Three-dimensional Reduced Graphene Oxide Research Articles

Development of a highly sensitive and selective electrochemical aptasensor for the detection of Staphylococcus aureus in various samples

Food poisoning caused by toxins produced by Staphylococcus aureus (S. aureus) is a significant global public health concern, impacting both developing and developed countries. One effective method for detecting S. aureus is the use of electrochemical aptasensors. This study introduces a highly sensitive and selective electrochemical aptasensor designed for detecting of S. aureus bacteria. The aptasensor incorporates ferrocene (Fc) as an electrochemical signal tag, which is covalently bonded to a zeolitic imidazolate framework-8 (ZIF-8). To enhance the performance of the working electrode, a nanocomposite of three-dimensional reduced graphene oxide and chitosan is used to create a nanomaterial film with a large surface area and excellent conductivity. The S. aureus-specific aptamer sequence is immobilized as the bio-recognition element, and cDNA-ZIF-8-Fc is hybridized with the immobilized aptamer. Differential pulse voltammograms of the modified electrode are recorded before and after the interaction between the immobilized aptamer and S. aureus. The changes in peak current serve as the analytical signal for the quantitative measurement of S. aureus. The designed aptasensor can detect S. aureus within a linear concentration range of 15.0 to 1.5 × 107 CFU mL−1, with a limit of detection (LOD) of 5.3 CFU mL−1. The results demonstrate that the aptasensor effectively quantifies S. aureus selectively in the presence of other bacterial species. Additionally, satisfactory results are obtained when measuring S. aureus in tap water and milk samples.

Heterostructured Co3Se4/CoSe2@C nanoparticles attached on three-dimensional reduced graphene oxide as a promising anode towards Li-ion batteries

Heterostructured Co3Se4/CoSe2@C nanoparticles attached on three-dimensional reduced graphene oxide as a promising anode towards Li-ion batteries

Theoretically endured defect-engineered antimony selenide nanocrystals grafted within three-dimensional reduced graphene oxide hollow microspheres with large open cavities as polysulfide barrier for robust sulfur kinetics

Theoretically endured defect-engineered antimony selenide nanocrystals grafted within three-dimensional reduced graphene oxide hollow microspheres with large open cavities as polysulfide barrier for robust sulfur kinetics

Unraveling the Phosphorus Adsorption Mechanisms in Three-dimensional Reduced Graphene Oxide Materials.

To prevent eutrophication, controlling the phosphate concentration levels is one of the most important issues in surface water management. One of the most utilized methods is phosphate adsorption. However, its application faces a bottleneck due to the unclear understanding of adsorption and interaction mechanisms. The present work unlocks the phosphorus adsorption mechanisms in three-dimensional reduced graphene oxide with different reduction levels and pore sizes to remove phosphate from water using experiments and multiscale simulations. Experiments were performed to evaluate the influence of pH, ionic strength, and temperature on the adsorption. Molecular Dynamics and Ab Initio simulations evaluated the influence of the pore size and oxidation degrees of the materials. We show that the adsorption capacity of the materials increases with increasing pH and ionic strength and decreasing temperature. It is observed that the more oxidized the material and the less compact the structure, the better the adsorption. These results are theoretically explained in terms of the interaction of functional groups and the clustering of phosphate ions, which results in better adsorption in materials with larger pores. The underlying mechanisms for the 3D-reduced graphene oxide performance were confirmed by spectroscopy analysis. All the results show that 3D-reduced graphene oxide can sorb phosphate in different complex water remediation systems with characteristics that can be modulated by changing the material synthesis method.

SnOx embedded into 3D RGO network for enhanced photoconductive performance

In this study, tin dioxide with vacancies (SnOx) was compounded with three-dimensional reduced graphene oxide (3D RGO) to obtain SnOx/3D RGO. The morphology, optical properties and structural composition of SnOx/3D RGO were analyzed by a series of techniques, and the photoconductive properties of the SnOx/3D RGO composites with different mass fractions of RGO were investigated. The photocurrent density of SnOx/3D RGO at 3D RGO mass fraction of 1.5 % reached a maximum value of 2.77 × 10−4 A/cm2, which was about twice and 1.2 times as large as that of SnOx and SnOx/2D RGO (two-dimensional reduced graphene oxide), respectively. In the linear scanning voltammetry and Mott-Schottky analysis results, SnOx/3D RGO exhibited the highest photocurrent (6.34 × 10−3 A/cm2) intensity at 1.0 V bias and the largest carrier density (2.61 × 1021cm−3). This was due to the fact that RGO played a charge transfer role in the composite material in both 2D and 3D structures. In contrast, the porous 3D RGO could connect separate lamellae, which prevented the aggregation of layers and enhanced the electron transfer, thus exhibiting superior performance than 2D graphene.

Synthesis of oxygen vacancy-engineered Fe2O3 nanospheres on three-dimensional reduced graphene oxide for ultra-energy density performance of asymmetric supercapacitors

The synthesis of oxygen vacancy (VO) -engineered Fe2O3 (Fe2O3-x) nanospheres on three-dimensional reduced graphene oxide (3D rGO/Fe2O3-x) is proposed via a gentle and high-efficiency hydrothermal approach under reducing conditions for a high-performance asymmetric supercapacitors. The smooth and rounded 3D rGO/Fe2O3-x hydrogel appears to be intact, which possesses extremely light weight and excellent strength. The micromorphology of 3D rGO/Fe2O3-x presents a 3D interconnected macroporous network structure, and the Fe2O3-x nanospheres are distributed on the surface of 3D rGO. The specific capacity of the 3D rGO/Fe2O3-x is up to 273.2 mAh/g. An asymmetric supercapacitor 3D rGO/Fe2O3-x||3D rGO exhibits an ultrahigh energy density of 114 Wh/kg at a power density of 140 W/kg. Over 20000 cycles, the capacitance retention fading and the coulombic efficiency are 6.18% and ∼100%, respectively. Outstanding supercapacitor performances of the 3D rGO/Fe2O3-x||3D rGO are attributed to the formation of the VOs in Fe2O3 crystal structure and the distribution of Fe2O3-x nanospheres on the 3D rGO. The 3D rGO/Fe2O3-x displays great potential for utilization as high-performance supercapacitors.

Intrinsic pentagon defect engineering in multiple spatial-scale carbon frameworks for efficient triiodide reduction

Intrinsic topological defect engineering has been proven as a promising strategy to elevate the electrocatalytic activity of carbon materials. However, the controllable construction of high-density and specific topological defects in carbon frameworks to reveal the relationship between reactivity and defect structure remains a challenging task. Herein, the intrinsic pentagon carbon sites that can favor electron overflow and enhance their binding affinity towards the intermediates of catalytic reaction are firstly presented by the work function and the p-band center calculations. To experimentally verify this, the cage-opening reaction of fullerene is proposed and utilized for synthesizing carbon quantum dots with specific pentagon configuration (CQDs-P), subsequently utilizing CQDs-P to modulate the micro-scale defect density of three-dimensional reduced graphene oxide (rGO) via π-π interactions. The multiple spatial-scale rGO-conjugated CQDs-P structure simultaneously possesses abundant pentagon and edge defects as catalytic active sites and long-range-ordered π electron delocalization system as conductive network. The defects-rich CQDs-P/rGO-4 all-carbon-based catalyst exhibits superb catalytic activity for triiodide reduction reaction with a high photoelectric conversion efficiency of 8.40%, superior to the Pt reference (7.97%). Theoretical calculations suggest that pentagon defects in the carbon frameworks can promote charge transfer and modulate the adsorption/dissociation behavior of the reaction intermediates, thus enhancing the electrocatalytic activity of the catalyst. This work confirms the role of intrinsic pentagon defects in catalytic reactions and provides a new insight into the synthesis of defects-rich carbon catalysts.

Constructing graphene-based aerogel with bi-continuous interpenetrating networks as a multi-functional microwave absorber

The design of three-dimensional networks in graphene-based aerogels is an effective strategy for fabricating a lightweight microwave absorber with strong absorption and broad effective bandwidth. Herein, a multi-functional aerogel with bi-continuous interpenetrating networks comprised of reduced graphene oxide (RGO) and cellulose nanofiber (CNF) was developed via an “ice-dissolving” (freezing and solvent exchange) and subsequent annealing strategy. Different from the conventional step-by-step construction of two independent networks, the bi-continuous interpenetrating networks were simultaneously built in a one-step freezing process. Notably, the network structure of the aerogel can be tuned by adjusting the concentration of CNF (CCNF) during the freezing stage. When the CCNF increased from 2 to 8 wt%, the network structure transitioned from a single three-dimensional RGO skeleton to ordered bi-continuous interpenetrating networks, and then to a disordered CNF/RGO mixed network. The mutual contributions from the RGO skeleton and CNF network endowed the aerogel (14.96 mg cm−3) with improved conduct loss and optimized characteristic impedance, leading to an excellent microwave absorption capacity. Consequently, the aerogel achieved a maximum reflection loss of −68.3 dB and an effective bandwidth of 6.9 GHz, respectively. Moreover, the unique network structure also enabled the sample to have superior noise absorbing performance (normalized absorption coefficient of 0.894 in 250–6300 Hz) and good structural stability. This strategy provides a facile avenue for constructing multi-functional aerogels with bi-continuous interpenetrating networks for both microwave absorption and noise absorption applications.

Development of new magnetic nanocomposite designed by reduced graphene oxide aerogel and HKUST-1, and its catalytic application in the synthesis of polyhydroquinoline and 1,8-dioxo-decahydroacridine derivatives

In this study, new magnetic reduced graphene oxide aerogel/HKUST-1 nanocomposite was designed and synthesized given the transformation of graphene oxide sheets to three-dimensional reduced graphene oxide aerogel, the in-situ magnetization of aerogel substrate, and the in-situ formation of HKUST-1 particles. Apart from characterizing the chemistry and structure of the designed magnetic nanocomposite (FT-IR, EDX, ICP, FE-SEM, DLS, XRD, VSM, and TG analyses), its catalytic performance was evaluated in the one-pot synthesis of biologically active 1,8-dioxo-decahydroacridine and polyhydroquinoline derivatives. The combination of magnetized reduced graphene oxide aerogel and HKUST-1 in the form of a new heterogeneous magnetic nanocatalyst was accompanied by a high synergetic catalytic effect in the symmetric and unsymmetrical Hantzsch condensation reactions. Compared to previous research studies, the pharmaceutical 1,8-dioxo-decahydroacridine and polyhydroquinoline derivatives can be synthesized using a partial amount of this nanocatalyst with a high percentage of yields in a short reaction time.

Improving the anti-corrosive performance of epoxy/zinc composite coatings with N-doped 3D reduced graphene oxide

Three-dimensional reduced graphene oxide (3DRGO) doped with N heteroatoms was innovatively incorporated into a Zn-containing epoxy (EP/Zn) composite coating. Comprehensive investigations that introducing 3DRGO significantly improved the anti-corrosion performance of the coating, and the optimal 3DRGO content was only 0.05 wt%. The effects of both the spatial structure and chemical doping of graphene on the surface protection performance of their EP/Zn coating were revealed for the first time. Compared with the conventional 2-dimensional reduced GO (RGO) sheets and 3D graphene (3DG) with similar 3D structures, 3DRGO exhibited superior effect on promoting the corrosion resistance of its composite coating. This can be attributed to not only the unique 3D porous strut structure of 3DRGO, but also its N-doping, which plays important roles in increasing its interaction with the epoxy matrix, preventing 3DRGO agglomeration, improving the barrier property of the coating, facilitating the construction of an electrical conduction network between Zn particles, and exploiting the cathodic protection function of Zn more efficiently.

Y-tetrahedral DNA nanostructures assisted dual signal aptasensor for simultaneous detection of isocarbophos and edifenphos

We reported a novel gold particles-modified three-dimensional reduced graphene oxide (3D-rGO/AuNPs) electrochemical aptasensor for the simultaneous detection of isocarbophos and edifenphos. In this study, the use of different metal ions resulted in the generation of discrete differential pulse voltammetry (DPV) peaks. These discrete peaks allowed the identification of different pesticides and their respective concentrations, thereby achieving simultaneous detection. Five designed aptamers were processed to form a Y-shaped tetrahedral DNA nanostructure (Y-TDN) as a skeleton, which could specifically bind to the aptamers of edifenphos and isocarbophos. Herein, Pb2+ was used to label an edifenphos aptamer (Pb2+-APTEd), and Cd2+ was used to label an isocarbophos aptamer (Cd2+-APTIs), respectively. Notably, due to the force of specific recognition between aptamer and targets being stronger than the force between the aptamer and the complementary strand of Y-TDN, Pb2+-APTEd and Cd2+-APTIs were dissociated from Y-TDN, thereby causing the reduced oxidation currents of Pb2+ and Cd2+. In addition, 3D-rGO/AuNPs could enhance the electron transfer ability to amplify a signal, and immobilize the aptamer on the electrode surface through Au-S bonds. Linear calibration curves were obtained over the concentration range of 0.01–1000 ng/mL for edifenphos and 0.1–1000 ng/mL for isocarbophos with a limit of detection (LOD) was 3.3 pg/mL and 33 pg/mL, respectively. This conceptual model provides the theoretical basis for the simultaneous detection of environmental contaminants, with the flexibility to be reprogrammed by simple modification of the aptamer for the detection of various toxins, antibiotics, and other small contaminants.

N doping porous carbon embedded in self-assembled three-dimensional reduced graphene oxide networks for electrochemical hydrogen storage

Electrochemical hydrogen storage can realize reversible hydrogen absorption and desorption at room temperature and pressure, which has attracted extensive attention recently. A nanosheet-like reduced graphene oxide (rGO)-porous carbon composite with N-doping defect is prepared via a facile annealing, followed by hydrothermal and freeze-drying process. After N-doping, the porous carbon materials exhibit rich pore structure, and high pyridine nitrogen and pyrrolic nitrogen content. Adding them into the graphene self-assembly process, the aggregation tendency of graphene sheets can be reduced, the composite shows a free-standing 3D porous structure. Benefit from the synthetic effect between the rGO conductive network, the hierarchical porous structure, and the doping of N atoms, the rGO-N800 delivers a high hydrogen storage capacity of 266.3 mAh g−1 at 200 mA g−1 after 100 cycles. Moreover, the reversible capacities of the composite can reach 288.4, and 267.1 mAh g−1 at 1000 mA g−1 and 2000 mA g−1, respectively. The outstanding electrochemical performance of the composite demonstrates a promising direction for design carbon-based hydrogen storage materials.

Three-dimensional reduced graphene oxide anchored MoS2@C core-shell nanoparticles as high performance materials in supercapacitor application

Three-dimensional (3D) reduced graphene oxide (rGO) anchored carbon-coated MoS2 core-shell nanoparticles (MoS2@C-rGO) has been developed successfully through a simple one-pot hydrothermal process. The 3D MoS2@C-rGO nanocomposite consists of carbon coated MoS2 nanoparticle clusters (MoS2@C) and rGO nanosheets. The homogenously distributed and intercalated MoS2@C nanoparticles between rGO nanosheets form a highly conductive 3D carbon network with rGO, and present a hierarchical pore size structure, enabling fast ion and electron transport, as well as remarkable specific surface area. The 3D MoS2@C-rGO demonstrates an extraordinary specific capacitance of 1105 Fg−1 when subjected to a current density of 1 Ag−1. The 3D MoS2@C-rGO is also exceptionally cycle-stable, as demonstrated by the fact that it retains 96.3 % of its initial capacitance even after 5000 cycling cycles at 1 Ag−1. This symmetric supercapacitor is made with electrodes that are composed of MoS2@C-rGO, and it has a power density of 16.7 kW kg−1 and a specific capacitance of 405 Fg−1 at a current density of 1 Ag−1. Because of these properties, high-performance supercapacitors might benefit from having their electrodes made out of 3D MoS2@C-rGO.

Synthesis of a three-dimensional reduced graphene oxide aerogel decorated with (Fe3O4@SiO2–NH2)–COC2H4COOH for adsorption of heavy metal cations

Hereunder, a new method for the synthesis of a three-dimensional (3D) reduced graphene oxide (r-GO) nanohybrid is presented by the use of a synthetic novel crosslinker ((Fe3O4@SiO2–NH2)–COC2H4COOH) designed for multifunctional purposes. This crosslinker not only provide a three-dimensional structure for the adsorbent (increasing adsorption capacity), but also it enables the magnetically separation of the 3D r-GO nanohybrid. According to high-resolution transmission electron microscopy (HRTEM), the r-GO sheets were well decorated with nearly spherical (Fe3O4@SiO2–NH2)–COC2H4COOH nanoparticles with an average size of 60 nm. More importantly, the X-ray photoelectron spectroscopy (XPS) showed that the 3D r-GO nanohybrid contains several oxygenous and nitrogenous functional groups that makes it an ideal heavy metallic cations adsorbent. In addition, the synthesized 3D r-GO nanohybrid showed a maximum adsorption capacity of ∼455, 448 and 232 mg/g for lead, cadmium, and copper, respectively; besides, the exothermic adsorption of these cations followed a pseudo-second-order model. It was also found that an effective metal desorption step can be achieved by using a mixture of nitric acid and acetonitrile. The adsorption percentage of the 3D r-GO nanohybrid remained unchanged after five cycles of adsorption–desorption step. At last, the experimentally observed adsorption/desorption behaviors were justified using the density functional theory (DFT).

The effect of phosphorus and nitrogen dopants on structural, microstructural, and electrochemical characteristics of 3D reduced graphene oxide as an efficient supercapacitor electrode material

Supercapacitors are environmentally friendly and safe energy storage devices for diverse applications. The electrode material's structural, microstructural, and electrochemical properties are crucial determinants of supercapacitor capacity. One effective method to improve electrode performance is introducing doping heteroatoms or synthesizing composite materials. In this study, three-dimensional reduced graphene oxide (3D rGO) doped with Phosphorus, Nitrogen, or both (N/P co-doped) was synthesized for high-efficiency, supercapacitors using a facile, fast, and cost-effective hydrothermal process. The hydrothermal reduction of graphene oxide involved substituting Phosphorus and Nitrogen elements with carbon atoms. Moreover, the effect of dopants on structural and microstructural characteristics of 3D rGO was evaluated using different techniques, and the electrochemical characteristics were evaluated by cyclic voltammetric (CV) analysis, galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). The specific capacitance of 3DN/PrGO on Ni foam reached 648 F g−1 at 1 Ag−1, in a voltage range of −0.6 –0.6 V (vs. Ag/AgCl), using 6 M KOH as the electrolyte. High energy density and power density of 6.1 wh/kg and 513 w/kg were obtained, respectively. The stability test was also conducted, and appropriate stability over 100 charging and discharging cycles was observed. The considerable performances are mainly due to the combined effect of pseudocapacitive properties of Nitrogen and Phosphorus dopants, improved wettability, and the porous structure of 3D rGO, which provides suitable electroactive sites and simplifies the electron/ion transfer for the electrochemical reactions.

Reduced graphite oxide wrapped ZnO-SnO2 hollow nanospheres with as anodes for hybrid high energy density supercapacitors

As cathode materials for supercapacitors, metallic oxide composites have high theoretical capacities, which have received widespread attentions. However, due to the rapid capacity degradation，it remains a challenge to the development of metallic oxides. A composite electrode material for supercapacitors scheme is proposed in this paper, which is constructed by novel hybrid ZnO-SnO2 nanoparticles, annealed from hollow nanospheres ZnSn(OH)6, and is well encapsulated within a three-dimensional reduced graphene oxide (RGO). The [email protected]2 electrodes show excellent performances with high initial coulomb efficiency of 98.9 %, high reversible capacities (581.8 F g−1 at 0.5 A g−1), enhanced long-term cycling with capacity retention rate of 98 % and fantastic rate capability (440.9 F g−1 at 5A g−1) after 1000 cycles. When assembled with AC cathodes, the full supercapacitors exhibit excellent electrochemical performances (26 Wh·kg−1 at 0.75 kW·kg−1, 8.2 W·kg−1 at 9.87 kW·kg−1). This method also provides a new idea for the preparation of other bimetallic selenides, oxides, sulfides or phosphides with improved electrochemical properties.

Ultrafine FeF3·0.33H2O Nanocrystal-Doped Graphene Aerogel Cathode Materials for Advanced Lithium-Ion Batteries.

FeF3 has been extensively studied as an alternative positive material owing to its superior specific capacity and low cost, but the low conductivity, large volume variation, and slow kinetics seriously hinder its commercialization. Here, we propose the in situ growth of ultrafine FeF3·0.33H2O NPs on a three-dimensional reduced graphene oxide (3D RGO) aerogel with abundant pores by a facile freeze drying process followed by thermal annealing and fluorination. Within the FeF3·0.33H2O/RGO composites, the three-dimensional (3D) RGO aerogel and hierarchical porous structure ensure rapid diffusion of electrons/ions within the cathode, enabling good reversibility of FeF3. Benefiting from these advantages, a superior cycle behavior of 232 mAh g-1 under 0.1C over 100 cycles as well as outstanding rate performance is achieved. These results provide a promising approach for advanced cathode materials for Li-ion batteries.

Ti3CNTx MXene/rGO scaffolds directing the formation of a robust, layered SEI toward high-rate and long-cycle lithium metal batteries

The practical usage of lithium (Li) metal anodes has been hindered by the inherent uncontrolled growth of Li dendrites during stripping/plating. Approaching regulation of uniform Li deposition and robust solid-electrolyte interphase (SEI) is of significance. Herein, we utilized the unique surface chemistry of two-dimensional titanium carbonitride (Ti3CNTx) and the three-dimensional reduced graphene oxide (rGO)-based conductive scaffold architecture, to regulate the Li nucleation and SEI. The lithiophilic functional groups on Ti3CNTx improve the charge-transfer-promoted decomposition of LiN(CF3SO2)2 and resulting in the formation of a uniform SEI layer decorated with evenly distributed LiF and ordered layered Li2O, as evidenced by cryogenic transmission electron microscopy. The Ti3CNTx-rGO-Li electrodes based full cells with LiFePO4 guarantee a superior cycling lifespan over 900 cycles with a capacity retention of 77.7% at 30 C. This work demonstrates that through surface engineering and multiscale architecture design, the suppression of Li dendrites and formation of robust SEI layer can be achieved simultaneously.

Fabrication and efficient electromagnetic waves attenuation of three-dimensional porous reduced graphene oxide/boron nitride/silicon carbide hierarchical structures

In this work, hierarchical hybrid composites consisting of porous three-dimensional reduced graphene oxide (3D-rGO) skeleton and lamellar boron nitride (BN)/silicon carbide (SiC) coatings are prepared by chemical vapor infiltration (CVI) process. The graphene framework prepared by 3D printing and frozen self-assembly exhibits a lightweight structure and a perforated conductive network, which extends the transmission path of incident microwaves. The introduced ceramic coatings can effectively tune the impedance matching degree and supply a lossy phase, and the hierarchical structure of the composites enhances the multiple scattering of the incident microwaves. As expected, the 3D-rGO/BN/SiC composites possess an excellent absorbing performance with a minimum reflection loss value of –37.8 dB, and the widest effective absorbing bandwidth (RL < –10 dB) of 5.90 GHz is obtained. The controllable fabrication of composites can provide a guideline for rational design and fabrication of high-performance electromagnetic waves absorbing materials in practical applications.

Nickel hexacyanoferrate nanoparticle-decorated 3D rGO composites-based electrochemical sensing platform for detectionof di-2-ethylhexyl phthalate.

A label-free and efficient electrochemical (EC) sensing platform for di-2-ethylhexyl phthalate (DEHP) was developed based on in situ probe nickel hexacyanoferrate nanoparticle (NiHCF NP)-decorated three-dimensional reduced graphene oxide (3D rGO) composites. NiHCF NPs in the composites as an in situ probe show a pair of well-defined peaks with good reversibility and stability. Coupling 3D rGO with NiHCF NPs not only improved the electron transfer capability of NiHCF NPs but also provided more sites for aptamer immobilization. The synthesized NiHCF NP-decorated 3D rGO composites were used to act as a substrate for the immobilization of anti-DEHP aptamer by the covalent bonding method. The designed EC sensing platform displays excellent sensing performance for DEHP with a low detection limit of 3.64pg/L, and a linear working rangeof 0.01 - 1000ng/L. Theapplication of the sensing platform to actual environmental samples was studied and satisfactory results were obtained. Thus, the proposed EC sensing platform would provide a potential tool for efficient detection of pollutants in the environment.