Abstract
Resistance change under mechanical stimuli arouses mass operational heat, damaging the performance, lifetime, and reliability of stretchable electronic devices, therefore rapid thermal heat ...dissipating is necessary. Here we report a stretchable strain sensor with outstanding thermal management. Besides a high stretchability and sensitivity testified by human motion monitoring, as well as long-term durability, an enhanced thermal conductivity from the casted thermoplastic polyurethane-boron nitride nanosheets layer helps rapid heat transmission to the environments, while the porous electrospun fibrous thermoplastic polyurethane membrane leads to thermal insulation. A 32% drop of the real time saturated temperature is achieved. For the first time we in-situ investigated the dynamic operational temperature fluctuation of stretchable electronics under repeating stretching-releasing processes. Finally, cytotoxicity test confirms that the nanofillers are tightly restricted in the nanocomposites, making it harmless to human health. All the results prove it an excellent candidate for the next-generation of wearable devices.
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•Recent advances in increasing hydrolysis are introduced.•Strategies for enhancing enzyme activity relevant with VFA generation are reviewed.•Acceleration of direct interspecies ...electron transfer facilitates methanogenesis.•Improving methane production through special pathway is beneficial to anaerobic digestion.•Techno-economic assessment of approaches in the lab-scale is presented.
With the increase of energy consumption and wastes generation due to human activities, anaerobic digestion (AD), a technology which turns wastes into bio-energy, is receiving more and more attention in the world. It is well known that there are at least three stages involved in anaerobic digestion, i.e., hydrolysis, acidification, and methanogenesis. Until now, however, the advances in enhancing acidification and methanogenesis have not been reviewed. This review provides a comprehensive overview of the methods reported to enhance each step involved in anaerobic digestion. More important, enzymes are the key to anaerobic digestion, and the strategies for improving enzyme activity are summarized. As electron transfer has been reported to play an important role in anaerobic digestion, the research progress of the approaches for the acceleration of direct interspecies electron transfer in methane production is also introduced. In addition, the recent advances in increasing the reduction of carbon dioxide to methane, which has been widely observed in methanogenesis step, are reviewed. Furthermore, the techno-economic assessment of anaerobic digestion is made, and the key points for future studies are proposed.
•A novel refrigerant-based battery thermal management system is proposed.•Temperature distributions and boiling characteristics are predicted.•The maximum temperature is inversely correlated with ...refrigerant inlet velocity.•Temperature uniformity is predominantly affected by nucleate boiling heat transfer.
In this paper, a novel battery thermal management system (BTMS) using the dielectric, non-flammable HFE-7000 refrigerant is proposed for electric vehicles (EVs). Its thermal performance is studied both numerically and experimentally. The refrigerant flows and boils on the battery wall surfaces, which lowers the thermal contact resistance as well as enhances the heat transfer process. Therefore, the thermal performance of the battery module is improved. The results indicate that forced convection heat transfer of the liquid refrigerant is dominating in the control of the temperature rise in the battery module. The maximum battery temperature drops to 35.10°C at 0.3ms-1 inlet velocity and a 5C discharge rate. In contrast, the temperature uniformity between individual battery cells primarily depends on the nucleate boiling heat absorption and local perturbation of the two-phase turbulent flow. A temperature difference of no more than 3.71°C can be observed at 5C discharge rate and 0.1ms- 1. In addition, good agreement was found between the numerical results and experimental data.
The Poisson's ratio is a fundamental mechanical property that relates the resulting lateral strain to applied axial strain. Although this value can theoretically be negative, it is positive for ...nearly all materials, though negative values have been observed in so-called auxetic structures. However, nearly all auxetic materials are bulk materials whose microstructure has been specifically engineered to generate a negative Poisson's ratio. Here we report using first-principles calculations the existence of a negative Poisson's ratio in a single-layer, two-dimensional material, black phosphorus. In contrast to engineered bulk auxetics, this behaviour is intrinsic for single-layer black phosphorus, and originates from its puckered structure, where the pucker can be regarded as a re-entrant structure that is comprised of two coupled orthogonal hinges. As a result of this atomic structure, a negative Poisson's ratio is observed in the out-of-plane direction under uniaxial deformation in the direction parallel to the pucker.
A new class of 2D transition metal carbides, carbonitrides and nitrides, termed MXenes, has emerged as a new candidate for many applications in electronics, optoelectronics, and energy storage. Since ...their first discovery in 2011, MXenes have gathered increasingly more interest owing to their unique physical, chemical, and mechanical properties that can be tuned by different surface terminations and transition metals. In particular, the intriguing optical and electrical properties, including transparency, saturable absorption, and high conductivity, grant MXenes various roles in photodetectors, such as transparent electrodes, Schottky contacts, photoabsorbers, and plasmonic materials. Given the solution‐processability, MXenes also hold great potential for large‐scale synthesis, and thus are favored for a number of electronic and photonic device applications. In this review, recent advances in photodetectors based on 2D MXenes are summarized. Despite the fact that such applications have only recently been explored compared with other 2D materials, MXenes have shown promise in low‐cost and high‐performance photodetection.
Since their first discovery in 2011, MXenes have gained ever increasing interest. Despite their intriguing optical and electrical properties for optoelectronics, 2D MXenes have been thus far marginally explored for photodetectors. Nonetheless, the progress over the past few years cannot be ignored. In this review, the recent development of MXene photodetectors is summarized, including simple photoconductors, self‐driven photodetectors, and plasmon‐enhanced photodetectors.
Graphene and MoS2 are two well-known quasi two-dimensional materials. This review presents a comparative survey of the complementary lattice dynamical and mechanical properties of graphene and MoSs, ...which facilitates the study of graphene/MoS2 heterostructures. These hybrid heterostructures are expected to mitigate the negative properties of each individual constituent and have attracted intense academic and industrial research interest.
Black phosphorus is a two-dimensional material of great interest, in part because of its high carrier mobility and thickness dependent direct bandgap. However, its instability under ambient ...conditions limits material deposition options for device fabrication. Here we show a black phosphorus ink that can be reliably inkjet printed, enabling scalable development of optoelectronic and photonic devices. Our binder-free ink suppresses coffee ring formation through induced recirculating Marangoni flow, and supports excellent consistency (< 2% variation) and spatial uniformity (< 3.4% variation), without substrate pre-treatment. Due to rapid ink drying (< 10 s at < 60 °C), printing causes minimal oxidation. Following encapsulation, the printed black phosphorus is stable against long-term (> 30 days) oxidation. We demonstrate printed black phosphorus as a passive switch for ultrafast lasers, stable against intense irradiation, and as a visible to near-infrared photodetector with high responsivities. Our work highlights the promise of this material as a functional ink platform for printed devices.Atomically thin black phosphorus shows promise for optoelectronics and photonics, yet its instability under environmental conditions and the lack of well-established large-area synthesis protocols hinder its applications. Here, the authors demonstrate a stable black phosphorus ink suitable for printed ultrafast lasers and photodetectors.
Abstract
Defects can induce drastic changes of the electronic properties of two-dimensional transition metal dichalcogenides and influence their applications. It is still a great challenge to ...characterize small defects and correlate their structures with properties. Here, we show that tip-enhanced Raman spectroscopy (TERS) can obtain distinctly different Raman features of edge defects in atomically thin MoS
2
, which allows us to probe their unique electronic properties and identify defect types (e.g., armchair and zigzag edges) in ambient. We observed an edge-induced Raman peak (396 cm
−1
) activated by the double resonance Raman scattering (DRRS) process and revealed electron–phonon interaction in edges. We further visualize the edge-induced band bending region by using this DRRS peak and electronic transition region using the electron density-sensitive Raman peak at 406 cm
−1
. The power of TERS demonstrated in MoS
2
can also be extended to other 2D materials, which may guide the defect engineering for desired properties.
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