Highlights
The sensors displayed high sensitivity (8962.7), fast response time (60 ms), outstanding stability and durability (> 10,000 cycles) and widely workable stretching range (0–160%).
A ...theoretical approach was used to analyze mechanical property, and a model based on tunneling theory was modified to describe the relative change of resistance.
Two equations were proposed and offered an effective but simple approach to analyze the change of number of conductive paths and distance of adjacent conductive particles.
In recently years, high-performance wearable strain sensors have attracted great attention in academic and industrial. Herein, a conductive polymer composite of electrospun thermoplastic polyurethane (TPU) fibrous film matrix-embedded carbon black (CB) particles with adjustable scaffold network was fabricated for high-sensitive strain sensor. This work indicated the influence of stereoscopic scaffold network structure built under various rotating speeds of collection device in electrospinning process on the electrical response of TPU/CB strain sensor. This structure makes the sensor exhibit combined characters of high sensitivity under stretching strain (gauge factor of 8962.7 at 155% strain), fast response time (60 ms), outstanding stability and durability (> 10,000 cycles) and a widely workable stretching range (0–160%). This high-performance, wearable, flexible strain sensor has a broad vision of application such as intelligent terminals, electrical skins, voice measurement and human motion monitoring. Moreover, a theoretical approach was used to analyze mechanical property and a model based on tunneling theory was modified to describe the relative change of resistance upon the applied strain. Meanwhile, two equations based from this model were first proposed and offered an effective but simple approach to analyze the change of number of conductive paths and distance of adjacent conductive particles.
The oxygen evolution reaction (OER) is the bottleneck that limits the energy efficiency of water-splitting. The process involves four electrons' transfer and the generation of triplet state O
from ...singlet state species (OH
or H
O). Recently, explicit spin selection was described as a possible way to promote OER in alkaline conditions, but the specific spin-polarized kinetics remains unclear. Here, we report that by using ferromagnetic ordered catalysts as the spin polarizer for spin selection under a constant magnetic field, the OER can be enhanced. However, it does not applicable to non-ferromagnetic catalysts. We found that the spin polarization occurs at the first electron transfer step in OER, where coherent spin exchange happens between the ferromagnetic catalyst and the adsorbed oxygen species with fast kinetics, under the principle of spin angular momentum conservation. In the next three electron transfer steps, as the adsorbed O species adopt fixed spin direction, the OER electrons need to follow the Hund rule and Pauling exclusion principle, thus to carry out spin polarization spontaneously and finally lead to the generation of triplet state O
. Here, we showcase spin-polarized kinetics of oxygen evolution reaction, which gives references in the understanding and design of spin-dependent catalysts.
Hierarchical engineering of suitable dielectric‐magnetic multicomponents shows good performance for microwave absorbers, but still face bottlenecks. Herein, hierarchical double‐shelled nanotubes ...(DSNTs), in which the inner magnetic tubular subunits are assembled by magnetic‐heteroatomic components through cation‐exchange reactions, and the outer dielectric MnO2 nanosheets strengthen the synergistic interactions between confined heterogeneous interfaces are ingeniously designed and constructed. Hetero‐interfaces induced polarization is proposed to investigate the interfacial relaxation mechanism, and magnetic loss, closely related to the micrometer‐scale magnetic units, is mainly clarified by the magnetic interaction composed of magnetic coupling and magnetic diffraction; both of them are clearly confirmed by Lorentz off‐axis electron holography. The obtained hierarchical DSNTs demonstrate efficient microwave absorption with an optimal reflection loss of −54.7 dB and qualified absorption bandwidth of 9.5 GHz owing to desirable heterogeneous interfaces, multiple magnetic heteroatomic components and hollow hierarchical microstructures. This strategy inspires a generalized methodology for the engineering of hollow hierarchical configurations with multishells, the combination of proposed hetero‐interfaces induced polarization and microscale magnetic interaction broadens the dielectric‐magnetic synergistic mechanism of the topography–performance relationship for microwave absorption materials.
In this work, the authors propose an ion exchange‐pyrolysis‐hydrothermal strategy to construct hierarchical double‐shelled nanotubes, in which inner magnetic tubular subunits are assembled by magnetic‐heteroatomic components and outer dielectric MnO2 nanosheets are randomly packed on the surface.
Solar steam generation is an emerging strategy for water desalination using renewable solar energy and seawater resources. In order to convert solar energy into heat for seawater evaporation, we ...developed a bi-layered structure composite for high-efficient solar evaporation based on photothermal-enhanced arginine-doped polydopamine (APDA) and raw wood, which are biodegradable and sustainable. Note that the APDA coating layer exhibited improved optical absorption and photothermal conversion ability compared with conventional polydopamine (PDA) coating on account of the construction of donor-acceptor pairs within the APDA microstructure system. Density functional theory (DTF) calculation further confirmed that the energy bandgap of APDA could be narrowed though donor-acceptor microstructures and then enhanced the absorption spectrum. The resulting APDA-wood composite performed a solar vapor generation efficiency of ~77% on the condition of 1 sun illumination. The water evaporation process was quite stable over 100 cycles and the metal ions in seawater were almost eliminated after desalination. This amino acid-initiated cost-effective and facile coating method provided new opportunities to fabricate photothermal-enhanced coating materials for solar evaporation applications.
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•APDA is prepared with improved light absorption and total photothermal effect.•Donor-acceptor microstructures within the APDA system could decrease the bandgap.•APDA-wood composite is fabricated for efficient solar steam generation.
Wearable pressure sensors are in great demand with the rapid development of intelligent electronic devices. However, it is still a huge challenge to obtain high-performance pressure sensors with high ...sensitivity, wide response range, and low detection limit simultaneously. Here, a polyimide (PI)/carbon nanotube (CNT) composite aerogel with the merits of superelastic, high porosity, robust, and high-temperature resistance was successfully prepared through the freeze drying plus thermal imidization process. Benefiting from the strong chemical interactions between PI and CNT and stable electrical property, the composite aerogel exhibits versatile and superior brilliant sensing performance, which includes wide sensing range (80% strain, 61 kPa), ultrahigh sensitivity (11.28 kPa–1), ultralow detection limit (0.1% strain, <10 Pa), fast response time (50 ms) and recovery time (70 ms), remarkable long-term stability (1000 cycles), and exceptional detection ability toward different deformations (compression, distortion, and bending). Furthermore, the composite aerogel also shows stable sensing performance after annealing under different high temperatures and good thermal insulation property, making it workable in various harsh environments. As a result, the composite aerogel is suitable for the full-range human motion detection (including airflow, pulse, vocal cord vibration, and human movement) and precise detection of the pressure distribution when it is assembled into E-skin, demonstrating its great potential to serve as a high-performance wearable pressure sensor.
Surface suppression is one of critical issues for semiconductors in photoelectrochemical (PEC) water splitting. Deposition of oxygen evolution cocatalysts on photoanodes can improve the oxygen ...evolution rate, but still it has some limits in some cases. In this work, we propose a new and simple precipitation approach to transform the surface of hematite into iron phosphate (Fe–Pi). Further, Ar-plasma treatment on Fe–Pi/Fe2O3 introduces oxygen vacancies on the phosphorous and photoanode. A surface phosphate treatment accelerates the transfer of holes from the bulk to the surface. Besides, creating oxygen vacancy defects on Fe–Pi/Fe2O3 can significantly increase the reactivity of active sites, leading to the remarkable enhancement in oxygen evolution reaction activity and PEC performance. The resulting photoanode has a current density of 2.71 mA cm–2 at 1.23 VRHE and 3.5 mA cm–2 at 1.50 VRHE under simulated solar light condition. The reduced surface recombination by Fe–Pi layer and Ar-plasma treatment is confirmed by electrochemical analysis. These findings give a great potential of the use of a combination strategy for cocatalyst deposition and optimizing the performance of hematite.
Hybrid fillers of different geometries are increasingly utilized for the development of functional polymer composites. We herein report the role of HDPE-g-MAH as a compatibilizer for ternary ...composites consisting of HDPE, multi-walled carbon nanotubes and hexagonal boron nitride (BN). Through melt blending, HDPE-g-MAH can reduce the agglomeration of fillers and facilitate the formation of network structure. Due to the synergistic effect, ternary composites have demonstrated significantly higher thermal conductivity than those binary composites, and their maximum increase relative to the matrix is 262%. The mechanical performance and thermal conductivity are explained from perspectives of the morphology and crystallinity of the composites. The rheological properties of both binary and ternary composites have close relationship with their thermal conductivity. Although a high fraction of BN nanosheets can greatly reduce the electrical conductivity of ternary composites, they posed little effect on the electromagnetic interference shielding performance, owing to their electrical insulating nature. This research can provide new clues for the development of functional materials.
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Highlights
Interface engineering of heterogeneous CoS/CoO nanocrystals and N-doped graphene composite facilitates high-performance oxygen reduction reaction and oxygen evolution reaction.
Density ...functional theory calculations and experimental results confirm the enhanced electrocatalytic performances via the proposed interface engineering.
The bifunctional oxygen electrocatalyst exhibits excellent performances in rechargeable Zn–air batteries.
Low cost and green fabrication of high-performance electrocatalysts with earth-abundant resources for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are crucial for the large-scale application of rechargeable Zn–air batteries (ZABs). In this work, our density functional theory calculations on the electrocatalyst suggest that the rational construction of interfacial structure can induce local charge redistribution, improve the electronic conductivity and enhance the catalyst stability. In order to realize such a structure, we spatially immobilize heterogeneous CoS/CoO nanocrystals onto N-doped graphene to synthesize a bifunctional electrocatalyst (CoS/CoO@NGNs). The optimization of the composition, interfacial structure and conductivity of the electrocatalyst is conducted to achieve bifunctional catalytic activity and deliver outstanding efficiency and stability for both ORR and OER. The aqueous ZAB with the as-prepared CoS/CoO@NGNs cathode displays a high maximum power density of 137.8 mW cm
−2
, a specific capacity of 723.9 mAh g
−1
and excellent cycling stability (continuous operating for 100 h) with a high round-trip efficiency. In addition, the assembled quasi-solid-state ZAB also exhibits outstanding mechanical flexibility besides high battery performances, showing great potential for applications in flexible and wearable electronic devices.
Increasing long‐term photostability of BiVO4 photoelectrode is an important issue for solar water splitting. The NiOOH oxygen evolution catalyst (OEC) has fast water oxidation kinetics compared to ...the FeOOH OEC. However, it generally shows a lower photoresponse and poor stability because of the more substantial interface recombination at the NiOOH/BiVO4 junction. Herein, we utilize a plasma etching approach to reduce both interface/surface recombination at NiOOH/BiVO4 and NiOOH/electrolyte junctions. Further, adding Fe2+ into the borate buffer electrolyte alleviates the active but unstable character of etched‐NiOOH/BiVO4, leading to an outstanding oxygen evolution over 200 h. The improved charge transfer and photostability can be attributed to the active defects and a mixture of NiOOH/NiO/Ni in OEC induced by plasma etching. Metallic Ni acts as the ion source for the in situ generation of the NiFe OEC over long‐term durability.
Flex your PECs: A facile plasma etching approach was utilized to reduce both interface/surface recombination at NiOOH/BiVO4 and NiOOH/electrolyte junctions for photoelectrochemical (PEC) catalysis of water splitting. Addition of Fe2+ into the borate buffer electrolyte alleviated the active but unstable character of etched‐NiOOH/BiVO4, leading to an outstanding photostability over 200 h.
Highlights
General principles for designing atomically dispersed metal-nitrogen-carbon (M–N-C) are briefly reviewed.
Strategies to enhance the bifunctional catalytic performance of atomically ...dispersed M–N-C are summarized.
Challenges and perspectives of M–N-C bifunctional oxygen catalysts for Rechargeable zinc-air batteries are discussed.
Rechargeable zinc-air batteries (ZABs) are currently receiving extensive attention because of their extremely high theoretical specific energy density, low manufacturing costs, and environmental friendliness. Exploring bifunctional catalysts with high activity and stability to overcome sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction is critical for the development of rechargeable ZABs. Atomically dispersed metal-nitrogen-carbon (M-N-C) catalysts possessing prominent advantages of high metal atom utilization and electrocatalytic activity are promising candidates to promote oxygen electrocatalysis. In this work, general principles for designing atomically dispersed M-N-C are reviewed. Then, strategies aiming at enhancing the bifunctional catalytic activity and stability are presented. Finally, the challenges and perspectives of M-N-C bifunctional oxygen catalysts for ZABs are outlined. It is expected that this review will provide insights into the targeted optimization of atomically dispersed M-N-C catalysts in rechargeable ZABs.
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