Three-dimensional Graphene Aerogel Research Articles

Preparation and electromagnetic wave absorption of compressible graphene aerogels

In this study, a developed easy-operation method was adopted to generate ultralight and compressible graphene aerogels by using graphene oxide and ammonia. By changing the process parameters, such as reduction temperature, reducing agent content and ammonia concentration, the variation laws of the density and pore size of aerogels were obtained, which aided in realizing the controllable preparation of aerogel structures. The prepared graphene aerogel has good compressive performance, and its density can reach 5.26 mg/cm3. Although it was repeatedly compressed 200 times under a load that was 4000 times as large as its own weight, it maintained its structural integrity and mechanical properties. An ideal model of three-dimensional graphene aerogel was constructed, and the electromagnetic wave absorption performance was simulated using the Computer Simulation Technology (CST) Microwave Studio software. The results showed that when the thickness, pore size and height of the sheet were 1.4, 5 and 14 mm, respectively, an optimal electromagnetic wave absorption effect of −31.08 dB could be obtained. Furthermore, the effects of thickness, pore size and height of the sheet on the electromagnetic wave absorption performance are revealed, which provide a reference for the structural design of aerogels with both compressibility and electromagnetic wave absorption performance.

Graphene aerogel based positive electrode for lithium ion batteries

In this study, a composite of LiNi0.8Mn0.1Co0.1O2 nanoparticles (nNMC-811) supported by three-dimensional (3D) graphene aerogel (GA) was prepared to increase the practical energy density and performance capability of high nickel cathodes. The porous LiNi0.8Mn0.1Co0.1O2 nanoparticle/graphene aerogel (nNMC-811/GA) composite is composed of nNMC-811 and graphene that act as a bridge for electron transfer and acceleration of lithium ion diffusion. nNMC-811 and nNMC-811/GA cathodes characterization data with techniques including X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS) are discussed. Both Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) made clear observations of the uniform distribution of the cathode active powders over the 3D graphene aerogel structure. The electrochemical performance of the nNMC-811 and nNMC-811/GA cathodes was evaluated by the galvanostatic charge-discharge measurement between 2.5 V and 4.5 V at room temperature using a computer-controlled battery tester. In addition, variable speed capacity ratios (C-rate), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) analyzes were also performed. nNMC-811/GA hybrid composite structure delivers a specific capacity of 183.15 mAhg−1 at C/2 after the 500th cycle. It is understood from the FE-SEM images taken after the cycle that there is no deterioration in the structure. According to results, it was observed that the 3D porous structure of the nNMC-811/GA composite facilitated the mobility of Li+ ions, and the excellent electrochemical performances of the cathodes were improved due to the increasing defects as well as the electrical conductivity of GA.

A three-dimensional hierarchical porous graphene aerogel as a fiber coating for headspace solid-phase microextraction: Enhancing the enrichment and detection of polychlorinated naphthalenes in fish

In this study, a novel three-dimensional hierarchical porous deep eutectic solvents-modified graphene aerogel (3D DES-GA) was synthesized for use as a solid-phase microextraction (SPME) fiber coating. The SPME fiber was characterized by its fluffy and hierarchical porous structure, uniform thickness, and rapid mass transfer capabilities. This fiber demonstrated a lifetime (≥160 uses) and excellent precision (with relative standard deviations of 2.4–6.6% for single fiber and 6.0–9.8% for fiber-to-fiber repeatability). The SPME fiber also exhibited remarkable extraction performance for polycyclic aromatic hydrocarbons and polychlorinated biphenyls, which are common persistent organic pollutants in environmental samples. When combined with gas chromatography-tandem mass spectrometry, the method allowed for high-efficiency extraction (enrichment factors ranging from 1225 to 4652 folds) and sensitive determination (limit of detection ranging from 0.010 to 0.056 pg g−1) of polychlorinated naphthalenes (PCNs) in complex samples. To validate this method, we applied it to the determination of four PCNs in five types of fish tissues. The results revealed the presence of 1-chloronaphthalene at concentrations of 7.0 ± 2.9–34.8 ± 2.1 pg g−1 and 1,4-dichloronaphthalene at concentrations of 6.0 ± 0.3–10.9 ± 1.4 pg g−1 in three fish species. Compared with reported sample pretreatment methods reported in the literature, this proposed headspace SPME method offers additional advantages, including simplicity of operation and reduced sample and organic solvent consumption.

Electron-interactive 1D porous vertical NiCo2O4 nanowire and 3D N-doped graphene aerogel enable high hydroxyl-ion adsorption capacity for superior energy storage

Supercapacitors are a kind of highly efficient energy-storage device with long cycle life and high power density, however, their specific capacitance is insufficient for further application and development. In this work, a novel composite with one-dimensional (1D) NiCo2O4 nanowire arrays (NiCo2O4-NWA) vertically supported on three-dimensional (3D) nitrogen-doped graphene aerogel (NGA) is designed and facilely realized by hydrothermal reaction and thermal treatment. The NiCo2O4 nanowires, with length of ∼1 μm and diameter of ∼25 nm, display a porous structure and are regularly arranged on both sides of the sheets in nitrogen-doped graphene aerogel. The aerogel-supporting NiCo2O4 nanowires demonstrate a remarkably high specific capacitance of 2742 F g−1 at 1 A g−1, and an outstanding cyclic stability with capacitance retention of 90% even after 10,000 cycles at 80 A g−1. The density functional theory calculation shows the narrow band gap (0.32 eV) and strong electronic interaction and hydroxyl-ion adsorption effect of NiCo2O4 supported on NGA, resulting in superior specific capacitance and energy storage performance. The 3D nitrogen-doped graphene aerogel supporting 1D nanowire arrays represent a promising high-performance electrode material for application in the supercapacitors and other electrochemical energy-conversion and storage equipment.

Materials space-tectonics methodology of conductive mesoporous carbon nanohorns embedded graphene aerogels anchoring Pd nanocrystalline for an efficient ethanol oxidation reaction

Materials space-tectonics (MST) methodology is a powerful strategy to design catalytic materials synthesis to overcome the limitation of monotonous pore geometries and develop functional structures with surface-specific functions. Based on the MST, herein, carbon nanohorns (CNH) as “spacers” inserted into three-dimensional (3D) nitrogen-doped graphene aerogel (NG) anchoring Pd nanocrystalline (Pd/CNH@NG) was constructed through a facile hydrothermal approach and wet chemical reduction method without surfactant and employed as electrocatalyst for ethanol oxidation reaction (EOR). The introduction of CNH can provide important mesopore and macropore characters and generate more active sites to anchor Pd nanocrystalline on the basis of unique internal and interstitial nanopore structures, high surface area and conductive graphitic structure, then enhancing the electrocatalytic efficiency, stability and poison tolerance of catalysts. Meanwhile, the role of CNH doped NG also includes accelerating the reaction of the intermediate (CH3COads) manufactured on the Pd-based aerogels surface with adsorbed hydroxyl (OHads) due to coordination effect from Pyridinic-nitrogen and pyrrolic-nitrogen species. The electrochemical results reveal that the specific and mass activities of the obtained Pd/CNH@NG-2 aerogel (the mass ratio of graphene oxide and CNH is 1:3) are 1.38 and 2.86 times higher than those of the commercial Pd/C for EOR. Simultaneously, the current density of Pd/CNH@NG-2 still maintains 70 % after 500 cycles of complete CV, but commercial Pd/C only maintains 22.6 % of the initial activity. The synthesis of Pd/CNH@NG not only offers a porous three-dimensional aerogel for the EOR but also optimizes a facile strategy to fabricate superior supports for promoting the commercialization of DEFCs.

Alternating current assisted preparation of three-dimensional graphene aerogels and the application in electromagnetic interference shielding

Three-dimensional (3D) graphene aerogels (GA) have obtained significant attention across various fields due to their lightweight and porous properties. Nevertheless, the development of a scalable and environmentally friendly method for synthesizing self-supported 3D GA remains a challenge. In this study, we introduced an innovative method for the preparation of 3D GA using alternating current (AC) strategy, which fully used the characteristic of AC's constantly changing current direction to attract graphene oxide (GO) particles to the electrode surface and subsequently reduced them to reduced GO (rGO). Ultimately, GA is self-assembled on the electrode surface under repeated cycles. An applied AC signal with optimal parameters produced a porous GA with an oxygen content of 10.76 at%, which is 66.67% less than that of the original GO. When applying GA to electromagnetic interference (EMI) shielding, it provides a maximum specific shielding effectiveness of 9100 dB cm2 g−1 at X-band due to the repeated reflection and absorption of electromagnetic waves (EMWs) by the abundant pore wall. Furthermore, the shielding effectiveness can be significantly improved to 68.60 dB at the X-band for a multilayer GA. Notably, it is worth emphasizing that this AC-assisted synthesis method has proven its adaptability to various metal electrodes, such as cost-effective iron and copper. Importantly, this method avoids the high-temperature treatments and the use of environmentally hazardous chemicals. It is envisaged that this environmentally friendly and low-cost approach will greatly facilitate the cost-effective production of 3D GA with diverse applications.

Construction of novel stable surface ion-imprinted graphene aerogels for efficient and selective extraction of lithium ion

Selective extraction of lithium from salt lake brine has attracted widespread attention in order to meet the growing global demand for lithium. Due to the high Mg2+/Li+ ratio and low Li+ concentration in salt lake brine, extracting Li+ from salt lake brine is extremely challenging. Herein, a novel approach was employed using graphene oxide (GO) with abundant functional groups as the skeleton material, and trihydroxymethyl aminomethane (Tris) as the pioneering reducing agent. Through the liquid phase self-assembly technology combined with surface modification, the Li+ imprinted three-dimensional block graphene aerogels (IDGAs) were successfully constructed under the assisted cross-linking effect of N,N-dimethylformamide (DMF). The IDGAs achieve good adsorption capacity (12.55 mg g−1), excellent regeneration performance, and comparatively high selectivity against Na+, K+, and Mg2+ of 4.75, 2.71, and 1.90, respectively. The exceptional properties of IDGAs can be attributed to the synergism resulting from the establishment of adsorption sites through the high specific surface area of the skeleton, as well as the selective recognition of Li+ by 2-hydroxymethyl-12-crown ether-4. Consequently, IDGAs represent a highly promising option for the efficient extraction of lithium from salt lake brine.

Analysis of Polycyclic Aromatic Hydrocarbons Using Magnetic Three-Dimensional Graphene Solid-Phase Extraction Coupled with Gas Chromatography–Mass Spectrometry

In this study, a composite material consisting of three-dimensional graphene aerogel and iron oxide nanoparticles (3DG/Fe3O4) was created and utilized for the purpose of magnetic solid-phase extraction (MSPE) of thirteen polycyclic aromatic hydrocarbon (PAH) compounds via gas chromatography–mass spectrometry/selected ion monitoring (GC-MS/SIM) analysis. The synthesized adsorbent underwent a range of characterization techniques, including scanning electron microscopy, vibrating sample magnetometry, Raman spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, Fourier transform-infrared spectroscopy, and Barrett–Joyner–Halenda techniques, to examine its properties and morphology. The synthesized adsorbent integrates the benefits of superior adsorption capacity from modified graphene oxide (GO) with the magnetic separability of magnetite microparticles, resulting in a high adsorption capacity with easy separation from sample solutions. The efficiency of the proposed method was optimized and modeled using a central composite design (CCD), which considered the primary factors influencing it. The optimal conditions were obtained as the adsorbent dosage of 10 mg, the extraction time of 4 min, and the salt concentration of 3% w/v. The limit of detection for the target PAHs was established to range from 0.016 to 0.2 ng mL−1 in optimal conditions, exhibiting a signal-to-noise ratio of 3. The linear dynamic range spanned from 5 to 100 ng mL−1, with determination coefficients (R2) ranging from 0.9913 to 0.9997. The intra- and inter-day precisions were calculated as relative standard deviations (RSDs) equal to 3.9% and 4.7%, respectively. The proposed method was successfully applied to the determination of PAHs in water samples (tap, river, and rainwater), and recoveries in the range of 71–110% (RSDs < 5.2%, n = 3) were obtained.

Three-dimensional graphene aerogel mitigated the toxic impact of chloramphenicol wastewater on microorganisms in an EGSB reactor

Anaerobic treatment of chloramphenicol wastewater holds significant promise due to its potential for bioenergy generation. However, the high concentration of organic matter and residual toxic substances in the wastewater severely inhibit the activity of microorganisms. In this study, a three-dimensional graphene aerogel (GA), as a conductive material with high specific surface area (114.942 m2 g−1) and pore volume (0.352 cm3 g−1), was synthesized and its role in the efficiency and related mechanism for EGSB reactor to treat chloramphenicol wastewater was verified. The results indicated that synergy effects of GA for Chemical Oxygen Demand (COD) removal (increased by 8.17 %), chloramphenicol (CAP) removal (increased by 4.43 %) and methane production (increased by 70.29 %). Furthermore, GA increased the average particle size of anaerobic granular sludge (AGS) and promoted AGS to secrete more redox active substances. Microbial community analysis revealed that GA increased the relative abundance of functional bacteria and archaea, specifically Syntrophomonas, Geobacter, Methanothrix, and Methanolinea. These microbial species can participate in direct interspecific electron transfer (DIET). This research serves as a theoretical foundation for the application of GA in mitigating the toxic impact of refractory organic substances, such as antibiotics, on microorganisms during anaerobic treatment processes.

N-Octadecane Encapsulated by Assembled BN/GO Aerogels for Highly Improved Thermal Conductivity and Energy Storage Capacity.

The rapid development of industry has emphasized the importance of phase change materials (PCMs) with a high latent-heat storage capacity and good thermal stability in promoting sustainable energy solutions. However, the inherent low thermal conductivity and poor thermal-cycling stability of PCMs limit their application. In this study, we constructed three-dimensional (3D) hybrid graphene aerogels (GBA) based on synergistic assembly and cross-linking between GO and modified hexagonal boron nitride (h-BN). Highly thermally conductive GBA was utilized as the supporting optimal matrix for encapsulating OD, and further implied that composite matrix n-octadecane (OD)/GBA composite PCMs were further prepared by encapsulating OD within the GBA structure. Due to the highly thermally conductive network of GBA, the latent heat of the composite PCMs improved to 208.3 J/g, with negligible changes after 100 thermal cycles. In addition, the thermal conductivity of the composite PCMs was significantly enhanced to 1.444 W/(m·k), increasing by 738% compared to OD. These results sufficiently confirmed that the novel GBA with a well-defined porous structure served as PCMs with excellent comprehensive performance offer great potential for thermal energy storage applications.

Hierarchical three-dimensional ZnCo2O4/graphene aerogel composite for excellent stability at large current density in lithium-ion battery

Exploiting lithium-ion batteries (LIBs) with high reversible capacity and excellent durability at large current density is recognized as a promising strategy for energy storage. In this work, the ZnCo2O4/graphene aerogel (ZnCo2O4/GA) composite was fabricated through a facile hydrothermal process and evaluated as the anode in lithium-ion batteries. Due to the excellent conductivity of graphene, the ZnCo2O4/GA and ZnCo2O4/reduced graphene oxide (ZnCo2O4/rGO) endow superior specific capacity and durability than pure ZnCo2O4. More importantly, ZnCo2O4 cubes were confined geometrically into a three-dimensional (3D) graphene aerogel structure in the composite, which is beneficial to accommodate the volume change and enhances the mechanical strength of composites. Thus, ZnCo2O4/GA exhibits superior durability than ZnCo2O4/rGO at 1 A g-1. This work confirms the essential effect and directly reveals the merit of 3D framework structure for enhancing the performance of LIBs at the high current density, and provides a feasible strategy to design advanced electrodes for energy conversion.

Three-Dimensional Graphene Aerogel Supported on Efficient Anode Electrocatalyst for Methanol Electrooxidation in Acid Media

This work attempted to improve the catalytic performance of an anodic catalyst for use in direct methanol fuel cells by coating graphene aerogel (GA) with platinum nanoparticles. A hydrothermal, freeze-drying, and microwave reduction method were used to load Pt–Ru bimetallic nanoparticles onto a graphene aerogel. The mesoporous structure of a graphene aerogel is expected to enhance the mass transfer in an electrode. XRD, Raman spectroscopy, SEM, and TEM described the as-synthesized PtRu/GA. Compared to commercial PtRu/C with the same loading (20%), the electrocatalytic performance of PtRu/GA presents superior stability in the methanol oxidation reaction. Furthermore, PtRu/GA offers an electrochemical surface area of 38.49 m2g−1, with a maximal mass activity/specific activity towards methanol oxidation of 219.78 mAmg−1/0.287 mAcm−2, which is higher than that of commercial PtRu/C, 73.11 mAmg−1/0.187 mAcm−2. Thus, the enhanced electrocatalytic performance of PtRu/GA for methanol oxidation proved that GA has excellent potential to improve the performance of Pt catalysts and tolerance towards CO poisoning.

SiC Nanowires Bridged Graphene Aerogels with a Vertically Aligned Structure for Highly Thermal Conductive Epoxy Resin Composites and Their Mechanism

Thermal conductive composites have a wide application in the electronic packaging field, and fabricating three-dimensional (3D) graphene aerogels by the self-assembly method is a facile way to construct thermal conductive networks in polymer composites. But those self-assembled graphene aerogels can only endow composites with a limited thermal conductivity because (1) abundant defects on RGO sheets reduce their intrinsic thermal conductivity and (2) massive edges and gaps in aerogels cause severe phonon scattering. Many works before have been done to heal the defects by high-temperature annealing, but the works of filling gaps and decreasing phonon scattering are rare. Herein, we designed a facile route to synthesize SiC nanowires on the edges of RGO sheets for connecting adjacent RGO sheets, decreasing phonon scattering, and enhancing thermal conduction efficiency in graphene aerogels. Before that, RGO/Si aerogels with vertically aligned structures were obtained by the chemical reduction method and the freeze-drying method to enhance their through-plane thermal conduction efficiency. When the initial mass ratio of GO solute/silicon powder was 5:1, HGA-5 endowed the EP composite with a high through-plane thermal conductivity of 3.59 W m–1 K–1 at a relatively low filler loading of 2.87 wt %. Finite element analysis was applied to illustrate the thermal conductive mechanism of the hybrid aerogels-filled EP composites. The EMI shielding performance of the composites was also discussed in this work.

Cobalt-Free Layered LiNi0.8Mn0.15Al0.05O2/Graphene Aerogel Composite Electrode for Next-Generation Li-Ion Batteries.

In this work, we introduce LiNi0.8Mn0.15Al0.05O2 (NMA), which is cobalt-free and has a high nickel content, and a conductive composite material to NMA by supporting it with a three-dimensional (3D) graphene aerogel (GA). With an easy freeze-drying approach, NMA nanoparticles are properly dispersed on graphene sheets, and GA creates a strong and conductive framework, significantly improving the structure and conductivity. The structure of the pure NMA and NMA/graphene aerogel (NMA/GA) composite was investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). XRD and FE-SEM analyses clearly indicated that ultrapure NMA structures are homogeneously dispersed among the GAs. In addition, the composite structure was examined using transmission electron microscopy (TEM) to determine the dispersion mechanisms. The electrochemical cycling performance of the pure NMA and NMA/GA composite was evaluated by rate capacitance, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The synthesized NMA/GA was able to provide 89.81% specific capacity retention after the 500th cycle at C/2. The average charge/discharge rates of the obtained cathode show good electrochemical results and exhibit capacities of 190.2,186.3, 185.2, 176.2, 161.2,142.6, and 188.5 mAh g-1 at C/20, C/10, C/5, C, 3C, 5C, and C/20, respectively. EIS data showed an improvement in the impedance of the composite containing GA. According to the results of the electrochemical tests, NMA nanoparticles formed a conductive network with its porous structure thanks to GA, formed a protective layer on the surface, prevented the side reactions between the cathode and the electrolyte, decreased the impedance of the cathode, and increased the redox kinetics. In addition, the changes in the structure were investigated in the NMA/GA composite cathode by XRD, FE-SEM, and Raman analyses at the end of the 50th, 250th, and 500th cycles. In summary, the NMA/GA cathode is expected to play an important role in lithium-ion batteries (LIBs) by taking advantage of its easy synthesis and excellent cycle stability.

Boosting CO2 Electroreduction on Bismuth Nanoplates with a Three-Dimensional Nitrogen-Doped Graphene Aerogel Matrix

Electrochemical CO2 reduction reaction (CO2RR), which uses renewable electricity to produce high-value-added chemicals, offers an alternative clean path to the carbon cycle. However, bismuth-based catalysts show great potential for the conversion of CO2 and water to formate, but their overall efficiency is still hampered by the weak CO2 adsorption, low electrical conductivity, and slow mass transfer of CO2 molecules. Herein, we report that a rationally modulated nitrogen-doped graphene aerogel matrix (NGA) can significantly enhance the CO2RR performance of bismuth nanoplates (BiNPs) by both modulating the electronic structure of bismuth and regulating the interface for chemical reaction and mass transfer environments. In particular, the NGA prepared by reducing graphene oxide (GO) with hydrazine hydrate (denoted as NGAhdrz) exhibits significantly enhanced strong metal-support interaction (SMSI), increased specific surface area, strengthened CO2 adsorption, and modulated wettability. As a result, the Bi/NGAhdrz exhibits significantly boosted CO2RR properties, with a Faradaic efficiency (FE) of 96.4% at a current density of 51.4 mA cm-2 for formate evolution at a potential of -1.0 V versus reversible hydrogen electrode (vs RHE) in aqueous solution under ambient conditions.

Carbon-Coated MnO Quantum Dot-Decorated Three-Dimensional Graphene Aerogel Composite for High-Performance Lithium-Ion Batteries

Herein, carbon-coated MnO QDs decorated on a graphene aerogel (GA, C@MnO QDs/GA) were fabricated by forming a manganese oxide gel in situ on the GA, followed by supercritical drying and carbonization. The composite combines the uniform distribution of ultra-small MnO QDs and the conducting GA with the 3D porous interconnected network structure. The well-dispersed tiny MnO quantum dots can buffer the volume change and shorten the ion diffusion path to improve the reaction kinetics. The GA can provide a 3D conductive channel for rapid electron transfer and Li+ diffusion. When used as anodes for Li-ion batteries, C@MnO QDs/GA electrodes displayed superior electrochemical performance, such as ultra-high discharge capacity, excellent cycling stability, and outstanding rate performance. A high discharge capacity of 1698 mA h g–1 was delivered after 100 cycles at 200 mA g–1, and a capacity of 702 mA h g–1 can be retained at a high current density of 2000 mA g–1. The results suggest that the C@MnO QDs/GA materials designed in this work can be potential anodes for high-performance LIBs, providing meaningful implications for further exploration of oxide anodes for next-generation alkali metal-ion batteries.

An elastic MOF/graphene aerogel with high photothermal efficiency for rapid removal of crude oil

Due to the frequent spill accidents during crude oil exploration and transport, to rapidly cleanup crude oil and eliminate the environmental pollution of oil spill is in high demand. In this work, a three-dimensional graphene aerogel (MEGA) with high elasticity, photothermal conversion capacity and adsorption capacity was prepared for rapid removal of crude oil. The results showed that the as-prepared MEGA exhibited a layered structure, the octahedral HKUST-1 nanoparticles and hydrophobic polydimethylsiloxane (PDMS) coatings were uniformly deposited on the surface. Such a hierarchical micro-nano porous structure not only improved the aerogel's hydrophobicity (water contact angle in air up to 152.7°), but also endowed it with strong oil adsorption capacity (41-118 times of its own weight). Especially, the MEGA showed excellent photothermal conversion capacity. Under light irradiation, its temperature raised to 80℃ from room temperature in 100s. As a result, the adsorption for one drop of crude oil by MEGA was shortened from 5h to 40s, comparing with that in dark condition. In addition, the MEGA showed remarkable elasticity and mechanical stability, it could maintain more than 90% efficiency after 10 adsorption-compression cycles. This study suggests that the prepared MEGA has great potential for rapid removal of crude oil.

Enhancing hydrogen evolution reaction (HER) performance by loading MoS2 nanoflowers into three-dimensional graphene aerogel skeleton

We successfully loaded different quantities of MoS2 nanoflowers (MoS2-NF) into three-dimensional graphene aerogel skeleton (GA) by hydrothermal and freeze-drying process. The prepared MoS2 nanoflowers/graphene hybrid aerogels (denoted as MoS2-NF/GA) exhibit a gradually decreasing initial overpotential and Tafel slope with increasing of MoS2-NF, indicating a gradually improvement of HER performance. The enhancement may be explained by the benefit from excellent conductivity of GA to the acceleration of electrons transferring and the increased MoS2 active sites ascribed from the highly dispersed distribution of MoS2-NF in the GA. This study provides a method for loading controllably nanomaterials into three-dimensional graphene aerogel skeleton and a strategy for enhancing HER performance of MoS2-NF.

Boosting the performance of an iontophoretic biosensing system with a graphene aerogel and Prussian blue for highly sensitive and noninvasive glucose monitoring.

Diabetes and impaired glucose regulation (IGR) threaten the lives and health of numerous patients. Interstitial fluid (ISF) glucose, displaying an excellent correlation with blood glucose, is highly desired to address the limitations of invasive and minimally invasive glucose detection. Herein, we present a screen-printed iontophoretic biosensing system to extract ISF noninvasively and perform in situ instant glucose detection. A three-dimensional graphene aerogel combined with Prussian blue (GA@PB) was introduced as an electron mediator, providing suitable support for glucose oxidase (GOx) immobilization, highly boosting the detection sensitivity. Additionally, a self-made diffuse cell and an ex vivo model were developed to demonstrate the efficacy of ISF extraction based on reverse iontophoresis technology. Highly sensitive and accurate detection of ISF glucose could be achieved with an LOD of 0.26 mM over a 0-15 mM range. Finally, tests on healthy volunteers were conducted to further validate the feasibility of this as-proposed system. Combined with its well flexible and biocompatible features, it holds considerable prospects in the development of wireless wearable biosensors for continuous blood glucose monitoring.

One-pot self-assembled bimetallic sulfide particle cluster-supported three-dimensional graphene aerogel as an efficient electrocatalyst for the oxygen evolution reaction.

The preparation of an electrocatalyst for the oxygen evolution reaction (OER) with high catalytic activity, good long-term durability and rapid reaction kinetics through interface engineering is of great significance. Herein, we have developed a bimetallic sulfide particle cluster-supported three-dimensional graphene aerogel (FeNiS@GA), which serves as an efficient electrocatalyst for OER, by a one-step hydrothermal method. Profiting from the synergy of the FeNiS particle cluster with high capacitance and GA with its three-dimensional porous nanostructure, FeNiS@GA shows a high specific surface area, large pore volume, low contact resistance, and decreases the electron and ion transport routes. FeNiS@GA exhibits outstanding OER activity (when the current density is 50 mA cm-2, the overpotential is 341 mV), low Tafel slope (63.87 mV dec-1) and remarkable stability in alkaline solutions, outperforming FeNiS, NiS@GA, FeS@GA and RuO2. Due to its simple synthesis process and excellent electrocatalytic performance, FeNiS@GA shows great potential to replace noble metal-based catalysts in practical applications.