3D Reduced Graphene Oxide Research Articles

Facile preparation of 3D graphene frameworks as functional modification platform for sensitive electrochemical detection of chloride ions

Multilayer graphene oxide(MGO) highly stacked nature restricts its application in the sensor field, and obtaining high-quality 3D graphene remains a significant challenge. Herein, we report the direct use of MGO to synthesize highly dispersed and rich ordered mesoporous 3D reduced graphene oxide frameworks(rGOFs) through a novel improved KOH activation method, which is based on the pre-treatment process of fully adsorbing and fixing the appropriate amount of K + by using the limited interlayer space of MGO and freeze-drying crystallization technology. Surprisingly, different from previous reports that only the micropores and individual macropores have been obtained by conventional KOH activation, we fully confirmed the dense and ordered mesoporous defects on the surface of rGOFs by SEM for the first time, as well as the multilayer stacked structure of rGOFs is in line with the typical 3D structure. Besides, rGOFs have the excellent properties of reduced graphene oxide (rGO) and a particular 3D framework structure, making it an excellent functionalized modification platform. In order to verify the performance of rGOFs as a framework platform, in which amination modification and small-size Ag NPs loading were successfully realized, the constructed Ag@rGOF-NH 2 /GCE sensor detects chloride ions over a wide linear concentration range of 5 μmol L −1 -10 μmol L −1 , with the detection limit as low as 0.1 μmol L −1 (S/N = 3). This work would not only open a new path to synthesize 3D graphene with excellent performance, and the concept of graphene frameworks nanomaterial is proposed for the first time, but also promotes its excellent performance as an ideal matrix platform for other nanomaterials in the field of electrochemical sensing.

Electromagnetic shielding performance of SiC/graphitic carbon-SiCN porous ceramic nanocomposites derived from catalyst assisted single-source-precursors

In this work, SiC nanowires and graphitic carbon (GC) including 2D reduced graphene oxide and graphene-liked ribbons modified polymer derived SiCN (SiC/GC-SiCN) porous ceramic monoliths were prepared via catalyst assisted single-source-precursor derived ceramic route. The inclusion of absorbents (e.g. graphitic carbon and SiC nanowires) significantly improved the electrical conductivity of the materials from 1.77 × 10−8 S/cm (pristine SiCN) to 0.56 S/cm. In turn, the electromagnetic interference shielding effectiveness (EMI SE) of the ceramic increased significantly from 4.0 dB to 19.2 dB. At the highest absorbent content, the SiC/GC-SiCN ceramics exhibit a high absorption power of 0.3 nW and an SE of 48.5 dB at thickness of 2 mm, which means more than 99.998 % of the EM wave is blocked. This work finds new avenue for the design of advanced electromagnetic shielding materials possessing strong absorption capability.

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

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

Effective and selective removal of organic pollutants from aqueous solutions using 1D hydroxyapatite-decorated 2D reduced graphene oxide nanocomposite

The efficient and selective removal of toxic dye molecules from water/surface water remains a problematic task, owing to their high water solubility and low biodegradability. We fabricated the hydroxyapatite-decorated reduced graphene oxide (HA@rGO) nanocomposites via a simple hydrothermal process and used them as efficient adsorbents for the diazo dyes removal. In the batch experiments, the resultant HA@rGO nanocomposites exhibited fast and excellent removal performance for Trypan blue and Congo red dye molecules in a wide pH range and the maximum adsorption efficiencies of 146.51 and 150.09 mg/g, respectively. Several characterization analysis results demonstrated that the removal performance of the HA@rGO nanocomposites for the toxic dyes was mainly driven by electrostatic, hydrophobic, π–π interactions, and H-bonding between the adsorbents and dye molecules in the aqueous solution. Ubiquitous co-anions have significant influence on the dye removal performance of the HA@rGO nanocomposites because of the higher ionic radius and electronegativity. After adsorption, the exhausted HA@rGO nanocomposites could be regenerated in alkaline solution and reused throughout five successive adsorption–desorption cycles. We believe that the adsorbent fabricated in this work can be effectively used to remove toxic diazo dye molecules from aqueous media.

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

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

A Fishing‐Net‐Like 3D Host for Robust and Ultrahigh‐Rate Lithium Metal Anodes

Constructing an architectural host is demonstrated to be an effective strategy for long-life lithium metal anodes (LMAs). Herein, an integrated 3D host for stable and ultrahigh-rate LMAs is developed by a binary highly conductive network of 2D reduced graphene oxide (rGO) and 1D carbon nanofibers (CNF) anchored with 0D ultrasmall MgZnO nanoparticles (MgZnO/CNF-rGO). A facile net-fishing strategy is proposed to combine the rGO nanosheets with free-standing CNF matrix as interconnected paths for fast electron transport. Notably, serving as Li nucleation sites, the superlithiophilic MgZnO nanoparticles are uniformly distributed and tightly contacted with the conductive matrix without agglomeration due to the rGO confinement. Such a delicate nanoscale combination guarantees the effective transportation and uniform deposition of Li-ions in the inner surface of the host. The symmetric cell of Li@MgZnO/CNF-rGO exhibits a long lifespan above 1450 cycles under an ultrahigh current density of 50mAcm-2 with an areal capacity of 1.0mAhcm-2 . Impressively, it also delivers a high reversible capacity of 10mAhcm-2 at 50mAcm-2 . This work offers an avenue to promise the prospect for practical LMAs working under high rates and capacities.

1D Ti-based H2Ti12O25 nanorod @2D RGO sheet composite as high-power anode for long-life Li-ion battery

ABSTRACT The increasing incompatibility for LIBs between high-rate capability and high specific capacity, except for its energy density, stimulates the research of new electrode materials. In order to obtain the superior power properties of LIBs, seeking new anode materials with the above merits is vital. Herein, a new 1D Ti-based H2Ti12O25 nanorod @2D RGO (reduced graphene oxide) sheet (H2Ti12O25/RGO) composite structure is designed as high-power anode for long-life li-ion battery, which can achieve high-capacity, and high-rate property at the same time. H2Ti12O25 nanorods, bonded on RGO flakes, is synthesized by mean of in-situ structure transformation during solvothermal/hydrothermal reaction processes. To be specific, except for the safety performance, the H2Ti12O25/RGO electrode unfolds an exceptionally better rate-capacity performance, namely, high reversible capacity up to 260 mA h g−1 at 0.5 C and 123, 114 and 101 mA h g−1 at high rate of 20 C, 30 C and 50 C, respectively. Importantly, the 750th discharge capacity still could be maintained at 105.3 mA h g−1 at 30 C. The outstanding properties can be ascribed to the synergistic interaction between H2Ti12O25 nanorod and RGO sheets and its multi-dimensional composite structure which makes the faster electronic and ionic conductivity of 1D-H2Ti12O25@2D-RGO achieved.

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

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

Self‐Calibrated, Sensitive, and Flexible Temperature Sensor Based on 3D Chemically Modified Graphene Hydrogel

AbstractDuring the long‐term operation of temperature sensors, periodical calibration is required to achieve accurate readings, which usually requires bulky and costly heating facilities for calibration. Herein, a new kind of self‐calibrated thermistors using embedded microheaters as a self‐heating platform are proposed for in situ, convenient, cost‐effective, and fast self‐calibration. Furthermore, the thermal sensing properties of 3D reduced graphene oxide hydrogel (RGOH) is explored for the first time based on this microheater platform. It is found that the a 3D sulfonated RGOH (S‐RGOH) based thermistor displays high sensitivity (2.04% K−1), extraordinary resolution (0.2 °C), a broad detection range (26–101 °C), good repeatability, and stability. The thermal sensitivity of S‐RGOH is far superior to that of pristine RGOH, revealing the remarkable role of chemical modification in enhancing temperature sensing performance. In addition to self‐calibration, the microheaters are also used for characterizing temperature‐dependent properties and thermal annealing of S‐RGOH in situ. The thermal sensing mechanism is proposed and the high sensitivity is discussed by considering the abundant functional groups, defects, and 3D porous structure of S‐RGOH. The flexible S‐RGOH thermistor fabricated on a liquid crystal polymer substrate is immune to mechanical flexion, allowing for various practical applications in future wearable electronics.

Theoretical guidance for the construction of electron-rich reaction microcenters on C–O–Fe bridges for enhanced Fenton-like degradation of tetracycline hydrochloride

The construction of dual electron reaction centers is an attractive strategy to accelerate the rate-limiting step in Fenton-like catalyst. In this work, we constructed the dual electron reaction centers and electron transport path over C–O–Fe bridges connected by graphene oxide (GO) and Fe3O4 through density functional theory (DFT). The calculations show that there is a strong interaction of C–O–Fe between GO and Fe3O4, and electrons around C would transfer to Fe along C–O–Fe linkages and the electron-rich reaction microcenters are generated around Fe. Based on it, Fenton-like catalyst of ultra-small Fe3O4 (less than 10 nm) loaded on 3D reduced graphene oxide (rGO) (composite denoted as rGF) was successfully prepared. Characterization analyses have demonstrated that C–O–Fe bonds exist in rGF and CV test confirmed the cross-linked structure implemented by C–O–Fe is thermodynamically beneficial for electrons transport to Fe which is responsible for the regeneration of Fe(II). When the weight ratios of GO to Fe3O4 reach 5%, rGF-5, the optimized composite displays superior Fenton-like performance that the removal efficiencies of tetracycline hydrochloride (TCH) are 98.7% within 60 min and 96.1% within 90 min, with the initial pH 4.5 and pH 6.7, respectively. The excellent cyclic stability of rGF-5 further verifies the structure of electron-rich reaction microcenters on C–O–Fe bond bridges is well established to ensure that Fenton-like reactions continue to occur efficiently. The results of mass spectrometry indicate that products with m/z = 114 converted from TCH (m/z = 445) accounted for 87% at 60 min. This work not only achieves a way to construct high-performance heterogeneous Fenton-like catalysts for degradation of antibiotics, but also provides a new insight for designing various efficient catalysts based on the theoretical guidance.

In situ integrated 2D reduced graphene oxide nanosheets with MoSSe for hydrogen evolution reaction and supercapacitor application

The electrochemical hydrogen evolution reaction (HER) and supercapacitor are regarded as promising tools to meet the existing energy demand around the world. The non-noble metals such as Mo, W based dichalcogenide electrocatalysts are considered as highly catalytic active materials due to its chemical stability, active edge sites and tunable electronic structure. Here, we have prepared different Mo and W based dichalcogenides such as molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2), molybdenum sulfoselenide (MoSSe), tungsten disulfide (WS2), tungsten diselenide (WSe2) and tungsten sulfoselenide (WSSe) nanostructures as a bifunctional electrode material for HER and supercapacitor application. Further the incorporation of two dimensional (2D) nanosheets such as reduced graphene oxide (rGO) into MoSSe (MoSSe/rGO) or WSSe (WSSe/rGO) has altered the electrically conducting active edge sites to ease out the adsorption of hydrogen. Moreover the obtained composite materials were prepared by simple one pot hydrothermal method and characterized by X-ray diffraction analysis (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) mapping techniques. In HER activity studies, MoSSe/rGO shows a minimum overpotential of 285 mV at 10 mA cm−2 current density with the Tafel slope of 98 mV dec−1. Besides, good cyclic stability property upto 1000 cycles was observed. In supercapacitor studies, MoSSe/rGO composite shows the specific capacitance of 373 Fg−1 at 1 Ag−1 current density. The synergistic effect between MoSSe and rGO nanosheets via electrostatic interaction makes the composite material as strong. As a result, during the cyclic study, among different Mo and W based dichalcogenides, MoSSe/rGO composite electrode shows high stability towards HER and supercapacitor.

β-Cyclodextrin functionalized 3D reduced graphene oxide composite-based electrochemical sensor for the sensitive detection of dopamine.

A three-dimensional reduced graphene oxide nanomaterial with β-cyclodextrin modified glassy carbon electrode (3D-rGO/β-CD/GCE) was constructed and used to detect the electrochemical behavior of dopamine (DA). The nanocomposite materials were characterized by scanning electron microscopy (SEM), infrared spectrometry (FT-IR), Raman spectrogram and thermogravimetric analysis (TGA), which showed that β-CD was well modified on 3D graphene with a porous structure. The electrochemical properties of different modified electrodes were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), proving the highest electron transfer rate of the 3D-rGO/β-CD modified electrode. The experimental conditions such as scan rate, pH, enrichment time and layer thickness were optimized. Under the best experimental conditions, DA was detected by differential pulse voltammetry (DPV) by 3D-rGO/β-CD/GCE with excellent electrocatalytic ability and satisfactory recognition ability, resulting in a wide linear range of 0.5–100 μM and a low detection limit (LOD) of 0.013 μM. The modified electrode based on 3D-rGO/β-CD nanocomposites is promising in the field of electrochemical sensors due to its high sensitivity and other excellent properties.

One-Pot Synthesis of Pt-Pd Nanospheres Anchored in 2D-Reduced Graphene Oxide Sheets for Electrocatalytic Methanol Oxidation

Recently, direct methanol fuel cells (DMFCs) have been identified as suitable alternatives for efficient energy conversion and pollution-free technology. This study reports the preparation of binary platinumpalladium (Pt-Pd) nanospheres anchored on reduced graphene oxide (rGO) sheets (Pt-Pd/rGO sheets) using a wet chemical technique. The structural and morphological features were analyzed using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman microscope and Fourier transform infrared (FTIR) spectroscopy. The homogeneous anchored Pt-Pd nanospheres with an average size of 3.85 nm were deposited on to the surface of rGO sheets. Methanol oxidation studies were analyzed through a simple drop coating method using a glassy carbon electrode (GCE). The methanol oxidation performance of the Pt-Pd/rGO nanospheres coated GCE was higher than that of the rGO sheets coated with a single metal (Pt or Pd). The concordant integration of the Pt and Pd nanospheres/rGO-interface improved performance.

Ruthenium nanoparticles supported on carbon-based nanoallotropes as co-catalyst to enhance the photocatalytic hydrogen evolution activity of carbon nitride

Development of competent and cost-effective materials for hydrogen evolution reaction (HER) has been attracting great attention since hydrogen is hailed as a promising environmentally friendly energy source to reduce the greenhouse emissions. Herein, Ru(0) nanoparticles (RuNPs) have been stabilized onto the surface of four different conducting carbon nanomaterials (CNMs) from 0D to 3D, such as 0D carbon nanohorns (CNH), 1D single-walled carbon nanotubes (CNTs), 2D reduced graphene oxide (rGO) and 3D graphite (GP), for their use in the photocatalytic HER. For this aim, the resulting RuNP@CNMs where physically mixed with mesoporous graphitic carbon nitride (mpg-CN) in an optimum composition ratio to maximize the photocatalytic HER activity. Notably, the resulting four hybrid RuNPs@CNM/mpg-CN materials showed an outstanding increase in the hydrogen evolution reaction (HER) when compared with the pristine mesoporous graphitic carbon nitride without co-catalyst. A comparison on the photocatalytic activity of the four hybrid RuNPs@CNMs physically mixed with mpg-CN and a deep study on the fate of the nanohybrids after catalysis are presented.

Investigation of polymer-derived Si\u2013(B)\u2013C\u2013N ceramic/reduced graphene oxide composite systems as active catalysts towards the hydrogen evolution reaction

Hydrogen Evolution Reaction (HER) is an attractive technology for chemical conversion of energy. Replacement of platinum with inexpensive and stable electrocatalysts remains a major bottleneck hampering large-scale hydrogen production by using clean and renewable energy sources. Here, we report electrocatalytically active and ultra-stable Polymer-Derived Ceramics towards HER. We successfully prepared ultrathin silicon and carbon (Si–C) based ceramic systems supported on electrically conducting 2D reduced graphene oxide (rGO) nanosheets with promising HER activity by varying the nature and the composition of the ceramic with the inclusion of nitrogen, boron and oxygen. Our results suggest that oxygen-enriched Si-B-C-N/rGO composites (O-SiBCN/rGO) display the strongest catalytic activity leading to an onset potential and a Tafel slope of − 340 mV and ~ 120 mV dec−1 respectively. O-SiBCN/rGO electrodes display stability over 170 h with minimal increase of 14% of the overpotential compared to ~ 1700% for commercial platinum nanoparticles. Our study provides new insights on the performance of ceramics as affordable and robust HER catalysts calling for further exploration of the electrocatalytic activity of such unconventional materials.

The Dual Capacity Contribution Mechanism of SnSb‐Anchored Nitrogen‐Doped 3D Reduced Graphene Oxide Enhances the Performance of Sodium‐Ion Batteries

AbstractNanoscale SnSb alloys exhibit lower expansion rates and outstanding electrochemical properties, owing to the synergy between Sn and Sb for anode materials of sodium‐ion batteries. However, nanomaterials with a high surface energy tend to aggregate and form larger secondary particles, limiting their further application. Herein, SnSb nanoparticles are prepared and distributed in three‐dimensional networks of N‐doped reduced graphene oxide (3D‐rNGO), which plays a crucial role in inhibiting the agglomeration of SnSb nanoparticles, thereby promoting the capacitive contribution of surface drive. More importantly, the three‐dimensional structure has a high specific surface area and the active region introduced by N doping can contact and adsorb more sodium ions as part of the electrochemical behavior, making the SnSb/3D‐rNGO anode not only contribute capacity through a diffusion process, but also provide a capacitive contribution through a surface‐driven mechanism. The results of the electrochemical analysis showed that SnSb/3D‐rNGO, as the anode of a sodium‐ion battery, exhibits a high specific capacity of 1169.6 mAh g−1, a reversible capacity of 55 % at 0.1 C, and maintains a capacity of 479.3 mAh g−1 after 200 cycles. It is suitable for energy storage precisely because of the double capacity contribution mechanism.

Fabrication of a High-Energy Flexible All-Solid-State Supercapacitor Using Pseudocapacitive 2D-Ti3C2Tx-MXene and Battery-Type Reduced Graphene Oxide/Nickel-Cobalt Bimetal Oxide Electrode Materials.

Owing to excellent metallic conductivity, hydrophilic surfaces, and surface redox properties, a two-dimensional (2D) metal carbide of Ti3C2Tx-MXene could serve as a promising pseudocapacitive electrode material for energy storage devices. Meanwhile, the 2D reduced graphene oxide (rGO) combining with the hierarchical cubic spinel nickel-cobalt bimetal oxide (NiCo2O4) nanospikes could control ion diffusion for charge storage, thereby facilitating the improvement of the energy density of a supercapacitor. As per the strategy, the pseudocapacitive 2D Ti3C2Tx was loaded on a flexible acid-treated carbon fiber (ACF) backbone to prepare a Ti3C2Tx/ACF negative electrode by a convenient drop-casting method. Meanwhile, 2D rGO was deposited on ACF by a simple dip-dry process, which was further decorated by the spinel NiCo2O4 nanospikes using a hydrothermal method to obtain a NiCo2O4@rGO/ACF positive electrode. The fabricated Ti3C2Tx/ACF electrode exhibited an excellent specific capacitance of 246.9 F/g (197.5 mF/cm2) at 4 mA/cm2 along with 96.7% capacity retention over 5000 charge/discharge cycles, whereas the NiCo2O4@rGO/ACF electrode showed a specific capacitance of 1487 F/g (458.3 mA h/g) at 3 mA/cm2 with a cycling stability of 88.2% over 10 000 charge/discharge cycles. As a result, a flexible all-solid-state hybrid supercapacitor (FHSC) device using the pseudocapacitive Ti3C2Tx/ACF on the negative side with a widespread voltage window and the battery-type NiCo2O4@rGO/ACF on the positive side with high electrochemical activity delivered an excellent volumetric capacitance of 2.32 F/cm3 (141.9 F/g) at a current density of 5 mA/cm2 with a high-energy density of 44.36 Wh/kg (0.72 mWh/cm3) at a power density of 985 W/kg (16.13 mW/cm3) along with a cycling stability of 90.48% over 4500 charge/discharge cycles. Therefore, the pseudocapacitive 2D Ti3C2Tx/ACF negative electrode could replace carbon-based electrodes and a combination of it with the battery-type NiCo2O4@rGO/ACF positive electrode should be a promising way to step up the energy density of a supercapacitor.

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

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

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

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

A novel three-dimensional Ag nanoparticles/reduced graphene oxide microtubular field effect transistor sensor for NO2 detections

A novel three-dimensional (3D) microtubular NO2 field effect transistor (FET) sensor has been fabricated from 2D reduced graphene oxide (rGO) nanosheets decorated with Ag nanoparticles, by applying the self-roll-up technique. The electrical properties of 2D and 3D Ag NP/rGO FET sensors have been investigated and compared. Finally, the performance of the 3D sensors has been demonstrated, where the preliminary results show that our 3D Ag NP/rGO FET NO2 sensor exhibits a relatively fast response (response time of 116 s) to 20 parts per million NO2 with a response of 4.92% at room temperature at zero bias voltage and 2 V source–drain bias voltage. Moreover, characteristics of our 3D Ag NP/rGO FET sensors, e.g. response, response and recovery times, have been demonstrated to be tuned by adjusting the applied source–drain and gate biases. Compared to the 2D geometry, our 3D geometry occupies less device area, but with the same sensing area. This study provides a new way to optimize sensing device performance, and promotes its development for miniaturized and integrated gas-sensing applications for indoor health and safety detection, outdoor environmental monitoring, industrial pollution monitoring and beyond.