3D Reduced Graphene Oxide Aerogel Research Articles

VO2/VS4 heterostructures structure–modified 3D reduced graphene oxide aerogel as an advanced host for lithium–sulfur batteries

Lithium–sulfur batteries face challenges including volume expansion, slow reaction kinetics, and shuttle effects. To overcome these limitations, we utilized a combination of vanadium–based heterostructures and conductive porous reduced graphene oxide aerogels to improve charge transfer kinetics. The researchers synthesised vanadium–based reduced graphene oxide aerogels (VO2/VS4@RGO) via tube furnace calcination and a one–step hydrothermal method. Vanadium–based heterostructures were electrostatically adsorbed onto the surface of three–dimensional reduced graphene oxide aerogels. The fibrous structure of VO2/VS4 promoted charge transfer, while the high conductivity of VS bonds lowered the surface reaction barrier. The VO2/VS4@RGO–3/S cathode exhibited outstanding cycling stability at a high discharge rate of 2C, demonstrating an initial discharge specific capacity of 771.94 mAh g−1 and an average decay rate of 0.071 % after 700 cycles. It also maintained excellent electrochemical performance under high sulfur loading.

Highly efficient removal of ionic dyes in aqueous solutions using magnetic 3D reduced graphene oxide aerogel supported nano zero-valent iron

This study aims to develop three-dimension reduced graphene oxide aerogel supported nano zero-valent iron (rGOA-nZVI) by hydrothermal and liquid phase reduction approach and applies it to the removal of two typical dyes, methylene blue (MB) and methyl orange (MO) from aqueous solutions. The obtained magnetic rGOA-nZVI composites were characterized by scanning electron microscopy (SEM), atomic force microscopy, Brunauer-Emmett-Teller, X-ray diffraction and Fourier transform infrared spectroscopy, and its removal efficiencies for MB and MO from aqueous solutions were evaluated. The removal processes of MB and MO could be completed within 30 min, which were well described by the pseudo-second order kinetic model. The rGOA-nZVI nanocomposites exhibited remarkable performance for the removal of MB (the maximum adsorption amount, <i>q</i><sub>max</sub> = 3918 mg/g) and MO (<i>q</i><sub>max</sub> = 667 mg/g) in a wide pH range (pH 1.0-10.0). Furthermore, rGOA-nZVI is stable and recyclable with high dye removal efficiencies (> 90%) after five cycles. The removal mechanisms were demonstrated with SEM and XRD analyses before and after MB and MO removal. This study showed that rGOA acts as an excellent carrier for nZVI, and the rGOA-nZVI nanocomposites are efficient materials for the advanced treatment of dye wastewater over a wide pH range.

Revealing Nanodomain Structures of Bottom-Up-Fabricated Graphene-Embedded Silicon Oxycarbide Ceramics.

Dispersing graphene nanosheets in polymer-derived ceramics (PDCs) has become a promising route to produce exceptional mechanical and functional properties. To reveal the complex nanodomain structures of graphene–PDC composites, a novel reduced graphene oxide aerogel embedded silicon oxycarbide (RGOA-SiOC) nanocomposite was fabricated bottom-up using a 3D reduced graphene oxide aerogel as a skeleton followed by infiltration of a ceramic precursor and high-temperature pyrolysis. The reduced graphene oxide played a critical role in not only the form of the free carbon phase but also the distribution of SiOxC4−x structural units in SiOC. Long-ordered and continuous graphene layers were then embedded into the amorphous SiOC phase. The oxygen-rich SiOxC4−x units were more prone to forming than carbon-rich SiOxC4−x units in SiOC after the introduction of reduced graphene oxide, which we attributed to the bonding of Si atoms in SiOC with O atoms in reduced graphene oxide during the pyrolysis process.

Dispersive solid phase extraction of ginkgolide B from real samples using 3D reduced oxide graphene aerogel based molecularly imprinted polymers

AbstractIn this article, novel molecularly imprinted polymers based on 3D reduced graphene oxide aerogel (3D RGO‐GBMIPs) were successfully fabricated and applied as adsorbents for dispersed solid‐phase extraction (DSPE) of ginkgolide B (GB). After being prepared by surface molecular imprinted technology, 3D RGO‐GBMIPs were successively characterized by fourier transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, and scanning electron microscope. The results of adsorption experiments revealed that 3D RGO‐GBMIPs presented highly selective recognition properties and well reusability. The main variables influencing DSPE efficiency, including extraction solvent, 3D RGO‐GBMIPs dosage, category, and volume of eluent, as well as elution time were investigated. The DSPE results showed that 3D RGO‐GBMIPs had an obvious effect on the improvement of GB purity in ginkgo biloba extract, with a satisfactory recovery rate and yield. Therefore, 3D RGO‐GBMIPs are expected to be applied for the enrichment of GB from complex matrices.

Highly stable potentiometric sensor with reduced graphene oxide aerogel as a solid contact for detection of nitrate and calcium ions

• 3D reduced graphene oxide aerogel (rGOA) was synthesised through self-assembly of graphene oxide via heat treatment. • The sensor exhibited outstanding response, due to the large surface area and excellent electrical conductivity of rGOA. • Long-term stability of the sensor improved owing to the hydrophobicity of rGOA. • NO 3 – and Ca 2+ were detected in perilla leaves using the proposed sensor, and this result was in good agreement with the ICP and IC analysis results. Numerous reports have elucidated the importance of detecting of NO 3 − and Ca 2+ ions for monitoring their levels to optimize crop growth. Herein, we prepared a reduced graphene oxide aerogel (rGOA) as a promising solid-contact material for manufacturing a highly stable solid contact ion-selective electrode (SC-ISE) for monitoring to NO 3 − and Ca 2+ . The rGOA was synthesized through self-assembly of graphene oxide via heat treatment. Cyclic voltammetry and chronopotentilmetry were employed to demonstrate the fast charge transfer and large double layer capacitance of the rGOA layer modified electrode. The sensor comprising rGOA exhibited excellent Nernstian responses (59.1 mV/log [NO 3 − ] and 28.4 mV/log [Ca 2+ ]) and ion detection limits (759 nM for NO 3 − and 186 nM for Ca 2+ ) due to its outstanding electrical conductivity and large surface area of rGOA. The Ag/AgCl electrode with a polyvinyl butyral (PVB) film was used as the reference electrode. Water layer tests and potentiometry confirmed that the long-term stability of the electrode improved owing to the hydrophobicity of rGOA. Furthermore NO 3 − and Ca 2+ ions were detected in perilla leaf using the proposed ion-selective sensor, which was in agreement with the results of ion chromatography and inductively coupled plasma analyses. Thus, the proposed sensor provides an excellent sensing platform for the detection of inorganic ions in plant sap.

3D reduced graphene oxide aerogel supported TiO2-x for shape-stable phase change composites with high photothermal efficiency and thermal conductivity

Photothermal conversion, thermal energy transportation and storage are crucial in solar energy utilization. Due to the complexity of synthesis technology, it remains a hot issue to achieve the integration of high photothermal conversion, thermal conductivity and energy storage for phase change materials (PCMs) in recent years. As a typical carbon aerogel, reduced graphene oxide (RGO) aerogel exhibits the porous structure and outstanding properties, which makes RGO aerogel an attractive material for compounding with phase change materials. In this work, RGO aerogel is prepared by the hydrothermal-freeze drying method, which can effectively solve the issue of PCMs leakage. Oxygen-deficient TiO2 (TiO2-x) can further enhance the optical performance and improve the thermal conductivity of composite materials to 1.22 W/(m·K). The optimum TiO2-x content is 80%, which can obtain 89.9% photothermal conversion efficiency for TiO2-x/RGO@PW. TiO2-x/RGO aerogel will bring a new paradigm for PCMs as the working medium in absorption solar energy.

Highly Sensitive and Flexible Piezoresistive Pressure Sensors Based on 3D Reduced Graphene Oxide Aerogel

The flexible piezoresistive sensors have versatile applications for healthcare. The fabrication procedures of these sensors are generally costly, complex, and environmentally unfriendly. Herein, we use L-cystine as the green reductant and templating agent to prepare 3D reduced graphene oxide (rGO) aerogel, and polyvinyl chloride tape as the substrates to encapsulate the aerogel for making the piezoresistive sensor. The sensor shows good linearity of resistance to logarithmic pressure value in a wide range of 170.4 kPa to 2.4 MPa, and it is capable to monitor the wrist pulse and human motion. Sensors fabricated by this facile and economical method have great potential application in electronic skin.

Hybrid Capacitors: Mesoporous Thorn‐Covered Core–Shell Cathode and 3D Reduced Graphene Oxide Aerogel Composite Anode with Conductive Multivalence Metal Sulfides for High‐Performance Aqueous Hybrid Capacitors (Adv. Energy Mater. 12/2021)

In article number 2003563, Jeung Ku Kang and co-workers describe aqueous hybrid capacitors assembled via a mesoporous thorn-covered core–shell cathode and a 3D reduced graphene oxide aerogel composite anode. The aqueous capacitors achieve a high energy density up to 125 Wh kg−1, ≈100% Coulombic efficiency over 50 000 cycles, and ultrahigh power density up to 23 998 W kg−1 allowing ultrafast recharge within a minute.

Mesoporous Thorn‐Covered Core–Shell Cathode and 3D Reduced Graphene Oxide Aerogel Composite Anode with Conductive Multivalence Metal Sulfides for High‐Performance Aqueous Hybrid Capacitors

AbstractAqueous hybrid capacitors (AHCs) are very promising electrochemical energy devices due to their being safe, cheap, and environmentally friendly, but their low energy and power densities are yet to be overcome for prolonged operation in a single fast charging device. Herein, a strategy to realize high‐energy density and ultrafast rechargeable AHCs is reported. A thorn‐covered core–shell conductive multivalence metal sulfide is synthesized as a cathode material that achieves high capacity via multivalence Ni and Co states and contains multiple mesoporous channels for fast ion transfer and ultrafine nanoparticles for efficient contact with electrolyte ions. Moreover, the multivalence metal states of the Fe1−xS anode units loaded on a three‐dimensional carbon structure with the mesoporous holes attain high capacity even at a very fast charging rate (20 A g−1, ≈86.4 C rate). The proposed AHC exploits the advantages of capacitive and diffusion‐controlled reactions. This is demonstrated by its high‐energy density (up to 120.5 Wh kg−1) surpassing that of state‐of‐the‐art AHCs and the ultrafast rechargeable power density (up to 23,998 W kg−1) that exceeds those of battery‐type reactions more than 100‐fold and provides long‐life stability for over 50 000 charge–discharge cycles.

Selective adsorption of cesium (I) from water by Prussian blue analogues anchored on 3D reduced graphene oxide aerogel

In this paper, Prussian blue analogues (PBAs) anchored on 3D reduced graphene aerogel (denoted as 3D rGO/PBAs) was prepared, characterized and applied for adsorption of Cs(I) from aqueous solution. The results showed that 3D rGO/PBAs had high specific surface and good hydrophilic property, which was beneficial to the exposure of adsorptive sites and the transfer of adsorbates. The composite exhibited excellent adsorption performance towards Cs(I), and the maximum adsorption capacity was up to 204.9 mg/g, higher than most of reported values. The pseudo second-order kinetic model (R2 = 0.999) and the Langmuir isotherm model (R2 = 0.997) could fit the adsorption process well, suggesting the nature of homogeneous monolayer chemisorption. High distribution coefficients (kd) (2.8 × 104 to 5.8 × 104 mL/g), revealed that the composite had good selectivity. Ion-exchange, ion trapping and the complexation interaction might be involved in the process of cesium adsorption, in which ion-exchange may be dominant by characterization results.

Self-powered supercapacitor-mode tactile sensor based on polygonal litchi–like nanospheres decorated three-dimensional reduced graphene oxide aerogel for wearable electronics device

Rapidly growing improvement of portable and wearable devices stimulates requirements for multifunction tactile electronics. Herein, we report a novel electrochemical-driving supercapacitor-mode self-powered tactile sensor based on polygonal litchi–like nanospheres embedded 3D reduced graphene oxide aerogel framework, which displays outstanding compressibility to accommodate complex external conditions such as large-scale mechanical deformations. The sensor has the power to realize function of both strain compression sensing and energy storage capabilities simultaneously. The porosity of aerogels and pseudocapacitance property of polygonal litchi–like CoV2O6 nanospheres endows the composite aerogel with superior electrochemical performance with energy density of 139.18 Wh kg−1 at 500.0 W kg−1. Taking advantage of splendid elasticity of aerogel structure, self-powered supercapacitor-mode sensor response to external pressure signal sensitively. The self-powered sensor not only presents promising potentials in wireless charging system, but also expands the practical application areas of electrochemical energy storage device greatly.

Size-tunable SnO2/Co2SnO4 nanoparticles loaded 3D reduced graphene oxide aerogel architecture as anodes for high performance lithium ion batteries

The size control of active materials among porous carbon architecture remains crucial for the performance of “guest/substrate” nanohybrids anodes among lithium ion batteries. Herein, we prove that graphene oxide (GO) substrate plays an important role on the size control of active materials and put forward a new strategy to controllably adjust oxides particle size on the 3D reduced graphene oxide aerogel (rGOA) structure. Specifically, the active functional groups on GO substrates can be modulated by controlling the gelation degree of GO, which can then realize an in-situ regulation of the active materials growth process due to Ostwald ripening, and the particle size of them are reduced distinctly. The obtained small-size and fine SnO2/Co2SnO4 loaded rGOA architecture (SnO2/Co2SnO4@rGOA-10) shows improved electrochemical performance, where 3D rGOA structure with large numbers of open pores can not only facilitate charge transfer process but also provide unblocked channels for electrolyte transportation. The decrease of nanoparticles size can also shorten ion transfer route within the bulk phase so as to alleviate the volume expansion as well as improve the kinetics of Li+/e− transfer process. The rational strategy of modulating the gelation degree of GO substrates can be extended to synthesize other tunable “guest/substrate” functional nanohybrids.

Graphene-based materials with different morphologies and structures as interlayers for high-performance lithium-sulfur batteries

Lithium-sulfur batteries have attracted much attention for energy storage. However, the shuttle effect causes the poor cycling performance. In this study, we applied a carbon-based interlayer to trap polysulfide to reduce shuttle effect. The carbon-based materials including 3D reduced graphene oxide aerogel, 3D N-doped reduced graphene oxide aerogel, and 2D reduced graphene oxide. The materials were coated on one side of carboxylate-modified carbon fiber paper. The effect of the assemble direction of the coated materials facing in and out of the cathode were investigated. The results showed that the interlayer with 3D N-doped reduced graphene oxide aerogel exhibits superior performance and stability. In addition, the coated material placed face-to-face the cathode can improve the battery performance as compared to another direction.

3D reduced graphene oxide aerogel-mediated Z-scheme photocatalytic system for highly efficient solar-driven water oxidation and removal of antibiotics

The construction of natural photosynthesis-inspired Z-scheme tandem system has been considered as a promising strategy to fulfill efficient electron-hole separation and charge transportation in composite photocatalysts, providing a unique opportunity to achieve improved solar-driven photocatalytic water splitting performance superior to conventional heterojunctions. The presence of an ideal electron mediator is critical to promote effective electron transfer in Z-scheme semiconductor photocatalytic systems. Herein, for the first time, we report the fabrication of CeVO4/three-dimensional (3D) reduced graphene oxide (RGO) aerogel/BiVO4 ternary composites and their use as photocatalysts for visible-light-driven water oxidation and tetracycline (TC) degradation. As-prepared hybrid materials exhibit well-organized heterostructures where two vanadates with different dimensional features are surrounded by 3D aerogel networks. Under visible light irradiation, the optimal composite material revealed highly improved photocatalytic activity both in oxygen evolution from water splitting and TC degradation. The enhancement in photocatalytic efficiency is assumed to come from illuminated Z-scheme CeVO4/3D RGO/BiVO4 configuration, in which conductive 3D RGO aerogel functions as an effective electron mediator and builds the bridge between two vanadates, offering a tandem channel for more efficient charge transfer in two semiconductors. This work may provide a new clue for the design of all-solid-state Z-scheme composite photocatalytic materials in energy and environmental applications.

Dual-phase spinel Li4Ti5O12/anatase TiO2 nanosheet anchored 3D reduced graphene oxide aerogel scaffolds as self-supporting electrodes for high-performance Na- and Li-ion batteries

Self-supporting LTO-AT/RGO composite as anode materiel was prepared via a facile hetero-assembly, freeze-drying, mechanical compression and annealing. They exhibit excellent electrochemical capability when used for LIBs and SIBs.

Electrocatalytic oxidation of ethylene glycol on palladium coated on 3D reduced graphene oxide aerogel paper in alkali media: Effects of carbon supports and hydrodynamic diffusion

To enhance Pd electro-catalysts in their electro-catalytic activity for C-C bond breaking and tolerance stability, Pd was electrodeposited on high-porosity 3D reduced graphene oxide (rGO) aerogel paper. For comparison, the Pd was also coated on other three different carbon material surfaces: bare carbon fiber paper (CFP), and CFP modified with either 2D graphene oxide (GO) and 2D rGO nanosheets. The Pd/3D rGO aerogel paper exhibits higher catalytic activity toward the electro-oxidation of ethylene glycol in alkaline media and higher excellent tolerance stability than other electrodes due to ultra-high porosity of the 3D rGO support leading to high active electrochemical surface area of the as-fabricated Pd catalyst electrode. In addition, the hydrodynamic diffusion of ethylene glycol to the cayalyst surface investigated in this work plays a major role to the catalytic activity of the as-prepared electrocatalyst. The Pd/3D rGO aerogel rotating disk electrode exhibits a high anodic current density of 267.8mAcm−2 at 3000rpm. This high-performance Pd/3D rGO aerogel may be practically used as the high-efficiency anode of direct ethylene glycol and other related alcohol fuel cells.