Three-dimensional Aerogel Research Articles

Three-Dimensional Hierarchical Reduced Graphene Oxide/Tellurium Nanowires: A High-Performance Freestanding Cathode for Li-Te Batteries.

Three-dimensional aerogel with ultrathin tellurium nanowires (TeNWs) wrapped homogeneously by reduced graphene oxide (rGO) is realized via a facile hydrothermal method. Featured with high conductivity and large flexibility, the rGO constructs a conductive three-dimensional (3D) backbone with rich porosity and leads to a free-standing, binder-free cathode for lithium-tellurium (Li-Te) batteries with excellent electrochemical performances. The cathode shows a high initial capacity of 2611 mAh cm(-3) at 0.2 C, a high retention of 88% after 200 cycles, and a high-rate capacity of 1083 mAh cm(-3) at 10 C. In particular, the 3D aerogel cathode delivers a capacity of 1685 mAh cm(-3) at 1 C after 500 cycles, showing pronounced long-cycle performance at high current density. The performances are attributed to the well-defined flexible 3D architecture with high porosity and conductivity network, which offers highly efficient channels for electron transfer and ionic diffusion while compromising volume expansion of Te in charge/discharge. Owing to such advantageous properties, the reported 3D rGO/tellurium nanowire (3DGT) aerogel presents promising application potentials as a high-performance cathode for Li-Te batteries.

Facile synthesis route for MoS2-polyvinylpyrrolidone aerogels

Three-dimensional (3D) aerogels with low density, high porosity and large surface area have attracted increasing attention and exhibit numerous applications. However, the material types of aerogels are still very limited. Herein, we report a facile synthesis route to prepare MoS2-polyvinylpyrrolidone (PVP) aerogels via direct frozen-drying from primitive solution with PVP, which plays a key role to obtain aerogels. The good wettability both on water and oil of PVP makes it easily cover on the surface of MoS2 nanosheets, which promotes the sheets connection with each other. The density of the obtained MoS2-PVP aerogels can be tuned from 9.2 to 33.8mg/cm3 via simply changing the concentrations of the precursors. Importantly, our current approach has been successfully applied to prepare other 2D or 1D material-PVP aerogels, taking boron nitride-PVP and carbon nanotubes-PVP aerogels as examples.

Cost-Effective Three-Dimensional Graphene/Ag Aerogel Composite for High-Performance Sensing

A cost-effective new approach was developed for the fabrication of a three-dimensional reduced graphene oxide/Ag nanoparticle composite, where Ag nanoparticles of 18.0±1.8nm in diameter were uniformly dispersed throughout a reduced graphene oxide aerogel. When used as a non-enzymatic sensor, the composite demonstrated excellent electrocatalytic performance toward the detection of H2O2, i.e. a broad linear range of 0.016–27mmolL−1, high sensitivity of 419.7μAmmol−1Lcm−2, low detection limit of 6.8μmolL−1 and superior selectivity against impurities such as citric acid, ascorbic acid and glucose. The superior performance is ascribed to the large interfacial area provided by the three-dimensional aerogel and the enhanced electron transfer by a great number of the fine Ag nanopaticles uniformly dispersed throughout the aerogel.

Photoluminescent Aerogels from Quantum Wells

Highly porous self-supported three-dimensional aerogel monoliths are synthesized from strongly quantum confined quantum wells, namely, 5 monolayer thick CdSe and CdSe/CdS core/crown nanoplatelets. The aerogels are synthesized by hydrogelation of the aqueous quantum well solutions and subsequent supercritical drying. The aerogels are optically characterized by UV–vis absorption spectroscopy, emission spectroscopy, and photoluminescence (PL) decay analysis. Morphological and structural characterizations are achieved by transmission electron microscopy, scanning electron microscopy, and X-ray diffractometry. The macroscopic aerogels exhibit extremely low densities of 0.038 ± 0.007 g·cm–3 and a significantly high specific surface area of 219 m2·g–1 with nearly entirely (111) as the exposed crystal facet. Moreover, the aerogels feature properties related to quantum confinement comparable to those of their original building blocks with photoluminescence quantum yields up to 10.3%.

Synthesis of a novel Al2O3–SiO2 composite aerogel with high specific surface area at elevated temperatures using inexpensive inorganic salt of aluminum

We have developed a new sol–gel route to synthesize Al2O3–SiO2 composite aerogel using inexpensive inorganic salt of aluminum. The approach, which is straightforward, inexpensive, and safe, can be employed to produce a monolithic mesoporous material with a high specific surface area, which is heat-treated at high temperatures. The results show that SiO2 is essentially amorphous, whereas Al2O3 predominately exists as polycrystalline boehmite which consists of fibrous particles and web-like microstructures. As the heat treatment temperature increases to 600°C, the structural transition from boehmite to γ-Al2O3 occurs within the composite. When the composite is heat-treated at 1100°C, SiO2 crystallization occurs and the mullite phase begins to appear. The specific surface area decreases with an increase in heat treatment temperatures; however, it remains 120m2/g until 1200°C. The heat treatment process improves the quality of the three-dimensional aerogel network, and the pore distribution becomes uniform after heat treatment.

Three-dimensional MnO2 ultrathin nanosheet aerogels for high-performance Li–O2 batteries

Two-dimensional (2D) MnO2 ultrathin nanosheets have been assembled into three-dimensional (3D) aerogels, which can help prevent the restacking of 2D nanocrystals, and consequently lead to enhanced performances in Li–O2 batteries.

Enhanced photocatalytic activities of three-dimensional graphene-based aerogel embedding TiO2 nanoparticles and loading MoS2 nanosheets as Co-catalyst

A novel graphene-based three-dimensional (3D) aerogel embedded with two types of functional nanomaterials had been prepared by a facile one-pot hydrothermal process. During the hydrothermal reaction, graphene, TiO2 nanoparticles and MoS2 nanosheets were self-assembled into the 3D interconnected networks aerogel, where the uniformly dispersed TiO2 nanoparticles were densely anchored onto the graphene nanosheets and decorated with the ultrathin MoS2 nanosheets. The UV–vis DRS and PL spectra measurement shows that the MoS2/P25/graphene aerogel exhibits enhanced light absorption and efficient charge separation properties. As a new photocatalyst, the photocatalytic activity was evaluated by photoelectrochemical test and photodegradation methyl orange (MO) under UV irradiation, an improvement of photocurrent was observed, as 6 times higher for MoS2/P25/graphene aerogel (37.45 mA/cm2) than pure P25 at +0.6 V, and the fastest photodegradation of MoS2/P25/graphene aerogel was found within 15 min. The improved photocatalytic activity is attributed to the porous structure, good electrical conductivity and the maximization of accessible sites of the unique 3D graphene aerogel, the increasing active adsorption sites and photocatalytic reaction centers for the introduction of MoS2 nanosheets, and the positive synergetic effect between the three components in this hybrid. This work demonstrates that the as-prepared MoS2/P25/graphene aerogel may have a great potential application in photoelectrochemical hydrogen production and pollution removal.

Comparative Study of Aerogels Obtained from Differently Prepared Nanocellulose Fibers

This article describes the fabrication of nanocellulose fibers (NCFs) with different morphologies and surface properties from biomass resources as well as their self-aggregation into lightweight aerogels. By carefully modulating the nanofibrillation process, four types of NCFs could be readily fabricated, including long aggregated nanofiber bundles, long individualized nanofibers with surface C6 -carboxylate groups, short aggregated nanofibers, and short individualized nanofibers with surface sulfate groups. Free-standing lightweight aerogels were obtained from the corresponding aqueous NCF suspensions through freeze-drying. The structure of the aerogels could be controlled by manipulating the type of NCFs and the concentration of their suspensions. A possible mechanism for the self-aggregation of NCFs into two- or three-dimensional aerogel nanostructures was further proposed. Owing to web-like structure, high porosity, and high surface reactivity, the NCF aerogels exhibited high mechanical flexibility and ductility, and excellent properties for water uptake, removal of dye pollutants, and the use as thermal insulation materials. The aerogels also displayed sound-adsorption capability at high frequencies.

A novel three-dimensional aerogel biochip for molecular recognition of nucleotide acids

Mesoporous aerogel was produced under regular atmospheric conditions using the sol–gel polymerization of tetraethyl orthosilicate with an ionic liquid as both solvent and active agent. This was then used to build a three-dimensional structure to recognize nucleotide acids. Fourier transformation infrared spectroscopy, scanning electron microscopy, 29Si solid-state nuclear magnetic resonance, and Brunauer–Emmett–Teller instruments were used to characterize this 3D aerogel, demonstrating that it had high porosity and large internal networking surface area that could capture nucleotide acids. The functionality of molecular recognition on nucleotide acids was demonstrated by immobilizing an oligonucleotide to probe its DNA target and confirming the tagged fluorescent signals by confocal laser scanning microscopy. The results indicated that the as-prepared 3D bioaerogel was capable of providing a very large surface area to capture and recognize human gene ATP5O.