Synaptic transistors stimulated by light waves or photons may offer advantages to the devices, such as wide bandwidth, ultrafast signal transmission, and robustness. However, previously reported ...light-stimulated synaptic devices generally require special photoelectric properties from the semiconductors and sophisticated device’s architectures. In this work, a simple and effective strategy for fabricating light-stimulated synaptic transistors is provided by utilizing interface charge trapping effect of organic field-effect transistors (OFETs). Significantly, our devices exhibited highly synapselike behaviors, such as excitatory postsynaptic current (EPSC) and pair-pulse facilitation (PPF), and presented memory and learning ability. The EPSC decay, PPF curves, and forgetting behavior can be well expressed by mathematical equations for synaptic devices, indicating that interfacial charge trapping effect of OFETs can be utilized as a reliable strategy to realize organic light-stimulated synapses. Therefore, this work provides a simple and effective strategy for fabricating light-stimulated synaptic transistors with both memory and learning ability, which enlightens a new direction for developing neuromorphic devices.
A highly hydrophilic PVDF membrane was fabricated through chemically binding TiO2 nanoparticles and a poly(vinyl alcohol) (PVA) layer onto a membrane surface simultaneously. The chemical composition ...of the modified membrane surface was determined by X-ray photoelectron spectroscopy, and the binding performance of TiO2 nanoparticles and the PVA layer was investigated by a rinsing test. The results indicated that the TiO2 nanoparticles were uniformly and strongly tailored onto the membrane surface, while the PVA layer was firmly attached onto the surface of TiO2 nanoparticles and the membrane by adsorption-cross-linking. The possible mechanisms during the modification process and filtration performance, i.e., water permeability and bovine serum albumin (BSA) rejection, were investigated as well. Furthermore, antifouling property was discussed through multicycles of BSA solution filtration tests, where the flux recovery ratio was significantly increased from 20.0% for pristine PVDF membrane to 80.5% for PVDF/TiO2/PVA-modified membrane. This remarkable promotion is mainly ascribed to the improvement of surface hydrophilicity, where the water contact angle of the membrane surface was decreased from 84° for pristine membrane to 24° for PVDF/TiO2/PVA membrane. This study presents a novel and varied strategy for immobilization of nanoparticles and PVA layer on substrate surface, which could be easily adapted for a variety of materials for surface modification.
Abstract Theranostics, the integration of diagnostics and therapies, has become a new concept in the battles with various major diseases such as cancer. Here, we report a multifunctional ...nanoplatform, which is developed by covalently grafting core–shell structured upconversion nanoparticles (UCNPs) with nanographene oxide (NGO) via bifunctional polyethylene glycol (PEG), and then loading phthalocyanine (ZnPc) on the surface of NGO. The obtained UCNPs-NGO/ZnPc nanocomposites are not only be used as upconversion luminescence (UCL) imaging probes of cells and whole-body animals with high contrast for diagnosis, but also can generate cytotoxic singlet oxygen under light excitation for photodynamic therapy (PDT), as well as rapidly and efficiently convert the 808 nm laser energy into thermal energy for photothermal therapy (PTT). A remarkably improved and synergistic therapeutic effect compared to PTT or PDT alone is obtained, providing high therapeutic efficiency for cancer treatment. Therefore, benefiting from the unique multifunctional hybrid nanostructure, UCNPs-NGO/ZnPc nanocomposites developed herein are promising as an integrated theranostic probe for potential UCL image-guided combinatorial PDT/PTT of cancer.
The thin‐film structures of chemical sensors based on conventional organic field‐effect transistors (OFETs) can limit the sensitivity of the devices toward chemical vapors, because charge carriers in ...OFETs are usually concentrated within a few molecular layers at the bottom of the organic semiconductor (OSC) film near the dielectric/semiconductor interface. Chemical vapor molecules have to diffuse through the OSC films before they can interact with charge carriers in the OFET conduction channel. It has been demonstrated that OFET ammonia sensors with porous OSC films can be fabricated by a simple vacuum freeze‐drying template method. The resulted devices can have ammonia sensitivity not only much higher than the pristine OFETs with thin‐film structure but also better than any previously reported OFET sensors, to the best of our knowledge. The porous OFETs show a relative sensitivity as high as 340% ppm−1 upon exposure to 10 parts per billion (ppb) NH3. In addition, the devices also exhibit decent selectivity and stability. This general and simple strategy can be applied to a wide range of OFET chemical sensors to improve the device sensitivity.
Organic field‐effect transistor (OFET)‐based chemical sensors with porous film structure are fabricated by a versatile and low‐cost template method. OFET chemical sensors with the porous structure exhibit much higher sensitivity than that of the pristine one. Porous OFETs exhibit obvious and reproducible response to 10 ppb NH3, with a relative sensitivity up to 340% ppm−1. The devices also show decent stability and sensing selectivity.
Abstract
Nowadays, energy-saving building materials are important for reducing indoor energy consumption by enabling better thermal insulation, promoting effective sunlight harvesting and offering ...comfortable indoor lighting. Here, we demonstrate a novel scalable aesthetic transparent wood (called aesthetic wood hereafter) with combined aesthetic features (e.g. intact wood patterns), excellent optical properties (an average transmittance of ~ 80% and a haze of ~ 93%), good UV-blocking ability, and low thermal conductivity (0.24 W m
−1
K
−1
) based on a process of spatially selective delignification and epoxy infiltration. Moreover, the rapid fabrication process and mechanical robustness (a high longitudinal tensile strength of 91.95 MPa and toughness of 2.73 MJ m
−3
) of the aesthetic wood facilitate good scale-up capability (320 mm × 170 mm × 0.6 mm) while saving large amounts of time and energy. The aesthetic wood holds great potential in energy-efficient building applications, such as glass ceilings, rooftops, transparent decorations, and indoor panels.
Zn-based batteries have attracted extensive attention due to their high theoretical energy density, safety, abundant resources, environmental friendliness, and low cost. They are a new energy storage ...and conversion technology with significant development potential and have been widely used in renewable energy and portable electronic devices. Considerable attempts have been devoted to improving the performance of Zn-based batteries. Specifically, battery cycle life and energy efficiency can be improved by electrolyte modification and the construction of highly efficient rechargeable Zn anodes. This review compiles the progress of the research related to Zn anodes and electrolytes, especially in the last five years. This review will introduce fundamental concepts, summarize recent development, and inspire further systematic research for high-performance Zn-based batteries in the future.
Biodegradability, low-voltage operation, and flexibility are important trends for the future organic electronics. High-capacitance dielectrics are essential for low-voltage organic field-effect ...transistors. Here we report the application of environmental-friendly cellulose nanopapers as high-capacitance dielectrics with intrinsic ionic conductivity. Different with the previously reported liquid/electrolyte-gated dielectrics, cellulose nanopapers can be applied as all-solid dielectrics without any liquid or gel. Organic field-effect transistors fabricated with cellulose nanopaper dielectrics exhibit good transistor performances under operation voltage below 2 V, and no discernible drain current change is observed when the device is under bending with radius down to 1 mm. Interesting properties of the cellulose nanopapers, such as ionic conductivity, ultra-smooth surface (~0.59 nm), high transparency (above 80%) and flexibility make them excellent candidates as high-capacitance dielectrics for flexible, transparent and low-voltage electronics.
Highly ordered Ni-MCM-41 catalysts were prepared by a direct hydrothermal synthesis, and the catalytic properties were studied for the reforming of methane with carbon dioxide. The results indicated ...that Ni-MCM-41 catalyst by direct incorporation method shows superior catalytic stability compared to impregnated samples. The improved catalytic performance closely associated with the anchoring effect.
A series of nickel incorporated MCM-41 mesoporous molecular sieves (Ni-MCM-41) were prepared by direct hydrothermal synthesis. Nickel nitrate was used as the Ni precursor. The catalytic properties of the Ni-MCM-41 were studied for the reforming of methane with carbon dioxide. The catalysts were carefully characterized by X-ray diffraction (XRD), N
2 physisorption, H
2 temperature-programmed reduction (TPR), H
2 chemisorption, thermogravimetry, and Raman spectra. The results indicated that the presence of a suitable amount of nickel in Ni-MCM-41 was beneficial for maintaining high catalytic activity and long-term stability. The improved catalytic performance was suggested to closely associate with both the amount of active centers on the pore wall surface and the stabilized dispersion of these active sites by the silica matrix and/or the surrounding unreduced nickel ions. This anchoring effect facilitated the formation of the active Ni nano-clusters with high dispersion under reaction conditions. Hence the reforming reaction is favored and the carbon formation is suppressed. Two types of carbon species: active carbon and graphite were produced over the spent catalysts. The Ni-MCM-41 catalysts provided good catalytic activity, high stability and reasonable CO/H
2 ratios in the product. Thus, the Ni-MCM-41 catalyst prepared by the direct hydrothermal synthesis promised a novel and stable catalyst candidate for CO
2 reforming of CH
4.
Water splitting requires nonprecious materials that can catalyze efficiently both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Here, we report the synthesis of ...mackinawite FeS nanosheets grown on iron foam, which can serve as an efficient pre-electrocatalyst for both HER and OER in alkaline media. During electrochemical HER testing, core@shell iron@iron oxysulfide nanoparticles as the catalytically active phase are generated in situ on FeS nanosheets. During electrochemical OER testing, FeS nanosheets totally transform into porous amorphous FeOx film that can mediate the OER efficiently. When assembled as the cathode and the anode in a single electrolyzer, the resulting Fe-based catalysts can give a good overall water-splitting output that outperforms the one obtained from a noble-metal-based Pt/C-IrO2-coupled electrolyzer. These results provide new insights on the active sites of Fe-based catalysts as well as an impetus for further research on low-cost, iron-containing water-splitting electrocatalysts.
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•Mackinawite FeS nanosheet arrays grown on iron foam are prepared•The core@shell iron@iron oxysulfide nanoparticles are active for HER•A porous, amorphous FeOx thin film is an efficient catalyst for OER•A high-performance electrolyzer based on Fe-based electrodes is constructed
Electrochemical water splitting for hydrogen production is often considered to be integrated into existing systems that generate renewable power because hydrogen can work as a versatile energy carrier and can overcome the intermittency of typical renewable energy resources, such as wind and solar energy. The two half reactions involved in water splitting—the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER)—traditionally have to be electrocatalyzed by noble-metal-based materials (e.g., Pt/C for HER and IrO2 for OER). Here, mackinawite FeS nanosheets grown on iron foam are identified as a low-cost pre-electrocatalyst for generating highly active, Fe-based electrodes for both HER and OER. When assembled as the cathode and the anode in a single electrolyzer, the resulting Fe-based electrodes can give an overall water-splitting output that outperforms the one obtained from a noble-metal-based Pt/C-IrO2-coupled electrolyzer.
Mackinawite FeS nanosheets grown on iron foam have been synthesized and identified as a low-cost pre-electrocatalyst for generating highly active electrocatalysts (i.e., Fe-H2cat and Fe-O2cat) for both HER and OER. The water-splitting output of the electrolyzer based on Fe-H2cat and Fe-O2cat is comparable with that of an electrolyzer assembled by a Pt/C-IrO2 catalytic couple at small current densities but exhibits better water-splitting output at large current densities.
Spontaneous combustion of coal is one of the major hazards threatening production safety during longwall mining. Mining-induced voids, which provide passages for air leakage, are the key factor ...triggering spontaneous combustion of coal in longwall goafs. In this study, a comprehensive method, which combined pressure balance, grouting injection, and filling fissures, was proposed to prevent spontaneous combustion of coal in longwall goafs with complex air leakage. Field engineering practice was carried out in Sitai Coal Mine in China. The results demonstrated that with the application of the proposed method, in the working face, the concentration of CO was decreased from 31ppm to 0 and the air leakage quantity was decreased from 261 to below 80 m3min-1. The gas samples analysis from the gob areas also indicated that concentrations of O2 and CO were successively decreased, indicating that the risk of spontaneous combustion of coal in goafs was eliminated. The above mentioned analysis indicates that, the method proposed in this study is useful and efficient. Successful application of this technology could provide reference for the treatment of other coal mines.
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