties play an important role in the holographic data storage of traditional organic recording materials. In this study, reduced graphene oxide (RGO) was introduced into a phenanthraquinone-doped polymethylmethacrylate (PQ/PMMA) photopolymer to effectively improve the orthogonal polarization holographic properties of the material. Importantly, the lateral size of RGO nanosheets has an important influence on the polymerization of MMA monomers. To some extent, a larger RGO diameter is more conducive to promoting the polymerization of MMA monomers and can induce more PMMA polymers to be grafted on its surface, thus obtaining a higher PMMA molecular weight. However, too large of a RGO will lead to too much grafting of the PMMA chain to shorten the length of a single PMMA chain, which will lead to the degradation of PQ/PMMA holographic performance. Compared with the original PQ/PMMA, the diffraction efficiency of the RGO-doped PQ/PMMA photopolymer can reach more than 11.4% (more than 3.5 times higher than the original PQ/PMMA), and its photosensitivity is significantly improved by 4.6 times. This study successfully synthesized RGO-doped PQ/PMMA high-performance photopolymer functional materials for multi-dimensional holographic storage by introducing RGO nanoparticles. Furthermore, the polarization holographic properties of PQ/PMMA photopolymer materials can be further accurately improved to a new level.

Ultra−fast and stable dispersion of graphene oxide in lubricant oil toward excellent tribological property

Graphene oxide (GO) nanocomposite lubricants have been verified with excellent anti−wear and anti−friction properties. However, the rapid transfer of hydrophilic GO nanosheets into hydrophobic lubricants still faces great challenges. In this work, a series of nanocomposite lubricants were successfully fabricated by a simple phase transfer process without complex chemical modification. With the assistance of ethanol and oleylamine, the GO nanosheets initially dispersed in the water phase could be quickly transferred to the mineral oil within 20 s after hand-shaking the immiscible two−phase system. Moreover, the phase−transferred GO nanosheets were greatly stable in the mineral oil for at least seven days. The tribological properties of the GO nanocomposite lubricants had been studied by a macroscopic ball−on−disk friction test. The tribological behavior of the obtained nanocomposite lubricants showed that when 0.1 mg/mL GO was dispersed into mineral oil, the minimum average friction coefficient was 0.140, which was 72% lower than that of mineral oil. The universality of the phase transfer process was verified by the reduced GO nanosheets. This physical phase transfer method must be simple, effective, and environment−friendly to prepare nanocomposite lubricants.

Multi-functionalization of reduced graphene oxide nanosheets for tumor theragnosis: Synthesis, characterization, enzyme assay, in-silico study, radiolabeling and in vivo targeting evaluation

BackgroundIn this study, a combination of nanotechnology, organic synthesis and radiochemistry were utilized in order to design an efficient nano-system conjugated with a suitable radionuclide and an antitumor agent for possible application as tumor theragnostic agent.MethodFour novel compounds (3 and 4a-c) bearing tetrahydroquinazoline-7-sulfonohydrazide or 1,2,3,4-tetrahydroquinazoline-7-sulfonamide scaffold were designed. Then, docking study predicted that the compounds can be considered as potential inhibitors for PARP-1. Following that; the four compounds were synthesized and properly characterized using 1HNMR, 13CNMR, IR and Mass spectroscopy. The cytotoxic effect of the four compounds was evaluated against breast cancer cell line (MDA-MB-436), where compound 3 showed the most promising cytotoxic effect. The inhibitory effect of the four compounds was evaluated in vitro against PARP-1.ResultCarboxylated graphene oxide nanosheets (NGO-COOH) were synthesized by a modified Hummer's method and has size of range 40 nm. The NGO-COOH nanosheets were proven to be safe and biocompatible when tested in vitro against normal human lung fibroblast cells (MRC-5). The prepared NGO-COOH nanosheets were conjugated with compound 3 then radiolabeled with 99mTc to yield 99mTc-NGO-COOH-3 with a radiochemical yield of 98.5.0 ± 0.5%. 99mTc-NGO-COOH-3 was injected intravenously in solid tumor bearing mice to study the degree of localization of the nano-system at tumor tissue. The results of the study revealed, excellent localization and retention of the designed nano-system at tumor tissues with targeting ratio of 9.0.ConclusionStirred a new candidate tumor theragnostic agent that is safe, selective and stable.Graphical abstract

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.