As a simple and versatile method, diffusion driven Layer-by-Layer assembly (dd-LbL) is developed to assemble graphene oxide (GO) into three-dimensional (3D) structure. The assembled GO macrostructure ...can be reduced through a hydrothermal treatment and used as a high volumetric capacitance electrode in supercapacitors. In this report we use rGO framework created from dd-LbL as a scaffold for in situ polymerization of aniline within the pores of the framework to form rGO/polyaniline (rGO/PANI) composite. The rGO/PANI composite affords a robust and porous structure, which facilitates electrolyte diffusion and exhibits excellent electrochemical performance as binder-free electrodes in a sandwich-configuration supercapacitor. Combining electric double layer capacitance and pseudo-capacitance, rGO/PANI electrodes exhibit a specific capacitance of 438.8 F g−1 at discharge rate of 5 mA (mass of electrodes were 10.0 mg, 0.5 A g−1) in 1 mol L−1 H2SO4 electrolyte; furthermore, the generated PANI nanoparticles in rGO template achieve a higher capacitance of 763 F g−1. The rGO/PANI composite electrodes also show an improved recyclability, 76.5% of capacitance retains after recycled 2000 times.
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•3D porous rGO is prepared by diffusion driven layer-by-layer assembly.•Polyaniline (PANI) nanoparticles are in-situ grown within the pores of 3D rGO.•As-prepared rGO/PANI was used as binder-free electrodes for supercapacitor.•The rGO/PANI exhibits capacitance of 438.8 F g−1 at 0.5 A g−1 in 1 M H2SO4.•PANI particles achieve a higher capacitance of 763 F g−1 at 0.5 A g−1.
The interaction between host and microorganism widely affects the immune and metabolic status. Indole and its derivatives are metabolites produced by the metabolism of tryptophan catalyzed by ...intestinal microorganisms. By activating nuclear receptors, regulating intestinal hormones, and affecting the biological effects of bacteria as signaling molecules, indole and its derivatives maintain intestinal homeostasis and impact liver metabolism and the immune response, which shows good therapeutic prospects. We reviewed recent studies on indole and its derivatives, including related metabolism, the influence of diets and intestinal commensal bacteria, and the targets and mechanisms in pathological conditions, especially progress in therapeutic strategies. New research insights into indoles will facilitate a better understanding of their druggability and application in intestinal and liver diseases.
Wireless traffic volume detectors play a critical role for measuring the traffic-flow in a real-time for current Intelligent Traffic System. However, as a battery-operated electronic device, ...regularly replacing battery remains a great challenge, especially in the remote area and wide distribution. Here, we report a self-powered active wireless traffic volume sensor by using a rotating-disk-based hybridized nanogenerator of triboelectric nanogenerator and electromagnetic generator as the sustainable power source. Operated at a rotating rate of 1000 rpm, the device delivered an output power of 17.5 mW, corresponding to a volume power density of 55.7 W/m3 (P d = P/V, see Supporting Information for detailed calculation) at a loading resistance of 700 Ω. The hybridized nanogenerator was demonstrated to effectively harvest energy from wind generated by a moving vehicle through the tunnel. And the delivered power is capable of triggering a counter via a wireless transmitter for real-time monitoring the traffic volume in the tunnel. This study further expands the applications of triboelectric nanogenerators for high-performance ambient mechanical energy harvesting and as sustainable power sources for driving wireless traffic volume sensors.
With unique water-repellent and self-cleaning properties, engineering metallic materials with superhydrophobicity endows them with greatly enhanced corrosion resistance. Herein, a facile and ...controllable one-step electrodeposition approach was employed to fabricate a superhydrophobic surface (SHPS) on an aluminum (Al) substrate as a barrier against corrosion media. The wettability, morphology, and chemical composition of the consequent SHPS were characterized by contact angle (CA), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDS), respectively. The anti-contamination and anticorrosion behaviors of the resultant SHPS were investigated by self-cleaning test, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The electrochemical results indicate that the resultant SHPS possessed greatly enhanced corrosion resistance, and were able to reduce the corrosion of a bare Al surface, with an inhibition efficiency of 99.96%. Furthermore, the as-fabricated SHPS maintained excellent durability and stability after air exposure, deionized water immersion, and 3.5 wt% NaCl solution immersion. We believe that SHPS fabricated by a versatile one-step electrodeposition approach would make it possible to develop engineering materials with durable self-cleaning and anticorrosion properties for use in rugged environments.
A facile one-step electrodeposition method was used to fabricate a hierarchical papillae-covered SHPS on an Al substrate with enhanced corrosion resistance (corrosion inhibition efficiency ~99.96%) and lotus-like self-cleaning effect.
Contact-electrification is a universal effect for all existing materials, but it still lacks a quantitative materials database to systematically understand its scientific mechanisms. Using an ...established measurement method, this study quantifies the triboelectric charge densities of nearly 30 inorganic nonmetallic materials. From the matrix of their triboelectric charge densities and band structures, it is found that the triboelectric output is strongly related to the work functions of the materials. Our study verifies that contact-electrification is an electronic quantum transition effect under ambient conditions. The basic driving force for contact-electrification is that electrons seek to fill the lowest available states once two materials are forced to reach atomically close distance so that electron transitions are possible through strongly overlapping electron wave functions. We hope that the quantified series could serve as a textbook standard and a fundamental database for scientific research, practical manufacturing, and engineering.
A novel triboelectric nanogenerator (TENG) is designed, based on flexible and transparent vertical‐strip arrays, for environmental wind‐energy harvesting. Given the low cost, simple structure, and ...wide applicability, the TENGs present a green alternative to traditional methods used for large‐scale wind‐energy harvesting.
As a member of the lead-halide perovskite family, inorganic perovskite CsPbBr3 exhibits excellent optical and electrical properties with higher stability to the environment. However, former efforts ...to obtain large-size CsPbBr3 single crystals with satisfactory quality using low temperature solution methods reached limited results. In this work, we have studied the growth of CsPbBr3 crystals using the antisolvent vapor-assisted crystallization (AVC) method. By adjusting the mole ratio of PbBr2 and CsBr, the phase diagram of the final products is acquired. Five regions are identified, including the Cs4PbBr6 single phase region, Cs4PbBr6 and CsPbBr3 two phases region, CsPbBr3 single phase region, CsPbBr3 and PbBr2·2(CH3)2SO metastable two phases region, and CsPbBr3 and PbBr2·2(CH3)2SO two phases region. Three methods are adopted to improve the size and crystalline quality of CsPbBr3. The growth rate is effectively tailored by diluting the antisolvent MeOH solution using DMSO to reduce the MeOH vapor pressure. Centimeter-size bright CsPbBr3 crystals have been obtained. The room temperature bandgap of CsPbBr3 is estimated at ∼2.29 eV by the transmission spectra. The photoluminescence spectra show two strong emission peaks, located at 530 and 555 nm, respectively, which are related to the free and bond excitons. The resistivity is as large as 2.1 × 109 Ω·cm. Hall effect measurements demonstrate the CsPbBr3 is p-type conductivity with a hole carrier concentration of 4.55 × 107 cm–3 and the mobility of 143 cm2 V–1 s–1. The resulting Au/CsPbBr3/Au device exhibits strong photoresponse to optical light, with an on–off ratio of two orders under a light emitting diode (∼1 mW/cm2) with a wavelength of 365–420 nm. Our research would shed more light on the growth and the photoresponse properties of CsPbBr3 crystals.
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•Robust superhydrophobic composite coating was fabricated via spraying method.•The coating possesses self-cleaning, anti-fouling, and liquid-repellency properties.•The coating ...exhibits sustainable corrosion resistance and long-term weatherability.•Superhydrophobicity was maintained after 150 tape-peeling and 80 abrasion cycles.
In this paper, a superhydrophobic composite coating was developed employing epoxy resin (EP), polydimethylsiloxane (PDMS), and hexadecyltrimethoxysilane (HDTMS) functionalized Al2O3 nanoparticles as raw materials through a versatile and easily-scalable spray-coating technique. The water contact angle (WCA) and sliding angle (SA) of the designed superhydrophobic composite coating were 154.1 ± 0.7°and 3.5 ± 0.3°, respectively. The superhydrophobic composite coating features Cassie-Baxter phase contact, liquids repellency, anti-fouling, and self-cleaning properties for various liquid and solid contaminants. Compared with bare Q235 carbon steel, the charge transfer resistance (Rct) value of superhydrophobic composite coating immersed in the 3.5 wt. % NaCl solution can be remarkably enhanced by more than 7 orders of magnitudes with a corrosion inhibition efficiency of 99.99%. The coating maintain its superhydrophobicity, ultra-low adhesion force, and sustainable corrosion resistance even suffering 150 tape-peeling and 80 abrasion cycles. The improved durable mechanical robustness and interfacial bonding force can be attributed to the cross-linked and polymerized three-dimensional network micro-nano hierarchical structures formed by the combination of EP, PDMS, and embedded Al2O3@HDTMS nanoparticles. Besides, the accelerated salt-spray corrosion test (480 h) and atmospheric corrosion exposure (100 days) of the coating demonstrated superior anti-corrosion performance in both laboratory and real-world corrosive environments.
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•Superhydrophobic ZnO@STA@PDMS coating was designed via spraying method.•The coating possesses fluorine-free, substrate-independent and robust properties.•EIS and polarization results ...present greatly enhanced corrosion resistance.•A new salt-deliquesce self-coalescence anti-corrosion mechanism was proposed.•The coating provides promising applications in marine submerged and atmospheric zones.
Biomimetic superhydrophobicity endows various substrates with amazing multi-functional properties. However, fragile hierarchical structures, fluorine-containing chemicals usage, and strict requirements for substrate scopes remain thorny challenges. Herein, we constructed a mechanical robust superhydrophobic ZnO@STA@PDMS coating with fluorine-free reagents through wide-applicable and substrate-independent spray-coating method. Field-emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and contact angle meter were used to assess the surface micro-nano structures, chemical compositions, thermal stability and wettability variations. The corrosion resistance of the developed superhydrophobic ZnO@STA@PDMS coating was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The corrosion current density (Icorr) of the substrate reduces by two orders of magnitude after being spray-coated with superhydrophobic ZnO@STA@PDMS coating, indicating excellent corrosion resistance in marine submerged zone. In simulated marine atmospheric conditions with high relative humidity, the salt-deliquesce behaviors of single and double NaCl particles on bare and coated Q235 carbon steel surfaces were recorded. In a high humidity atmospheric environment, the instantaneous salt-deliquesce self-coalescence phenomena provides a new type of anti-corrosion mechanism. Furthermore, the prepared superhydrophobic coating can withstand more than 30 tape-peeling cycles and 400 cm abrasion distance, demonstrating good mechanical stability in prospective real-world applications.
MXenes have exhibited potential for application in flexible devices owing to their remarkable electronic, optical, and mechanical properties. Printing strategies have emerged as a facile route for ...additive manufacturing of MXene‐based devices, which relies on the rational design of functional inks with appropriate rheological properties. Herein, aqueous MXene/xanthan gum hybrid inks with tunable viscosity, excellent printability, and long‐term stability are designed. Screen‐printed flexible MXene films using such hybrid inks exhibit a high conductivity up to 4.8 × 104 S m−1, which is suitable to construct multifunctional devices mainly including electromagnetic shielding, Joule heaters, and piezoresistive sensors. The average electromagnetic interference (EMI) shielding value can reach to 40.1 dB. In the Joule heater, the heating rate of printed MXene film can reach 20 °C s−1 under a driving voltage of 4 V, with a highest steady‐state temperature of 130.8 °C. An MXene‐based piezoresistive sensor prepared by the printing interdigital electrode also presents good sensing performance with a short response time of 130 ms and wide pressure region up to 30 kPa. As a result, screen‐printed MXene film exhibits reinforced multifunctional performance, which is promising for application in the next‐generation of intelligent and wearable devices.
Aqueous MXene/xanthan gum hybrid inks with tunable viscosity, excellent printability, and long‐term stability are formulated for screen printing flexible devices. The hybrid inks can be screen‐printed into diverse patterns with high conductivity and excellent mechanical flexibility, all contributing to the fabrication of multifunctional devices with outstanding EMI, Joule heater, and piezoresistive sensor performances.
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