It is demonstrated that homo-doping is a simple and effective strategy to improve near-infrared (NIR) photoresponsive performance of a WO3−x-WSe2/SiO2/n-Si heterojunction. Our systematic studies ...showed that an air thermal annealing treatment can enrich the p-WO3−x dopants of WSe2, which was essential to greatly enhance the NIR photoresponsive performance of the WO3−x-WSe2/SiO2/n-Si heterojunction. Moreover, this heterojunction exhibited excellent selectivity and good stability to the incident light of 900 nm with high photoresponsivity of ∼137.7 A W−1, superior detectivity (D*) of ∼2.27 × 1014 Jones (1 Jones = 1 cm Hz1/2 W−1), and prominent sensitivity (S) of ∼1.19 × 108 cm2 W−1. When compared with the WSe2/SiO2/n-Si heterojunction, D* was increased by a factor of 7 and S was enhanced by a factor of 35. Comprehensive performance analyses indicate that the device fabricated in this work is not only significantly better than most of the reported Si based devices, but also can be comparable with 0D and 2D based nanostructure heterojunction devices. Systematic NIR photoresponsive studies demonstrate that the enhanced photoresponsive performance can be mainly attributed to the down-shift of the Fermi level of p–p homo-doped WO3−x-WSe2, which generates the larger interface barrier height between WO3−x-WSe2 and n-Si and the weaker dark current of the p–p homo-doped WO3−x-WSe2/SiO2/n-Si heterojunction. Our studies demonstrate that the homo-doping approach may be extended to fundamentally modify other semiconductor based photodetectors.
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•WO3-W18O49 heterostructures with loose nanowire bundle-like morphology are synthesized via a novel one-step approach.•The WO3-W18O49 heterostructures are firstly applied in NH3 ...detection with great gas sensing performance.•The enhanced gas sensing performance of WO3-W18O49 heterostructures is explained by applying n-n heterojunction theory.
Heterojunctions are very promising structures due to their hybrid properties, which are usually obtained via a multistep growth process. However, in this paper, WO3-W18O49 heterostructures are synthesized via a novel one-step approach by using isopropanol as reaction media and are applied in NH3 gas detection for the first time. The obtained WO3-W18O49 heterostructures with loose nanowire bundle-like morphology show a response value of 23.3 toward 500 ppm NH3 at 250 °C, which is 5.63 times higher than that of pristine W18O49. In addition, the WO3-W18O49 sensor also exhibits great dynamic response/recovery characteristics (13 s/49 s @ 500 ppm NH3), superb selectivity and low detection limit of 460 ppb. The substantial improvement in the response of WO3-W18O49 heterostructures toward NH3 can be explained by the formation of n-WO3/n-W18O49 heterojunctions that facilitate the generation of a more extended depletion layer as well as the enhancement of specific surface area and pore volume. Our research results open an easy pathway for facile one-step preparation of heterojunctions with high response and low cost, which can be used for the development of other high-performance gas sensors.
Aqueous zinc‐ion batteries are regarded as ideal candidates for stationary energy‐storage systems due to their low cost and high safety. However, zinc can readily grow into dendrites, leading to ...limited cycling performance and quick failure of the batteries. Herein, a novel strategy is proposed to mitigate this dendrite problem, in which a selectively polarized ferroelectric polymer material (poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE))) is employed as a surface protective layer on zinc anodes. Such a polarized ferroelectric polymer layer can enable a locally concentrated zinc‐ion distribution along the coated surface and thus enable the horizontal growth of zinc plates. As a result, symmetrical zinc batteries using such anodes exhibit long cycling lifespan at 0.2 mA cm−2, 0.2 mAh cm−2 for 2000 h, and a high rate performance up to 15 mA cm−2. Also, the full cell (including a Zn–MnO2 battery and a zinc‐ion capacitor) based on this anode is demonstrated. This work provides a novel strategy to protect the zinc anode and even other metal anodes exploiting polymer ferroelectricity.
A thin ferroelectric polymer (poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE))) film is constructed on a zinc‐metal anode as a surface protective layer. After selective polarization, such a protective layer could enable a locally concentrated zinc‐ion distribution along the coated surface, and thus induce zinc to grow into horizontally aligned plates. Highly stable zinc batteries are achieved via such modified zinc anodes.
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•A hierarchical structured mesh decorated with UiO-66-NH2/GO was prepared.•The hierarchical structured mesh possessed super-hydrophilicity and underwater super-oleophobicity.•The ...hierarchical structured mesh exhibited outstanding antifouling performance.•The hierarchical structured mesh possessed super-high separation performance and recycling capacity.
A hierarchical structured steel mesh decorated with metal organic framework (UiO-66-NH2) nanoparticles/graphene oxide (GO) nanosheets was successfully prepared via a simple self-assemble method. Because water molecules tend to build hydrogen bonds with the amine, carboxyl and hydroxyl functional groups of UiO-66-NH2/GO hierarchical structure, the hierarchical structure can easily capture water and tightly lock the water to build a stable water layer on the steel mesh surface and block oil in contact with the steel mesh. Therefore, the obtained hierarchical structured steel mesh exhibits super-hydrophilicity, underwater super-oleophobicity, excellent oil resistance and outstanding oil/water separation performance with a superior high permeating flux (54,500 L m−2 h−1) and rejection (>99.9%) under gravity force, indicating the mesh possesses great potential for treating oily wastewater.
Energy harvesting modules play an increasingly important role in the development of autonomous self‐powered microelectronic devices. MXenes (i.e., 2D transition metal carbide/nitride) have recently ...emerged as promising candidates for energy applications due to their excellent electronic conductivity, large specific surface area, and tunable properties. Herein, a perspective on using MXenes to harvest energy from various sources in the environment is presented. First, the characteristics of MXenes that facilitate energy capturing are systematically introduced and the preparation strategies of MXenes and their derived nanostructures tailored toward such applications are summarized. Subsequently, the harvesting mechanism of different energy sources (e.g., solar energy, thermoelectric energy, triboelectric energy, piezoelectric energy, salinity‐gradient energy, electrokinetic energy, ultrasound energy, and humidity energy) are discussed. Then, the recent progress of MXene‐based nanostructures in energy harvesting, as well as their applications, is introduced. Finally, opinions on the existing challenges and future directions of MXene‐based nanostructure for energy harvesting are presented.
The progress in employing MXenes in energy harvesting applications is summarized. Different energy sources, including solar, ultrasound, electrokinetic, salinity‐gradient, piezoelectric, triboelectric, thermoelectric, and humidity energy, are discussed separately. The future challenges and promising directions of MXene research for energy harvesting are presented.
The composite nanofibrous membrane (CNFM) was fabricated via decorating MOFs on electrospun polyacrylonitrile membrane (PANM), which has high-efficiency separation performance for oil-water emulsions ...under gravity.
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•A polyacrylonitrile nanofibrous membrane decorated with MOFs is prepared.•The CNFM possesses superhydrophilicity and underwater superoleophobicity.•The CNFM exhibits outstanding antifouling performance.•The CNFM possesses excellent separation performance and recycling capacity.
A nanofibrous polyacrylonitrile membrane decorated with metal-organic frameworks (MOFs) of UiO-66-NH2 is prepared via a simple and flexible self-assemble method. It is found that the membrane shows high-efficiency separation performance of oil-water emulsions, due to the hydrophilic carboxyl and amino groups of UiO-66-NH2 and the gaps between neighboring UiO-66-NH2. Remarkably, solely driven by gravity (∼0.01 bar), the obtained membrane can effectively separate oil-water emulsions with an excellent separation efficiency (>99%, TOC < 10 mg/L) and a high flux (2107 Lm−2 h−1). It is demonstrated that the hydrophilic carboxyl and amino groups of UiO-66-NH2 enhance the superhydrophilicity and underwater superoleophobicity of the membrane so as to greatly improve the antifouling properties of the membrane. Besides, because the size of gaps between neighboring UiO-66-NH2 is mostly much smaller than that of oil drops and the UiO-66-NH2 are underwater oleophobic, the oil drops hardly enter the gaps between neighboring UiO-66-NH2 so that the gaps provide much more water flow tunnels, which obviously enhance the flux of the membrane. In this study, we present a new avenue of building MOFs loaded nanofibrous membrane with excellent oil-water separation performance.
The negatively charged C3N nanosheet exhibits excellent switchable storage and release capacity for selective CO2 capture.
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•The negatively charged C3N nanomaterial shows high CO2 ...adsorption capacity.•CO2 regeneration is simply modulated by injecting and removing extra negative charges.•The selective CO2 capture from mixtures is easily realized by tuning charge density.
Increasing concerns about the atmospheric CO2 concentration and its impact on the environment promote developing new materials and technologies for efficient CO2 capture and conversion. Here, for the first time we investigate the CO2 adsorption on C3N nanosheet with different charge states by means of density functional theory calculations. It is found that injecting extra negative electrons instead of positive electrons can extremely improve CO2 adsorption capacity of C3N nanomaterial. The adsorption strength of CO2 molecules on this 3 e− negatively charged nanomaterial is 20 times of that on neutral surface while there is little difference between these on positively charged surface and the neutral surface. Interestingly, CO2 molecules can spontaneously adsorb and desorb from C3N sorbent with appropriate charge density range by injecting and removing extra negative charges. Importantly, this negatively charged C3N exhibits highly selective adsorption for CO2/C2H2, CO2/CH4, CO2/H2, C2H2/CH4 and C2H2/H2 mixtures through tuning charge density. Our theoretical results could provide guidance for designing high-capacity and high-selectivity CO2 capture materials.
•A SSM/PDA/GO mesh for oil/water mixture separation has been successfully prepared.•The synergistic effect of PDA and GO greatly enhances the superhydrophilicity.•The multilevel structure of ...SSM/PDA/GO enhances the anti-fouling property.•The SSM/PDA/GO exhibits excellent wetting behavior and separation performance.
An environmental-friendly stainless steel mesh (SSM) decorated with polydopamine (PDA) and graphene oxide (GO) for oil/water mixture separation was successfully fabricated via a facile dipping coating method. PDA particles were firstly modified on the mesh surface by the self-polymerization of dopamine. Then, GO was firmly anchored onto the surface of PDA particles through the covalent bonds or electrostatic interaction between GO and PDA. Finally, a SSM/PDA/GO multilevel structure was prepared, which shows superior hydrophilicity and excellent anti-fouling properties due to the hydrophilic functional groups and a thicker water layer confined inside SSM/PDA/GO multilevel structure. Therefore, the as-prepared SSM/PDA/GO mesh with a large oil intrusion pressure (>3 kPa) can separate oil/water mixture with ultra-high flux (∼15,000 L m−2 h−1), preferable separation efficiency (>99.95%) and outstanding recyclability. Furthermore, the SSM/PDA/GO possesses superior stability under harsh environmental conditions, which indicates that the mesh is a promising candidate for practical oil spill cleanup in harsh conditions, especially in high salty marine environment.
Wafer‐scale growth has become a critical bottleneck for scaling up applications of van der Waal (vdW) layered 2D materials in high‐end electronics and optoelectronics. Most vdW 2D materials are ...initially obtained through top‐down synthesis methods, such as exfoliation, which can only prepare small flakes on a micrometer scale. Bottom‐up growth can enable 2D flake growth over a large area. However, seamless merging of these flakes to form large‐area continuous films with well‐controlled layer thickness and lattice orientation is still a significant challenge. This review briefly introduces several vdW layered 2D materials covering their lattice structures, representative physical properties, and potential roles in large‐scale applications. Then, several methods used to grow vdW layered 2D materials at the wafer scale are reviewed in depth. In particular, three strategies are summarized that enable 2D film growth with a single‐crystalline structure over the whole wafer: growth of an isolated domain, growth of unidirectional domains, and conversion of oriented precursors. After that, the progress in using wafer‐scale 2D materials in integrated devices and advanced epitaxy is reviewed. Finally, future directions in the growth and scaling of vdW layered 2D materials are discussed.
This review introduces various 2D van der Waals layered materials and summarizes their wafer‐scale growth processes, including strategies for mono‐orientated film growth. Applications of these materials in integrated devices and new epitaxial technologies are discussed, as well as the required future research directions in this very important field.
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