Subsequent Thermal Reduction Research Articles

Multifunctional ultralight magnetic Fe3O4@SiO2/Ti3C2Tx/rGO aerogel with efficient electromagnetic wave absorption and thermal management properties

The rational and effective fabrication of multicomponent materials, coupled with innovative microstructure design, remains a formidable challenge in achieving efficient electromagnetic wave absorption (EMA) behaviors to meet the requirement of rapid advances in electronics. Herein, a three-dimensional (3D) hierarchically porous Fe3O4/SiO2/Ti3C2Tx MXene/rGO (FSMRG) aerogels were obtained via a directional freeze-drying and subsequent thermal reduction strategy. It has been found that with the filling ratio of 5 wt%, the ultralight FSMRG-2 aerogel (7.42 mg cm−3) exhibits optimal EMA performances with a minimum reflection loss (RLmin) of −76.6 dB, and the corresponding maximal effective absorption bandwidth (EAB) is up to 5.36 GHz covering the frequency ranges from 12.48 GHz to 17.84 GHz. The outstanding EMA performances of FSMRG-2 aerogel can be attributed to the synergy effects from the multicomponent interfacial polarization, multiple loss pathways and favorable impedance matching as evidenced with the electromagnetic parameter analysis. In addition, the FSMRG-2 aerogel also displays excellent hydrophobicity and thermal insulation capabilities, rendering them suitable for application in complicated environments characterized by humid and high-temperature conditions. Therefore, this study presents a reliable and facile strategy for the precise construction of lightweight, efficient and multifunctional EMA materials.

High anti-corrosive and Scalable CDs/BCN heterostructure photocatalysts for efficient H2 production in natural seawater

Photocatalytic natural seawater-derived splitting to produce hydrogen is one of the most potential strategies to alleviate the shortage of freshwater resources and energy crisis. Nevertheless, the complicated composition of natural seawater poses substantial challenges to the activity and stability of photocatalysts. Here, we report on the fabrication of carbon dots (CDs) and B elements co-modified carbon nitride (i.e. CDs/BCN) via precursor-mediated supramolecular self-assembly and subsequent NaBH4-assisted thermal reduction as well as its implementation as seawater-derived H2 production. The fabricated CDs/BCN exhibits the flaky porous structure capable of providing more transport channels for the generated gases (e.g. H2) and precipitates (e.g. Mg(OH)2, Ca(OH)2) during the seawater splitting process. Benefitting from cooperation of CDs and B elements i.e. the inhibited recombination of electron-hole pairs as well as the extended optical absorption range of CN, the optimal CDs/BCN-2 under visible-light irradiation exhibits the high H2 production rate up to 10369 μmol g-1 h-1 in natural seawater. The proven satisfactory reusability and the corresponding structural stability demonstrate the excellent corrosion resistance of CDs/BCN-2 in natural seawater. Additionally, CDs/BCN-20 photocatalyst synthesized via 20-fold precursor amplification procedure still displays efficient photocatalytic performance of 9022 μmol g-1 h-1, indicating its potential for industrial applications.

Resilient Si@C architecture fabricated by mechanochemical conjugation and thermal reduction for lithium storage: Simulation on interfacial state evolution

Synchronal comminution via high-energy bead milling not only efficiently pulverizes Si particles and exfoliates graphene oxide (GO) sheets but also facilitates Si surface functionalization and intensify Si-C conjugation. After a thermal reduction, a well-wrapped Si@C anode material can be fabricated for lithium storage. The discharge specific capacities of this Si@C composite sustain at 1110.3 mAh g−1 after 300 cycles at 1 A g−1 and 316.4 mAh g−1 for 800 cycles at 5 A g−1, which are respectively 1.35 and 2.07 times that of its random blended Si/C counterpart. By employing molecular dynamics (MD) simulations with ReaxFF reactive force field to investigate the mechanochemical reactions between Si and GO amidst high-energy milling, an atomic scale portrayal of Si crystal fragmentation and Si-C bonding can be depicted. Analyses focusing on the differential forces exerted on various Si crystal planes, coupled with potential energy (PE) trends, reveal a higher propensity for cleavage in (111) plane, with (311) plane followed. Radial distribution function (RDF) outcomes indicate that ball milling leads to substantial disruption of crystalline order in Si particles, generating a plethora of Si dangling bonds. This disruption stimulates the formation of SiOOC, SiOC and SiC bonds at the Si/C interface, thus enhancing the integration of GO with Si substrate. Subsequent thermal reduction processes not only restore the structural order of Si and GO but also consolidate Si/C bonding.

A SYSTEMATIC INVESTIGATION OF THE STRUCTURAL CHANGES IN CHEMICALLY AND THERMALLY REDUCED GRAPHENE OXIDE USING RAMAN AND XRD

This investigation aimed to explore the characteristics of reduced graphene oxide (rGO) through a comprehensive approach. The synthesis of graphene oxide (GO) began with a customized adaptation of the modified Hummer’s method, followed by subsequent chemical and thermal reduction processes. Chemical reduction involved the use of ascorbic acid, hydrazine hydrate, and sodium borohydride, while thermal reduction occurred at various temperatures in the presence of hydrogen. The study employed a diverse array of analytical techniques to unravel the structural and chemical intricacies of the material. X-ray diffraction (XRD) revealed significant changes indicative of structural transformations. Raman spectroscopy meticulously examined defects and layer formations. Scanning Electron Microscopy (SEM) visualized the evolutionary aspects of the material’s structure. UV–VIS spectroscopy is employed to analyze the optical bandgap of the sample, and the primary importance of this study lies in its application potential for solar cells.

Amorphous Pt-decorated α-Fe2O3 sensor with superior triethylamine sensing performance prepared by a one-step impregnation method

Noble metals are widely used additives to improve the sensing performance of conductometric metal oxide gas sensors. Although amorphous noble metal particles are expected to further improve the gas sensor response, common techniques often result in crystalline nanoparticles. Herein, an amorphous Pt nanoparticle-decorated α-Fe2O3 sensor was prepared via a temperature-controlled facile one-step impregnation method without the use of a reductant, surfactant, or subsequent thermal reduction. The amorphous Pt-functionalized α-Fe2O3 exhibited superior sensing performance to triethylamine, achieving 100 °C and 140 °C decreases in the optimal working temperature, and had better selectivity, with 22-fold and 14-fold improvements in gas response when compared to those of crystallized Pt-functionalized α-Fe2O3 and pristine α-Fe2O3, respectively. The as-prepared amorphous Pt-decorated α-Fe2O3 sensor showed great promise as a promising triethylamine sensor, and the newly developed facile impregnation method was shown to be an effective strategy to synthesize amorphous noble metal-decorated metal oxide gas sensors.

Thermally Reduced Graphene Oxide Membranes From Local Kazakhstan Graphite “Ognevsky”

AbstractThe properties of pure graphene and reduced graphene oxide (RGO) are close, so thermal annealing is a simple, safe and more cost‐effective alternative, in comparison to other methods to produce graphene oxide (GO) on a significant scale. In this work, for the first time, for the production of GO and its membrane with subsequent thermal reduction, local Kazakhstan “Ognevsky” graphite was used as the initial raw material. The GO membrane was obtained by vacuum filtration and subjected to thermal annealing at various temperatures in a hydrogen atmosphere. It was noticed, that after the thermal recovery of GO membranes, their physical and chemical properties changed. This changes show the possibility of using GO new membranes as a potential material for sensitive elements, such kind of gas and humidity sensors. In this regard, GO and RGO membranes were studied by: SEM, EDX, FTIR, XRD, TGA and Raman spectroscopy. This work demonstrates a new and efficient strategy for manufacturing high performance RGO membranes from local raw materials.

Characteristics and Electrochemical Performance of Hydroxyl-Functionalized Graphene Quantum Dot-Coated Si Nanoparticles/Reduced Graphene Hybrid Anodes for Advanced Li-Ion Batteries

By powering sophisticated lithium-ion batteries (LIBs), silicon/carbon (Si/C) composites have the potential to accelerate the sustainable energy transition. This is a first-of-its-kind Si/C hybrid with hydroxyl-functionalized graphene quantum dots (OH-GQD) electrostatically assembled within interconnected reduced graphene oxide networks (OH-GQD@Si/rGO) prepared through solution-phase ultrasonication and subsequent one-step, low-temperature annealing and thermal reduction. The OH-GQD@Si/rGO hybrid utilized as the LIB anode delivered a high initial specific capacity of 2,229.16, 1,303.21, and 1,090.13 mAh g−1 reversible capacities at 100 mA g−1 after 50 and 100 cycles, and recovered 1,473.28 mAh g−1 at rates as high as 5 A g−1. The synergistic benefits of the OH-GQD/rGO interface give dual, conductive carbon protection to silicon nanoparticles. Consecutive Si surface modifications improved Si–rGO contact modes. The initial OH-GQD carbon coating increased storage capacity through vacancy defects changing the electron density in the lattice, whereas hydroxyl functionality at the edges acted as active storage sites. Secondary protection through rGO encapsulation improved Si conductivity and usage by providing continuous electron/ion routes while minimizing Si volume variations. The proposed OH-GQD/rGO hybridization as a dual-carbon protection strategy to Si stabilized the solid electrolyte interface leading to electrode stability. This work is expected to advance the development of next-generation Si-based LIB anodes.

Increasing the efficiency and cycle life of Na-O2 batteries based on graphene cathodes with heteroatom doping

To overcome the challenges of Na-O2 batteries with respect to efficiency, capacity, and cycle life as well as to develop cheap, metal-free, and abundant electrocatalysts, we explored boron and nitrogen-functionalized graphene aerogels prepared by the hydrothermal self-assembly of graphene oxide with subsequent thermal reduction. The results showed an improve of both the cycling overpotential and the coulombic efficiency for the functionalized graphene aerogels. However, the nitrogen-containing cathode presented a shortened cycle life and decreased charging stability. The postmortem analysis of the full discharge, and the full discharge and charge cathodes demonstrated that nitrogen functionalization triggered the formation of solid parasitic products that passivate the cathode surface, thus resulting in a poorer electrochemical performance. By contrast, functionalization with boron-containing groups demonstrated to be a more promising strategy due to minimized parasitic products, leading to lower oxygen reduction and evolution overpotentials with a concomitantly enhanced cell efficiency vs. the undoped cathodes. This resulted in a cycle life of 70 cycles at a relatively high current density of 0.1 mA cm−2 with a capacity cut-off of 0.5 mAh cm−2. Our study underscores that functionalization with heteroatoms simultaneously alters multiple characteristics of graphene-based materials, including their chemistry, texture and morphology, which in turn presents a critical impact on the electrochemical response of the resultant Na-O2 cells.

NiFe(CoFe)/silica and NiFe(CoFe)/alumina nanocomposites for the catalytic hydrogenation of CO2

The fumed SiO2 and Al2O3 oxides with a specific surface area of about 80 m2 g–1 were used for the synthesis of Ni(80)Fe(20)/SiO2, Co(93)Fe(7)/SiO2, Ni(80)Fe(20)/Al2O3 and Co(93)Fe(7)/Al2O3 nanocomposites, and numbers between brackets indicate the metal content in wt%, being 10 wt% of the mass of catalysts. Catalytically active bimetallic compositions (NiFe and CoFe) that modified the fumed oxides’ surface were prepared using the solvate-stimulated method with subsequent thermal decomposition and reduction of the metal oxides to corresponding metals with hydrogen. The catalysts were characterized using the TGA in dynamic hydrogen, nitrogen physisorption, and PXRD methods. The complete conversion of carbon dioxide is observed in the temperature range of 350–425 °C at the maximum methane yield of 72–84%. The long-time catalytic test demonstrates the high stability of the catalyst during 5 weeks of exposure to the reaction mixture. The yield of methane was decreased by 3–14% after 1–2 months of long-time testing.

Mercaptopropane-assisted synthesis of graphitic carbon-supported Pt nanoparticles for enhancing fuel cell start-stop performance

Although graphitic carbons, as a support for the cathode catalyst in proton exchange membrane fuel cells, have significant advantages in enhancing the corrosion resistance of the catalyst, the preparation of small-sized Pt particles on the graphitic carbon support often faces challenges due to its low porosity and lack of defect structures. Here, we report a mercaptopropane-assisted impregnation method to achieve size control of Pt nanoparticles on graphitic carbon. We show that mercaptopropane can coordinate with Pt during the impregnation process and transform into sulfur-doped carbon coatings through the subsequent thermal reduction process, which ensures the formation of small-sized Pt nanoparticles on graphitic carbon. Due to effective size control, the prepared cathode catalyst exhibited enhanced fuel cell performance compared to the catalyst prepared by the traditional impregnation method. We performed the accelerated stress test on the synthesized catalyst using the durability protocol recommended by the U.S. Department of Energy (DOE). After 5000 voltage cycles in the range of 1.0–1.5 V, the catalyst showed a negligible voltage loss of only 10 mV at a current density of 1.5 A·cm<sup>−2</sup>, meeting the DOE support durability target (30 mV).

Facile and scalable preparation of ultralight cobalt@graphene aerogel microspheres with strong and wide bandwidth microwave absorption

Cobalt@graphene aerogel microspheres (GCoAMs) with tunable porous structures are fabricated by using a unique spraying and crosslinking coagulation method. The graphene oxide (GO) and sodium alginate (SA) mixture aqueous dispersions were used for spraying. The cross-linking reaction occurs quickly between the carboxylic group of SA in the sprayed microdroplets and metal Co2+ in the collector bath, which fixes the microsphere shape and in-situ immobilizes the metal ion. After freeze-drying and the subsequent high-temperature thermal reduction, the ultralight GCoAMs are obtained. The pore structures of GCoAMs can be controlled by varying the GO/SA ratio. The GCoAMs exhibit strong and wide broadband microwave absorption due to its hierarchical porous structures and graphene/metal Co hybrid composition. At a GCoAMs loading content of 1.5 wt%, the minimal reflection loss reaches as high as −70.4 dB with a thin specimen thickness of 2.2 mm at 13.18 GHz and its effective absorption band achieves 5.65 GHz with a specimen thickness of 1.98 mm. At 2 wt% GCoAMs, the effective absorption band achieves 6.09 GHz with a specimen thickness of 2 mm, covering the whole Ku band. This work provides a novel, low-cost and easily scale-up method for preparing the lightweight and efficient microwave absorbers, which could be used in microwave telecommunication fields.

Fast and stable Na insertion/deinsertion in double-shell hollow MnO nanospheres

MnO has received much attention at the anode material for sodium storage due to its low cost, environmental friendliness, and non-toxicity. However, many MnO-based electrodes exhibit poor cyclic stability, and very limited attention has been paid to the sodium storage mechanism of MnO. Herein, we report a self-templating method to synthesize uniform MnO double-shell hollow nanospheres. By thermally annealing the Mn-based metal organic framework precursor, Mn2O3 double-shell hollow nanospheres has been synthesized via a possible Ostwald ripening process and MnO double-shell hollow nanospheres is obtained by a subsequent thermal reduction of Mn2O3. When used as the anode material for sodium storage, the as-prepared MnO demonstrate a reversible capability of 261 mAh g−1 at 0.2 A g−1 after 200 cycles. Furthermore, compared with solid MnO without a hollow interior, the MnO double-shell hollow nanospheres exhibit a more stable retention of 81 mA h g−1 at 5 A g−1 after 2000 cycles, and a better rate performance of 97 mA h g−1 at 10 A g−1. Surprisingly, the ex-situ XRD results reveal that the sodium storage process of MnO is governed mainly by insertion/deinsertion reactions, while the conversion between Mn and Na2O only takes place to a little extent. Such a hollow construction allows a more stable structural integrity granting enhanced long-term cycling stability.

Low temperature, area-selective atomic layer deposition of NiO and Ni

Nickel and nickel oxide are utilized within various device heterostructures for chemical sensing, solar cells, batteries, etc. Recently, the rising interest in realizing low-cost, flexible electronics to enable ubiquitous sensors and solar panels, next-generation displays, and improved human-machine interfaces has driven interest in the development of low-temperature fabrication processes for the integration of inorganic devices with polymeric substrates. Here, we report the low-temperature area-selective atomic layer deposition of Ni by reduction of preformed NiO. Area-selective deposition of NiO is performed at 100 °C using bis(N,N'-di-tert-butylacetamidinato) nickel(II) and water on SiO2 and polystyrene. NiO grows two-dimensionally and without nucleation delay on oxide substrates but not on SiNx or polystyrene, which require surface treatments to promote NiO nucleation. Additionally, prepatterned sp2 carbon-rich resists inhibit the nucleation of NiO, and in this way, carbon-free NiO may be patterned. Subsequent thermal reduction of NiO to Ni was investigated using H2 (50–80 m Torr) and thermally generated H-atoms (3 × 10−5 Torr chamber pressure). Due to the relatively high free surface energy of Ni metal, Ni films undergo dewetting at elevated temperatures when solid-state transport is enabled. Reduction of NiO to Ni is demonstrated at 100 °C and below using atomic hydrogen. In situ x-ray photoelectron spectroscopy is used to determine oxidation state and ex situ x-ray reflectivity and atomic force microscopy are used to probe the film thickness and surface morphology, respectively.

Improveament of multiple attenuation and optimized impedance gradient for excellent multilayer microwave absorbers derived from two-dimensional metal–organic frameworks

Low-dimensional carbon matrix magnetic nanocomposites exhibit expansive prospects as lightweight microwave absorbers due to their large specific surface area and multiple attenuation characteristics. The two-dimensional (2D) flaky MOF-derived porous nanocomposites are synthesized successfully by acid etching and subsequent thermal reduction. An in-depth study of composition and flaky porous structure shows that acid etching increases multiple interfaces and carbon defects, proving beneficial for improving multiple interfacial polarization and relaxation polarization loss. In addition, the generated ferromagnetic products (Ni4N, CoFe) are beneficial in improving the magnetic loss ability. More importantly, the multilayer impedance gradient design optimizes the impedance matching characteristic. As a result, the prepared bilayer absorbing coating exhibits excellent microwave absorption properties with an effective absorption bandwidth (EAB) of 6.32 GHz at a thickness of 2.5 mm with a filling amount less than 15 wt%. When the total thickness is 3 mm, it can exhibit the widest EAB of about 7.1 GHz and the minimum reflection loss (RLmin) value of about −54.5 dB. The RCS simulation shows that the multilayer coatings exhibit good microwave scattering and absorption ability under different pitching angles, proving potential candidates for excellent microwave absorbers.

Nanoarchitectonics of graphene oxide with functionalized cellulose nanocrystals achieving simultaneous dual connections and defect repair through catalytic graphitization for high thermal conductivity

Graphene, with an extremely high intrinsic thermal conductivity of 5300 W/mK, is of special interest to meet thermal requirements in future wearable and high-power electronic devices. Generally, microscopic graphene sheets can be built into a macroscopic material by using graphene oxide (GO) as the precursor. However, both the defects on the basal plane of GO sheets and the lack of connections at their boundaries induce massive scattering of phonons and a low thermal conductivity. Herein, we solve the problem through the nanoarchitectonics of GO with nano Fe3O4 functionalized cellulose nanocrystals (Fe–CNC). During the assembly process, Fe–CNC were compounded with GO homogeneously and formed a composite GO/Fe–CNC film with an aligned lamellar structure. A subsequent thermal reduction at 1500 °C resulted in the generation of Fe/Fe3C nanoparticles in the matrix of the reduced GO/Fe–CNC. During this process, the reduced GO (R-GO) sheets were dually connected by the Fe/Fe3C nanoparticles as well as the carbonized cellulose nanocrystals. Furthermore, the defects on the R-GO are repaired by Fe through a catalytic graphitization process. Thus, the scatterings of phonons at the adjacent sheet boundaries and on the basal plane of the R-GO sheets were reduced. A flexible and light weight composite film of reduced GO/Fe–CNC with a thermal conductivity of 1958.14 W/mK was obtained. The thermal conductivity is much higher than that of a pure R-GO film (388.72 W/mK) prepared under the same conditions. This assembly process achieved dual connections and defect repairs simultaneously and it provides an avenue for the design of graphene-based films with a high thermal conductivity.

Ni@rGO into nickel foam for composite polyethylene glycol and erythritol phase change materials

The exploitation of shape-stabilized composite phase change materials (CPCMs) with high solar-thermal conversion efficiency, thermal storage capacity and thermal conductivity has attractive prospects for solar energy utilization. In this work, reduced graphene oxide (rGO) nanosheets decorated with Ni nanoparticles (Ni@rGO) are successfully filled into the nickel foam (NF) skeletons by acidic graphene oxide solution impregnation and subsequent thermal reduction methods. The obtained NF/Ni@rGO supports with controllable Ni@rGO content are used as the carrier for loading polyethylene glycol (PEG) and erythritol (ET) to prepare CPCMs. The Ni@rGO hybridization enhances the interaction of the carrier framework with the PCM, which can effectively increase the PCM loading and prevent its leakage. As compared with bare NF supported CPCMs, the NF/Ni@rGO supported CPCMs have better shape stability, far higher thermal storage density, and better recyclability. The optimized CPCMs with PEG and ET show high latent enthalpies of 125.30 J·g−1 and 280.66 J·g−1, respectively. It is also found that the thermal conductivity of CPCMs is significantly improved to 0.9199 W·m−1K−1 for NF/Ni@rGO-10/PEG and 0.9146 W·m−1K−1 for NF/Ni@rGO-10/ET, which is 344 % and 35 % higher than that of PEG and ET, respectively. In addition, the decoration of Ni nanoparticles on the rGO support (i.e., NF/Ni@rGO-10) could further improve the thermal conductivity, solar-thermal conversion efficiency (95.74 %) and electro-thermal conversion efficiency (71.39 %) of CPCMs. This research furnishes the basis for the development of high performance CPCMs. Moreover, it has great potential and broad application prospects in the efficient utilization of solar energy and thermal management of electronic devices.

Improvement in long-term stability of field effect transistor biosensor in aqueous environments using a combination of silane and reduced graphene oxide coating

A field-effect transistor (FET) biosensor that can directly detect target molecules is a promising diagnostic tool for healthcare and medical applications. However, the immersion of FET sensors in aqueous physiological environments for the long-term stability might damage the insulating layer of silicon dioxide, resulting in the degradation of the sensor response reproducibility. In this study, to improve the durability of the sensor response for long-term immersion in aqueous solution, we examined the effectiveness of reduced graphene oxide (rGO) coating on the gate insulator of FET sensors. The rGO coating was applied to the gate surface of the FET biosensor modified with an amino-terminated self-assembled monolayer by two steps: deposition of graphene oxide (GO) dispersion onto the monolayer-modified surface and subsequent thermal reduction of GO. The transconductance of both GO-coated and rGO-coated FETs remained unchanged after incubation under physiological conditions, suggesting that graphene prevents cations in the electrolytes from invading the gate insulator of the FET. Furthermore, functionalizing the rGO-coated FET surface enabled specific detection of target molecule.

Facile fabrication of flame‐retardant and conductive cotton fabric via layer‐by‐layer assembly for human motion detection

AbstractFlexible piezoresistive pressure sensors have great application potential in many emerging fields such as electronic skin, artificial intelligence and human healthcare. However, most of the sensors are flammable, which will easily initiate fire hazard in case of short circuit. Herein, a flame‐retardant and conductive cotton fabric (CF) was fabricated for piezoresistive pressure sensor by layer‐by‐layer (LBL) assembly of branched polyethyleneimine (b‐PEI) modified halloysite nanotubes (HNTs), phytic acid (PA) and graphene oxide (GO) and the subsequent thermal reduction of GO. The composite coating layer endowed the obtained CF with excellent flame retardancy. The limiting oxygen index of the CF reached 32.72% and the char length after vertical burning test was only 3.8 cm, attributing to the physical barrier role of the HNTs and graphene nanosheets as well as the phosphorus‐nitrogen synergism between PA and b‐PEI. The CF‐based piezoresistive pressure sensor exhibited fast and accurate response, good signal stability and fatigue resistance (3000 loading‐unloading cycles) and was able to be applied for detecting human motions including pulse beat, pronunciation and various physical activities. The preparation method in this work is simple, and the piezoresistive pressure sensor shows great application prospect in the field of flexible electronics with high safety.

Robust Ti3C2Tx/RGO/ANFs hybrid aerogel with outstanding electromagnetic shielding performance and compression resilience

In this contribution, we demonstrated an efficient approach for constructing conductive aramid nanofibers based porous architectures by graphene oxide and Ti3C2Tx via freeze drying and subsequent thermal reduction. Specifically, the aramid nanofibers laid the foundation for mechanical enhancement and good electrical conductivity of Ti3C2Tx and RGO ensured outstanding electromagnetic shielding ability. The resultant Ti3C2Tx/RGO/ANFs hybrid aerogel presented a spongy structure, which was conducive to the dissipation of incident electromagnetic waves through multiple reflection and scattering. The electromagnetic shielding efficiency reached 54.8 dB in X-band (8.2–12.4 GHz) with 25 wt% loading content of Ti3C2Tx. When the addition amount of Ti3C2Tx was 5 wt%, the optimum compressive stress of Ti3C2Tx/RGO/ANFs hybrid aerogel reached 200 kPa under 70% strain with a relatively low density of 0.062 g/cm3. This work provided a feasible approach to fabricate robust hybrid aerogel with excellent electromagnetic shielding performance and compression resilience.

High performance H2 sensor based on rGO-wrapped SnO2–Pd porous hollow spheres

Hydrogen (H2) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO2–Pd porous hollow spheres composite (SnO2–Pd@rGO) for high performance H2 sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO2-based spheres with subsequent thermal reduction in H2 ambient. This sensor exhibited excellently selective H2 sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ∼8 to 0.1 ppm H2 in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H2 monitoring. Furthermore, this sensor demonstrated certain response to H2 at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions, the catalysis of the doped-PdOx, the relative hydrophobic surface from rGO, and the deoxygenation after H2 reduction.