3D Porous Reduced Graphene Oxide Research Articles

Nanomolar detection of essential amino acid in dairy products using a novel electrochemical sensor based on zinc cobaltite nanoflowers embedded porous 3D reduced graphene oxide

L-tryptophan (L-Trp) is a vital amino acid that sways neuronal function, immunity, and gut homeostasis, and its accurate detection in food samples is crucial. The aim of this study is to integrate zinc cobaltite (ZCO) nanoparticles and 3D porous reduced graphene oxide (rGO) on a screen-printed carbon electrode (SPCE) surface for building a novel electrochemical sensor to sensitively detect L-Trp in food products. A low-temperature aqueous solution method was employed in ZCO nanoflower synthesis and a hydrothermal approach was utilized to prepare 3D rGO. SEM, elemental mapping, XRD, Raman spectroscopy, XPS, and EIS characterizations were performed on the prepared nanocomposite, ZCO/3DrGO. Electrochemical experiments conducted with the cyclic and differential pulse voltammetric techniques were used for effectively assessing the catalytic power of ZCO/3DrGO/SPCE. With a low detection limit of 3 nM, high sensitivity of 19.53 μAμM−1cm−2, and a broad linear range of 0.08–5.93; 5.93–87.18 μM, the sensor demonstrated promising electrocatalytic activity towards L-Trp. Further, the reliability of the sensor was proved by analyzing its stability, repeatability, reproducibility, and selectivity towards L-Trp. The successful detection of L-Trp in dairy products (yogurt, milk, and cottage cheese) using the proposed sensor evinced its practical feasibility with high recovery of 98.16%–101.16% and low RSD of 2.8%.

Ultralight reduced graphene oxide/SiO2–C nanofibers composite aerogel decorated with Li0.35Zn0.3Fe2.35O4 nanoparticles with a three-dimensional bridging network for efficient electromagnetic wave absorption

Developing flexible, lightweight, and highly efficient electromagnetic wave (EMW) absorption materials was an effective strategy for mitigating the adverse health effects of microwaves. However, synthesizing flexible wave-absorbing aerogels via a novel method is challenging. In this study, a 3D porous reduced graphene oxide (RGO)/SiO2–C nanofibers (NFs)/Li0.35Zn0.3Fe2.35O4 (LZFO) flexible composite aerogel with a crosslinked structure was synthesized via electrospinning, freeze-drying, and in situ curing. To achieve this, electrospun SiO2 and polyacrylonitrile NFs, graphene oxide (GO), and LZFO nanoparticles were uniformly dispersed in an aqueous solution containing (Al(H3PO4)3) as a crosslinking agent and a crosslinked aerogel was formed by freeze-drying, pre-oxidation and carbonization. The obtained aerogels exhibited a good 3D porous structure. By introducing (Al(H3PO4)3) the cell binding force between the 0D, 1D and 2D materials was improved. Further, the introduction of SiO2 NFs reduced the brittleness of the C NFs and improved the flexibility of the aerogel. Under 60% strain, the stress reached 132 kPa, and a complete closed loop was formed. The RGO and C NFs conductive network coupled with the LZFO nanoparticles magnetic network form an ideal impedance matching. The minimum reflection loss (RLmin) of the RGO/SiO2–C NFs/LZFO-2 aerogel reached −55.2 dB (2.5 mm), and effective absorption bandwidth (EAB) was 5.5 GHz (2 mm) to cover the entire X-band. Moreover, by adjusting the matching thickness (2–4 mm), the RLmin was below −20 dB, and more than 99% of the EMW was absorbed. This study provides a new way to develop flexible absorbent materials for human protection.

Synthesis of Ag Nanoparticles Dispersed on Co3O4–3D Porous Reduced Graphene Oxide and their Application for Electrochemical Sensing of Hydrogen Peroxide

Ag nanoparticles dispersed on Co3O4/3D porous reduced graphene oxide (Ag/Co3O4/rGO) were successfully synthesized through sol–gel method and used for fabricating a novel nonenzymatic hydrogen peroxide (H2O[Formula: see text] sensor. The structure and morphology of anocomposites were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The electrochemical properties of the sensor were investigated by cyclic voltammetry and amperometry. The experimental results suggest that the composites have an excellent catalytic property toward dopamine with a wide linear range from 0.5[Formula: see text][Formula: see text]M–6.48[Formula: see text]mM, a low detection limit of 0.17[Formula: see text][Formula: see text]M ([Formula: see text]) and high sensitivity of 413.72[Formula: see text][Formula: see text]A[Formula: see text]mM[Formula: see text] cm[Formula: see text]. In addition, the sensor exhibits long-term stability, good reproducibility and anti-interference.

Ultrasensitive Electrochemical Sensor Based on SnO2 Anchored 3D Porous Reduced Graphene Oxide Nanostructure Produced via Sustainable Green Protocol for Subnanomolar Determination of Anti-Diabetic Drug, Repaglinide

Herein, we have reported on a simple, environmentally friendly, and ultra-sensitive electrode material, SnO2@p-rGO, used in a clean sustainable manner for rapid electrochemical determination of an anti-diabetic agent, repaglinide (RPG). Three-dimensional porous reduced graphene oxide nanostructure (p-rGO) was prepared via a low-temperature solution combustion method employing glycine. The aqueous extract of agricultural waste “cotton boll peel” served as stabilizing and reducing agents for the synthesis of SnO2 nanoparticles. The structural and morphological characterization was carried out by XRD, Raman, SEM, EDX, FTIR, absorption, and TGA. The oxidation process of RPG was realized under adsorption controlled with the involvement of two protons and electrons. The sensor displayed a wider linearity between the concentration of RPG and oxidation peak current in the ranges of 1.99 × 10−8–1.45 × 10−5 M and 4.99 × 10−8–1.83 × 10−5 M for square-wave voltammetric and differential pulse voltammetric methods, respectively. The lower limit of detection value of 0.85 × 10−9 M was realized with the SWV method. The proposed sensor was applied for the quantification of RPG in fortified urine samples and pharmaceutical formulations. Furthermore, the sensor demonstrated reproducibility, long-term stability, and selectivity in the presence of metformin and other interferents, which made the proposed sensor promising and superior for monitoring RPG.

Co2P nanowire arrays anchored on a 3D porous reduced graphene oxide matrix embedded in nickel foam for a high-efficiency hydrogen evolution reaction.

Regulating the structural and interfacial properties of transition metal phosphides (TMPs) by coupling carbon-based materials with large surface areas to enhance hydrogen evolution reaction (HER) performance presents significant progress for water splitting technology. Herein, we constructed a composite substrate of a three-dimensional porous graphene oxide matrix (3D-GO) embedded in nickel foam (NF) to grow a Co2P electrocatalyst. Well-defined gladiolus-like Co2P nanowire arrays tightly anchored on the substrate show enhanced electrochemical characteristics for the hydrogen evolution reaction (HER) based on the promoting roles of 3D porous reduced GO (3D-rGO) derived from 3D-GO, which promotes the dispersion of active components, improves the rate of electron transfer, and facilitates the transport of water molecules. As a result, the obtained Co2P@3D-rGO/NF electrode exhibits superior HER activity in 1.0 M KOH media, achieving overpotentials of 36.5 and 264.7 mV at current densities of 10 and 100 mA cm-2, respectively. The electrode also has a low Tafel slope of 55.5 mV dec-1, a large electrochemical surface area, and small charge-transfer resistance, further revealing its mechanism of high intrinsic activity. Moreover, the electrode exhibits excellent HER stability and durability without surface morphology and chemical state changes.

Nanoconfined vanadium nitride in 3D porous reduced graphene oxide microspheres as high-capacity cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) are receiving considerable research highlights owing to their high safety and environment-friendliness. To implement this promising technology for grid-scale energy storage, effective cathode materials with high capacity, cycle stability, and electrochemical kinetics should be developed. Herein, the synthesis of uniquely structured porous VN-reduced graphene oxide composite (VN-rGO) microspheres through a facile spray pyrolysis process and their application as cathodes for ZIBs are introduced. The electrochemical reaction mechanism of VN-rGO microspheres with zinc ions is investigated through various in situ and ex situ analyses. During the initial charge process, VN phase transforms into the Zn3(OH)2V2O7·2H2O (ZVOH) phase. From the second cycle and on, the ZVOH phase undergoes zinc-ion ingress and egress processes. VN-rGO microspheres exhibit an unprecedented high capacity (809 mA h g−1 at 0.1 A g−1), high energy density (613 W h kg−1), and good rate capability (467 mA h g−1 at 2.0 A g−1). The cathode delivers a reversible capacity of 445 mA h g−1 after 400 cycles at 1.0 A g−1, which ascertains the robustness of the structure. The 3D porous rGO matrix to which VN nanocrystals are homogenously anchored accelerates the zinc-ion storage kinetics and endows the cathode with structural robustness.

Operando investigation on the fast two-phase transition kinetics of LiFePO4/C composite cathodes with carbon additives for lithium-ion batteries

In this study, we demonstrate the effect of adding one-dimensional (1D) vapor-grown carbon fiber (VGCF) as a carbon additive to increase the electronic conductivity of LiFePO4 cathode. Because, the 1D VGCF structure can provide rapid and long-pathways for electron transfer and regulate a better phase transition effect on LiFePO4 cathode compared to the other-dimensional carbon additives. Here, the olivine-type LiFePO4/C composite (LFP/C) cathode is basically derived from a sol-gel method, followed by a spray-dry technique to obtain a homogenous spherical morphology. The carbon additives of 0D super P, 1D VGCF and 2D or 3D porous reduced graphene oxide (PGO) nanosheets containing cathodes-based, such as bare LFP/C, LFP/C/VGCF and LFP/C/PGO, half-cells were fabricated and tested at a cut-off voltage of 2.0 – 3.8 V (vs. Li/Li+). Interestingly, the LFP/C/VGCF showed better performance than the bare LFP/C and LFP/C/PGO. Especially at high-rate cycle-life, the LFP/C/VGCF cathode attained capacity retention of 100% for 100 cycles at 1C/1C and 98.83% for 100 cycles at 1C/10C. It is due to the higher electronic conductivity (ca. 2.36 × 10−4 S cm−1) and Li+ ion diffusion coefficient (ca. 2.56 × 10−13 cm2 s−1) of LFP/C/VGCF cathode than the other electrodes. It can also provide better reversibility in a phase transition of LiFePO4/FePO4 phases during the charge/discharge cycle, further confirmed by in-situ XRD and micro-Raman techniques. The results indicated that the LFP/C/VGCF cathode displayed much faster kinetics behavior than bare LFP/C cathode.

Ingenious design of iron vanadate engulfed 3D porous reduced graphene oxide nanocomposites as a reliable electrocatalyst for the selective amperometric determination of furaltadone in aquatic environments

The improper discharge of organic toxicants, such as pesticides and antibiotics into water resources is a global problem that poses a serious threat to human health and the environment. In this work, an electrochemical sensor was developed for the selective detection of the antibiotic drug furaltadone (FLD) using iron vanadium oxide nanoparticles (Fe0.11V2O5.16, FeVO NPs) wrapped porous reduced graphene oxide nanosheets (p-rGO NSs) nanocomposites (FeVO/p-rGO NCs) as an electrocatalyst. A simple hydrothermal method was used to synthesize FeVO NPs and p-rGO NSs. The structural and morphological properties of the nanocomposites were characterized by different characterization techniques such as XRD, Raman, XPS, FE-SEM, and HR-TEM analyses. Electrochemical studies were performed using EIS, CV, and amperometric (i-t) techniques. The FeVO/p-rGO NCs sensor shows two wider linear ranges from 0.5 to 84 µM and 94 to 1319 µM with a low detection limit of 138 nM (44.74 µg kg−1). The proposed sensor showed good recovery results for the determination of FLD in industrial wastewater and lake water samples. The results obtained with real samples prove that the developed sensor demonstrated its practical applicability for detecting environmentally hazardous pollutants and protecting our aquatic ecosystem.

Multiple anionic Ni(SO4)0.3(OH)1.4 nanobelts/reduced graphene oxide enabled by enhanced multielectron reactions with superior lithium storage capacity

The multielectron reaction materials for lithium-ion batteries are interesting charge storage hosts for next-generation high-energy–density anodes. As a class of multiple-anion transition metal compounds (MATMCs), the layered Nickel hydroxide sulfate (NiSH) nanobelts integrate positive-charged cations and intercalated anions, can be expected to construct the advanced high-energy–density materials, but have not yet reported. Herein, the layered NiSH nanobelts grafting on the 3D porous reduced Graphene oxide (rGO) nanosheets were fabricated for the first time as the negative electrode of lithium-ion battery (denoted as NiSH@rGO) by a one-pot hydrothermal approach. As expected, the NiSH@rGO composite delivers a superior initial discharge capacity (1060 mAh g−1 at 200 mA g−1 after 230 cycles) and an exceptional rate capacity (991 mA g−1 at 2000 mA g−1). Through in-situ XRD, ex-situ SEM and TEM, we showed that the outstanding performance of NiSH@rGO anode originate from multielectron reaction mechanism and prominent structural, which render expose more active sites for charge storage, increase the surface wettability of anode, accelerate electron/ion diffusion and ensure the stability of the structure. Above that, it showed excellent lithium storage capacity and high-rate performance. Furthermore, a full cell composed of the NiSH@rGO anode and LiFePO4 cathode displays an impressive capacitance and low-capacity decay rate. Our findings fundamentally and experimentally provide insights into the multi-anionic compounds for markedly enhancing the performance of the multi-electron anodes for advanced high-capacity lithium-ion battery.

Designed assembly of Ni/MAX (Ti3AlC2) and porous graphene-based asymmetric electrodes for capacitive deionization of multivalent ions

The contamination of aquatic ecosystems by fluoride and heavy metal ions constitute an environmental hazard and has been proven to be harmful to human health. This study explores the feasibility of using asymmetric capacitive deionization (CDI) electrodes to remove such toxic ions from wastewater. An asymmetric CDI cell was fabricated using 2D Ni/MAX as an anode and 3D porous reduced graphene oxide (pRGO) as a cathode for the electrosorption of F−, Pb2+, and As(III) ions. A simple microwave process was used for the synthesis of Ni/MAX composite using fish sperm DNA (f-DNA) as a cross-linker between MAX nanosheets (NSs) and the metallic Ni nanoparticles (NPs). Further, pRGO anode was prepared through effective reduction of RGO using lemon juice as green reducing agent with the assist of f-DNA as a structure-directing agent for the formation of 3D network. With this tailored nanoarchitecture, pRGO and Ni/MAX electrodes exhibited a high specific capacitance of 760 and 385 F g−1, respectively. The fabricated Ni/MAX and pRGO based CDI system demonstrated a high electrosorption capacity of 68, 76, and 51 mg g−1 for the monovalent F−, divalent Pb2+, and trivalent As(III) ions at 1.4 V in neutral pH. Furthermore, Ni/MAX//pRGO system was successfully applied for the removal of total F(T), Pb(T), and As(T) ions from real industrial wastewater and contaminated groundwater. The present findings indicate that the fabricated Ni/MAX//pRGO electrode has excellent electrochemical properties that can be exploited for the removal of anionic and cationic metal ions from aqueous solutions in a CDI based system.

Three-dimensional porous reduced graphene oxide/PEDOT:PSS aerogel: Facile preparation and high performance for supercapacitor electrodes

Graphene derivatives have great potential in the field of energy storage, because of their high specific surface area, great electrical conductivity, and stable electrochemical properties. For the graphene-based electrodes with a three-dimensional (3D) porous structure, the interlayer stacking of the graphene sheets largely limits their capacitive performance, and thus hinders their wide applications. In this work, we successfully developed a lightweight, freestanding and 3D porous reduced graphene oxide (rGO)/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) composite aerogel by incorporating the conducting polymer PEDOT:PSS into interconnected rGO networks through a facile, low-cost and all-water-processable two-step synthesis route. PEDOT:PSS covering on the rGO sheets was found to not only prevent the stacking of rGO sheets, but also greatly improve the ion accessibility and mechanical stability of this highly porous spongy meshwork. Due to the synergistic effect of rGO and PEDOT:PSS, the aerogel electrodes delivered a high gravimetric specific capacitance (471 F g−1 at 0.2 A g−1), an excellent rate capability, and a remarkable capacitance retention (98.71% over 20,000 cycles at 20 A g−1). Furthermore, the aerogel-based symmetric supercapacitor exhibited a wide potential window (0–1.4 V) and an excellent energy storage performance. A high energy density of 48.18 Wh kg−1 with the power density of 1.4 kW kg−1 at 0.5 A g−1, or an energy density of 32.67 Wh kg−1 corresponding to the great power density of 14,000 W kg−1 at 5 A g−1 was achieved. These results demonstrate the great potential of the rGO/PEDOT:PSS aerogel as an excellent electrode material for energy storage applications.

3D porous graphene composite film embedded by Ni/NiO nanoparticles as freestanding electrodes for efficient energy storage devices

A 3D porous graphene composite film containing Ni/NiO hybrid nanoparticles (Ni/NiO NPs) is prepared by combining electrophoresis deposition and thermal H2 annealing techniques. The Ni/NiO NPs with a mean diameter of 45 nm are uniformly embedded on both the exterior and interior surfaces of reduced graphene, forming a 3D porous reduced graphene oxide composite film (Ni/NiO rGO). The insertion of Ni/NiO NPs into rGO greatly improves the electric conductivity and charge storage capability of the resultant Ni/NiO rGO film. By directly using it as freestanding electrodes, the fabricated lithium-ion battery and supercapacitor respectively exhibited high capacities of 758 mAh g−1@ 0.2 A g−1 and 430.8 F g−1@0.5 A g−1, an increase of 82.3-fold and 20.2-fold compared to the pure rGO electrode-based counterparts under the same condition.

Arc spectra of different solid reduced graphene oxide samples under microwave irradiation

It is often accompanied by an intense arc when solid-state graphene samples are irradiated by microwaves (MWs); however, arc spectra have not been studied. In this study, the arc spectra of reduced graphene oxide (RGO) powder, three-dimensional (3D) porous RGO, and RGO paper under MW irradiation were measured; these spectra exhibited diverse features. For the same reaction conditions and the same initial sample, the arc spectra should be the same if the reaction process and mechanisms are the same. Further analyses showed that the obtained RGO paper with an evident 2D band, a smaller D band, lower sheet resistance, and lower oxygen content was of higher quality than the RGO powder and 3D porous RGO obtained after MW irradiation. Based on these results, the diverse spectra may suggest different reaction processes and mechanisms. Overall, these findings provide novel insights into the preparation of graphene via MW reduction.

Synthesis of a zinc ferrite effectively encapsulated by reduced graphene oxide composite anode material for high-rate lithium ion storage

Effectively immobilizing nano-sized electrochemical active materials with a 3D porous framework constituted by conductive graphene sheets brings in enhanced lithium ion storage properties. Herein, a reduced graphene oxide (RGO) supported zinc ferrite (ZnFe2O4) composite anode material (ZnFe2O4/RGO) is fabricated by a simple and effective method. Firstly, redox reaction takes place between the oxygen-containing functional groups on few-layered graphene oxide (GO) sheets and controlled quantity of metallic Zn atoms. ZnO nanoparticles are in-situ nucleated and directly grow on GO sheets. Secondly, the GO sheets are completely reduced by abundant Fe atoms, and corresponding γ-Fe2O3 nanoparticles are formed neighboring the ZnO nanoparticles. In this step, 3D porous RGO supporting framework are constructed with γ-Fe2O3@ZnO nanoparticles effectively encapsulated between the RGO layers. Finally, the well-designed γ-Fe2O3@ZnO/RGO intermediate product undergoes a thermal treatment to allow a solid-state reaction and obtains the ZnFe2O4/RGO composite. At a high current rate of 1.0 A·g−1, the ZnFe2O4/RGO composite exhibits an inspiring reversible capacity of 1022 mAh·g−1 for 500 consecutive cycles as anode material for lithium ion batteries. And the insight into the attractive lithium storage performance has been studied in this work.

Highly Compressible and Sensitive Pressure Sensor under Large Strain Based on 3D Porous Reduced Graphene Oxide Fiber Fabrics in Wide Compression Strains.

The development of highly sensitive wearable and foldable pressure sensors is one of the central topics in artificial intelligence, human motion monitoring, and health care monitors. However, current pressure sensors with high sensitivity and good durability in low, medium, and high applied strains are rather limited. Herein, a flexible pressure sensor based on hierarchical three-dimensional and porous reduced graphene oxide (rGO) fiber fabrics as the key sensing element is presented. The internal conductive structural network is formed by the rGO fibers which are mutually contacted by interfused or noninterfused fiber-to-fiber interfaces. Thanks to the unique structures, the sensor can show an excellent sensitivity from low to high applied strains (0.24-70.0%), a high gauge factor (1668.48) at an applied compression of 66.0%, a good durability in a wide range of frequencies, a low detection limit (1.17 Pa), and anultrafast response time (30 ms). The dominated mechanism is that under compression, the slide of the graphene fibers through the polydimethylsiloxane matrix reduces the connection points between the fibers, causing a surge in electrical resistance. In addition, because graphene fibers are porous and defective, the change in geometry of the fibers also causes a change in the electrical resistance of the composite under compression. Furthermore, the interfused fiber-to-fiber interfaces can strengthen the mechanical stability under 0.01-1.0 Hz loadings and high applied strains, and the wrinkles on the surface of the rGO fibers increased the sensitivity under tiny loadings. In addition, the noninterfused fiber-to-fiber interfaces can produce a highly sensitive contact resistance, leading to a higher sensitivity at low applied strains.

Synthesis of SnO2/graphene composite anode materials for lithium-ion batteries

A tin dioxide/reduced graphene oxide composite (SnO2/RGO) is synthesized using combined methods, including in-situ metal tin reduction, spray drying and thermal treatment. Under mild hydrothermal condition, metal tin works as both reducing agent for few-layered graphene oxide (GO) to prepare restacked 2-dimensional (2D) reduced graphene oxide (RGO) sheets and metal source for homogeneously distributed nanostructured Sn and Sn oxides (Sn/SnO/SnO2). The 2D precursors are shrunk to a micro-sized dried blueberry shape via a spray drying process. After further thermal treatment, SnO2/RGO composite is obtained, in which Sn and SnO species are converted to SnO2 and the nano-sized SnO2 is well stabilized by the micro-sized 3D porous RGO supporting framework. The 3D SnO2/RGO composite exhibits not only a higher reversible capacity of 708 mAh·g−1 under a current density of 500 mA·g−1 over 150 cycles compared with 2D counterpart, but also a long and stable cycling life under a high current density of 1000 mA·g−1. This synthesis route can be considered as simple, economic and environmental-friendly, and it has great potential to find applications in other fields.

A novel strategy to boost the oxygen evolution reaction activity of NiFe-LDHs with in situ synthesized 3D porous reduced graphene oxide matrix as both the substrate and electronic carrier

NiFe-LDHs anchored on a 3D rGO matrix achieved a small overpotential and a relatively stable operating potential.

Three-dimensional porous scaffold by self-assembly of reduced graphene oxide and nano-hydroxyapatite composites for bone tissue engineering

Three-dimension (3D) porous reduced graphene oxide (RGO) scaffold has attracted increasing attention in bone tissue engineering due to its favorable osteoinductivity. In this paper, a 3D porous RGO composite was prepared from graphene oxide (GO) and nano-hydroxyapatite (nHA) via self-assembly, thus constructing biomimetic scaffold for bone defect reparation. Detailed studies were performed to evaluate its structure, cellular responses, biocompatibility and in vivo bone repair efficiency, emphasizing the influences of the composite on in vivo bone cell growth and mineralization. The as-prepared scaffold was found to significantly enhance the proliferation, alkaline phosphatase activity (ALP) and osteogenic gene expression of rat bone mesenchymal stem cells (rBMSCs). Further in vivo experiment demonstrated that the circular calvarial defects with 4 mm diameter in rabbit were successfully healed by 20% nHA incorporated RGO (nHA@RGO) porous scaffold after 6 weeks implanting, which was visibly quicker than the RGO one. The computed tomography (CT) and histological analysis showed the improved collagen deposition, cell proliferation and new bone formation occurred in the 20% nHA@RGO treated group. These results indicated that the as-prepared porous scaffold has a promising capacity to stimulate mineralization and promote the in vivo defect healing.

Nano ZnO enhanced 3D porous reduced graphene oxide (RGO) for light-weight superior electromagnetic interference shielding

Nano ZnO enhanced 3D porous reduced graphene oxide (RGO) with superior electromagnetic interferece (EMI) shielding efficiency (SE) was fabricated through a UV enhanced hydrothermal process. In this study, a composite with 10 wt% of 3D-RGO/ZnO was tested in a broadband frequency range from 2 to 18 GHz. Under the whole test conditions, the ratio of SEA/SET is higher than 50% and the maximum value can reach to 94%, indicating the shielding mechanism mainly attributes to absorption. The EMI SE showed that the thinnest thicknesses to shield different frequency range are 0.7 mm for 10 dB, 1.6 mm for 20 dB and 3.7 mm for 30 dB, which suggests 3D-RGO/ZnO could meet the requirement of new generate EMI shielding material.

3D Freeze-Casting of Cellular Graphene Films for Ultrahigh-Power-Density Supercapacitors.

3D cellular graphene films with open porosity, high electrical conductivity, and good tensile strength, can be synthesized by a method combining freeze-casting and filtration. The resulting supercapacitors based on 3D porous reduced graphene oxide (RGO) film exhibit extremely high specific power densities and high energy densities. The fabrication process provides an effective means for controlling the pore size, electronic conductivity, and loading mass of the electrode materials, toward devices with high energy-storage performance.