Three-dimensional Graphene Aerogel Research Articles

Three-dimensional graphene aerogel supported Ir nanocomposite as a highly efficient catalyst for chemoselective cinnamaldehyde hydrogenation

A three-dimensional graphene aerogel-supported Ir (Ir/GA) nanocomposite with interconnected porous framework and high dispersion of Ir nanoparticles is synthesized via a simple yet effective “co-reduction self-assembly” strategy, in which the chemical co-reduction of graphene oxide and H2IrCl6 occurs in the presence of glycerol and Ir is directly incorporated onto the reduced graphene oxide nanosheets. The Ir/GA possesses rich hierarchical porosity, a low amount of oxygen-containing functional groups, and a certain amount of Irδ- species, which notably improve the accessibility to both sides of the resulting reduced graphene oxide nanosheets, number of active Ir sites, electron transfer ability, and affinity of active Ir with CO band. As a catalyst in chemoselective cinnamaldehyde (CMA) hydrogenation towards cinnamyl alcohol (CMO), the Ir/GA shows satisfactory CMA conversion of 85.8% and CMO selectivity of 83.2% with a high TOF activity of yielding CMO up to 17.5 h−1 at reaction time of 1 h. Moreover, the Ir/GA delivers good catalytic durability even after seven successive cycles without pronounced activity deterioration. This study highlights the exciting possibility to synthesize highly efficient graphene-supported precious metal catalysts with multiscale control by overall consideration in mass transportation, metal dispersion, metal-support interactions, and electronic density of active sites for chemoselective CMA hydrogenation.

Tuning oxygen clusters on graphene oxide to synthesize graphene aerogels with crumpled nanosheets for effective removal of organic pollutants

Previously available synthesis of crumpled graphene is always based on external substrates or triggers, and it is still a daunting challenge to construct three-dimensional (3D) porous graphene aerogels with crumpled nanosheets without additional corrugation-inducers. Here, we report a novel and facile method to fabricate crumpled dispersive nanosheets in water directly by tuning oxygen clusters on graphene oxide itself through general alkali-treatment at 70 °C. Given this, 3D graphene aerogel with crumpled nanosheets has been successfully constructed in aqueous via a common sol-gel process. In this kind of 3D architecture, the self-restacking of graphene nanosheets is thoroughly inhibited, and abundant diffusion paths and voids are created. The thus fabricated crumpled aerogel exhibits high elasticity and hydrophobicity with superior absorption capacity of organic pollutants, which is 224%–406% higher than that of conventional graphene aerogels assembled by flat and stiff plates, outperforming most of the pioneering reported graphene aerogels synthesized by sol-gel method. Intriguingly, this architecture also presents excellent recyclability. The suggested facile fabrication of crumpled aerogel with attractive 3D configuration opens a door to promote the performance of graphene-based devices by tuning oxygen clusters and graphitic domains on nanosheets for specific energy storage and sensors applications.

Aerogels prepared from polymeric β-cyclodextrin and graphene aerogels as a novel host-guest system for immobilization of antibodies: a voltammetric immunosensor for the tumor marker CA 15-3.

A three-dimensional porous network graphene aerogel (GAs) with large specific area and excellent conductivity was loaded with β-cyclodextrin polymer (Pβ-CD) to serve as a support for immobilization of antibodies. A highly sensitive immunosensor for the cancer marker carbohydrate antigen 15-3 (CA15-3) was designed based on the use of Pβ-CD/GAs. The large specific area of GAs warrants high loading with antibodies, and their excellent electrical conductivity warrants strong electrical signals. Based on the synergistic effect of GAs and Pβ-CD, an immunoassay was designed that is making use of hexacyanoferrate as an electrochemical probe and having a pleasantly low working potential of 0.2V (vs. SCE). Response is linear in the 0.1mUmL-1 to 100UmL-1 activity range, and the lower detection limit is 0.03mUmL-1 (at S/N= 3). The immunoassay is stable, selective and reproducible. It was applied to the analysis of spiked samples, and results were satisfactory. Graphical abstract Schematic of an electrochemical immunoassay for the carbohydrate antigen 15-3. It is based on the use of β-cyclodextrin polymer and a graphene aerogel.

Low-Cost and Highly Efficient Metal-Free Electrocatalysts for Oxygen Reduction Reaction: Environment-Friendly Three-Dimensional B, N Co-doped Graphene Aerogels

Nitrogen (N) and boron (B) co-doped graphene materials have been certified as promising catalyst for oxygen reduction reaction (ORR), since the dual doping of foreign atoms could induce a unique electronic structure in graphene and create a synergistic coupling effect between heteroatoms. However, previously reported B, N co-doped graphene materials suffered from shortcomings such as needing highly toxic precursors or high cost or complex preparation procedures. Herein, one highly efficient metal-free ORR catalyst, three-dimensional graphene aerogels (GAs) co-doped with B and N using economical and environmentally friendly melamine and boric acid as heteroatom precursors, was prepared through a one-step hydrothermal method. The as-prepared microporous B, N co-doped GAs showed excellent electrochemical catalytic performances for ORR under alkaline condition (0.1 M KOH) with a much more positive onset potential (0.994 V vs. RHE) than most of the existing B, N co-doped ones, a dominant four-electron transfer mechanism (n = 3.73 at 0.6 V), as well as excellent stability.

Flexible Pt-Promoted Graphene Aerogel Monolith: Versatile Catalyst for Room-Temperature Removal of Carbon Monoxide, Formaldehyde, and Ethylene

Three-dimensional flexible Pt-promoted graphene aerogel monolith is developed through a one-step solvothermal process as a versatile catalyst for removal of CO, HCHO, and C2H4 at room temperature. In this synthesis, ethylene glycol was employed as both the reducing agent and the solvent which could accelerate the in situ reduction of GO and metal ions during the solvothermal process, leading to the assembly and cross-linking of GO to form a three-dimensional (3D) network. Therefore, the obtained Pt-promoted graphene aerogel monolith exhibits an interconnected, honeycomb-like 3D porous framework with highly dispersed Pt (0) species, making it ideal for catalytic oxidation. Such monolith shows a high performance for the catalytic oxidation of CO, HCHO, and C2H4, with 100% conversion at room temperature, with an excellent stability longer than 72 h. These results demonstrate that the flexible Pt-promoted graphene aerogel monolith gives significance on catalytic oxidation, which could be applied in eliminatin...

Three-dimensional Nitrogen-Doped Graphene Aerogel as an Excellent Electrode Material for Highly Sensitive Determination of Midecamycin

Three-dimensional Nitrogen-Doped Graphene Aerogel as an Excellent Electrode Material for Highly Sensitive Determination of Midecamycin

Three-dimensional network graphene aerogel for enhancing adsorption and visible light photocatalysis of nitrogen-doped TiO2

A series of novel N-doped TiO2/graphene aerogel (NTGA) composites were successfully prepared by a chemical reduction self-assembly method. The NTGA composites were characterized by XRD, XPS, SEM and TEM, and their photo-generated electron transfer performance was measured by EIS. All NTGA composites exhibit excellent adsorption property and visible light photocatalytic ability, and the removal rates of Methlyene blue (MB) (20 ppm, 100 ml) reach to more than 90%. In sum, this strategy provides a new thought to enhance the adsorption and photocatalytic performance of N-doped TiO2 (NT).

3D graphene aerogel supported FeNi-P derived from electroactive nickel hexacyanoferrate as efficient oxygen evolution catalyst

It is essential to design an oxygen evolution reaction (OER) electrocatalyst with smaller overpotential to improve water electrolyzer efficiency. Here, we report a simple method to incorporate nickel hexacyanoferrate into the three-dimensional (3D) graphene aerogel (GA) structure (NiHCF/GA), through which we have derived OER active FeNi-P/GA catalyst by heating with the phosphide source. Structural characterization data disclosed that the NiHCF derived FeNi-P particles were uniformly distributed in the 3D GA network. The obtained FeNi-P/GA catalyst exhibits precursor ([K3Fe(CN)6] and NiCl2) concentration-dependent electrocatalytic activity towards OER. Linear sweep voltammetry (LSV) study shows OER on the optimized FeNi-P/GA catalyst surface commenced at 1.46 V vs. RHE and demands only 280 mV overpotential to achieve the benchmark current density of 10 mA.cm−2. Also, the FeNi-P/GA catalyst displayed a Tafel slope of 43 mV.dec−1, suggesting its superior OER performance in alkaline condition.

Three-dimensional β-cyclodextrin functionalized graphene aerogels: An enhanced electrochemical sensing platform for quantification of Ponceau 4R

β-Cyclodextrin (β-CD) with supramolecular recognition capability is widely used as signal amplifier in the fabrication of electrochemical sensor. Unfortunately, its poor electrical conductivity limits its application. To improve its conductivity and increase the loading of β-CD on the modified electrode, in this paper, three-dimensional (3D) porous graphene aerogels (GAs) were introduced as substrate material. The as-prepared β-CD/GAs composite offers high electrical conductivity, large specific surface area of 3D GAs coupled with the excellent adsorption ability of β-CD, and its application as electrochemical sensing platform for Ponceau 4R detection was investigated. Benefiting from the synergy between β-CD and GAs, the β-CD/GAs electrode could detect Ponceau 4R in a wide linear ranging from 1.0 nM to 1.0 μM with a low detection limit of 0.3 nM. Furthermore, the β-CD/GAs electrode also exhibited good anti-interference performance and long term stability, and was capable of detecting Ponceau 4R in the food samples.

A porous graphene sorbent coated with titanium(IV)-functionalized polydopamine for selective lab-in-syringe extraction of phosphoproteins and phosphopeptides.

A novel polydopamine coated three-dimensional porous graphene aerogel sorbent carrying immobilized titanium(IV) ions(denoted as Ti4+@PDA@GA) was fabricated without using an organic solvent. The material is shown to be a viable carbon foam type of monolithic sorbent for selective lab-in-syringe enrichment of phosphoproteins and phosphopeptides. The phosphoproteins can be separated from a sample by aspiration and then bind to the sorbent. The analytes then can be dispensed within 5min. The weight percent of titanium in the monolith typically is 14%, and the absorption capacities for the model proteins β-casein and κ-casein are 1300 and 1345mgg-1, respectively. The absorption capacities for nonphosphoproteins are much smaller, typically 160mgg-1 for β-lactoglobulin, 125mgg-1 for bovine serum, and 4.8mgg-1 for lysozyme. The results demonstrate that the selectivity for phosphoproteins was excellent on multiple biological samples including standard protein mixtures, spiked human blood serum, and drinking milk. The selective enrichment of phosphopeptides also makes the method a promising tool in phosphoproteomics. Graphical abstract Schematic of a polydopamine coated three-dimensional porous graphene aerogel for immobilization oftitanium(IV) ions. The material served as a monolithic sorbent for selective enrichment of phosphopeptides and phosphoproteins from biological samples. The enrichment process can be carried out conveniently using a lab-in-syringe way.

Free-Standing 3D Porous N-Doped Graphene Aerogel Supported Platinum Nanocluster for Efficient Hydrogen Production from Ammonia Electrolysis

Ammonia oxidation reaction (AOR) is an environmentally friendly electrochemical technology for hydrogen production. Nowadays, exploiting low-costing, high-performance and robust catalysts for AOR is essential to improve the overall efficiency of ammonia electrolysis cell (AEC). Here, we report the synthesis and characterization of a novel free-standing three-dimensional (3D) porous N-doped graphene aerogel (NGA) anchored with Pt nanocluster (Pt/NGA) monolithic material as a high-performance and robust electrocatalyst for hydrogen production from AEC. The NGA substrate was facilely fabricated through a self-assemble process into the randomly arranged 3D porous backbone structure with graphene oxide (GO) and poly(oxypropylene)diamine D400 as precursors in a pure water solvent. Then, the Pt nanocluster-like structures were uniformly dispersed and embedded onto NGA through the simple electrodeposition method. The as-prepared Pt/NGA monolithic materials exhibited a higher ammonia electro-oxidation activity wit...

Molecular interaction between three-dimensional graphene aerogel and enzyme solution: Effect on enzyme structure and function

New membrane materials and processes have been extensively developed due to urgent needs for much more economic separation processes. Recently, graphene has been confirmed to be an excellent separation membrane. As there is no support in the obtained three-dimensional (3D) architecture constructed from tubular graphene network, it is possible to take full advantage of the large surface of graphene. In this study 3D graphene aerogels were synthesized by a simple method and modified to adjust hydrophilicity of the samples to achieve high liquid volumetric rate. Modified samples were used for the filtration of the enzymes including amylase, cellulase, lipase and protease. Slightly differently interactions between enzymes and samples causing different flow rates. To investigate changes in physicochemical properties of filtered enzyme, catalytic activity and structure of untreated and filtered samples were obtained using circular dichroism spectra and colorimetric assays. The configurations and functions of cellulase, lipase and protease were maintained during the processes. The results demonstrate that 3D graphene aerogels is a promising material for enzyme filtration and keep the aim of protein filtration which is providing high quality protein sample to achieve original information from interested protein species.

Flower-like nanostructured V3S4 grown on three-dimensional porous graphene aerogel for efficient oxygen reduction reaction

A novel flower-like nanostructured V3S4/graphene aerogel (V3S4-GA) hybrid is successfully synthesized as an efficient electrocatalyst for oxygen reduction reaction (ORR). The flower-like V3S4 homogeneously grows on the surface of graphene, which provides a large contact surface area with electrolyte and abundant active sites. The strong covalency of VsbndS bond and the abundant unoccupied d-orbits of vanadium atoms are propitious to the exchange of the adsorbed oxygen molecular. The porous GA exists an excellent continuous electric conductive network for electron transportation and enough nanospace for O2 adsorption and reaction. Such unique nanostructures offer the synthesized V3S4/GA hybrid an excellent ORR catalytic performance, including a high electron transfer per oxygen molecule of 3.97, a high kinetic current density of 9.5 mA cm−2 at −0.5 V vs. Ag/AgCl, a high methanol resistance and a good durability.

Flower-like MoS2 supported on three-dimensional graphene aerogels as high-performance anode materials for sodium-ion batteries

Flower-like MoS2 supported on three-dimensional graphene aerogel (MoS2/GA) composite has been prepared by a facile hydrothermal method followed by subsequent heat-treatment process. Each of MoS2 microflowers is surrounded by the three-dimensional graphene nanosheets. The MoS2/GA composite is applied as an anode material of sodium-ion batteries (SIBs) and it exhibits high initial discharge/charge capacities of 562.7 and 460 mAh g−1 at a current density of 0.1 A g−1 and good cycling performance (348.6 mAh g−1 after 30 cycles at 0.1 A g−1). The good Na+ storage properties of the MoS2/GA composite could be attributed to the unique structure which flower-like MoS2 are homogeneously and tightly decorated on the surface of three-dimensional graphene aerogel. Our results demonstrate that as-prepared MoS2/GA composite has a great potential prospect as anodes for SIBs.

Prussian Blue-Derived Iron Phosphide Nanoparticles in a Porous Graphene Aerogel as Efficient Electrocatalyst for Hydrogen Evolution Reaction.

Tailoring of new hydrogen evolution reaction (HER) electrocatalyst with earth abundant elements is important for large scale water splitting and hydrogen production. In this work, we present a simple synthetic method for incorporating iron phosphide (FeP) particles into three-dimensional (3D) porous graphene aerogel (GA) structure. The FeP formed in porous 3D GA (FeP/GA) is derived from electroactive Fe hexacyanoferrate (FeHCF). The advantage of incorporating FeP, in the porous 3D graphene network enables high accessibility for HER. As synthesized FeP/GA catalyst shows good electrocatalytic activity for HER in both acidic and alkaline solutions. The developed method can be useful for synthesizing metal hexacyanoferrate derived mono/bimetal phosphide catalyst in porous 3D graphene aerogels.

Superelastic and multifunctional graphene-based aerogels by interfacial reinforcement with graphitized carbon at high temperatures

Although lightweight and three-dimensional graphene aerogels and foams combining ultrahigh electrical conductivity, superelasticity and fatigue resistance are highly desirable for widespread applications, it remains a large challenge to construct a multifunctional framework affording the rapid electron transport and efficient load transfer due to the weak interfaces between highly reduced graphene oxide sheets. Herein, we report an efficient approach for fabricating an integrated graphene aerogel by bridging its reduced graphene oxide sheets with polyimide macromolecules followed by graphitization at 2800 °C. During the graphitization process, the reduced graphene oxide sheets are thermally reduced to graphene efficiently by removing their residual oxygen-containing groups and healing their defects, while the polyimide component is graphitized to turbostratic carbon to bridge the graphene sheets, resulting in an integrated graphene aerogel with satisfactory mechanical and functional performances, including ultrahigh electrical conductivity (>1000 S m−1) at a low density, unprecedented high electromagnetic interference shielding effectiveness of ∼83 dB in X-band, 90% reversible compressibility, and reliable resistance to fatigue for 1000 compressive cycles at 50% strain. The integrated graphene aerogels with such multifunctional performances hold a great promise for applications as electromagnetic interference shielding materials, oil adsorbents, and conductive scaffolds for polymer nanocomposites.

Bio-inspired FeN5 moieties anchored on a three-dimensional graphene aerogel to improve oxygen reduction catalytic performance

A three-dimensional graphene aerogel supported FeN5 composite with an explicit five-coordinated Fe–N bond is synthesized, which shows excellent ORR catalytic performance.

Assessment of graphene aerogel matrix solid-phase dispersion as sample preparation for the determination of chlorophenols in soil

Three-dimensional graphene aerogels (GAs) were synthesized by hydrothermal reduction and introduced as dispersing materials of matrix solid-phase dispersion for the determination of six chlorophenols in soil via high performance liquid chromatography.

Fabrication of macroporous reduced graphene oxide composite aerogels reinforced with chitosan for high bilirubin adsorption.

Numerous adsorbents have been reported for the removal of bilirubin, which is a well-known endogenous toxin. Three-dimensional graphene sponges and aerogels have been fully studied in the adsorption field but little in hemoperfusion especially for bilirubin adsorption. In this study, macroporous reduced graphene oxide (GO) aerogels were fabricated by a chemical reduction method. Besides, chitosan was introduced in the aerogels during the reduction process to improve their mechanical properties. The graphene oxide composite aerogels reinforced with chitosan (rGO/CS) were investigated using scanning electron microscopy (SEM), Fourier Transform Infrared Spectrometry (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET). Furthermore, the mechanical properties test showed the reinforced mechanical strength of the rGO/CS aerogels. The adsorption performance of the aerogels for bilirubin was studied in detail, showing a high adsorption capacity (458.9 mg g−1) and a fast adsorption rate. Moreover, the low hemolysis ratio and negligible anticoagulant activity of rGO/CS aerogels suggested good blood compatibility. The mesoporous structure of the aerogels can provide good mechanical strength, and the macroporous structure of the rGO/CS aerogels shows a good adsorption capacity, which would have potential applications in bilirubin adsorption.

A facile strategy for fabricating hierarchical nanocomposites of V2O5nanowire arrays on a three-dimensional N-doped graphene aerogel with a synergistic effect for supercapacitors

As one of the most promising candidates for supercapacitor electrodes, vanadium pentoxide (V2O5) usually suffers from poor electronic conductivity and small ionic diffusivity.