From typical electrical appliances to thriving intelligent robots, the exchange of information between humans and machines has mainly relied on the contact sensor medium. However, this kind of ...contact interaction can cause severe problems, such as inevitable mechanical wear and cross‐infection of bacteria or viruses between the users, especially during the COVID‐19 pandemic. Therefore, revolutionary noncontact human–machine interaction (HMI) is highly desired in remote online detection and noncontact control systems. In this study, a flexible high‐sensitivity humidity sensor and array are presented, fabricated by anchoring multilayer graphene (MG) into electrospun polyamide (PA) 66. The sensor works in noncontact mode for asthma detection, via monitoring the respiration rate in real time, and remote alarm systems and provides touchless interfaces in medicine delivery for bedridden patients. The physical structure of the large specific surface area and the chemical structure of the abundant water‐absorbing functional groups of the PA66 nanofiber networks contribute to the high performance synergistically. This work can lead to a new era of noncontact HMI without the risk of contagiousness and provide a general and effective strategy for the development of smart electronics that require noncontact interaction.
Flexible noncontact sensing based on a high‐sensitivity humidity sensor is realized by anchoring multilayer graphene (MG) into electrospun polyamide (PA) 66 for human–machine interaction systems, which can achieve not only asthma detection, via monitoring the respiration rate in real time, and remote alarm systems, but also touchless interfaces in medicine delivery for bedridden patients.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Fibrous materials usually have good mechanical, heat-resistant, acid-resistant, alkali-resistant and moisture regained properties which originate from its composition, condensed structure and ...crosslinking styles. However, these materials often lack of good electrical conductivity, flame retardance, anti-static and anti-radiation properties which are desired for varied specific applications. Graphene, as a new emerging nanocarbon material, has some unique properties including superb thermal and electrical conductivity, strong mechanical and anti-corrosive property, extremely high surface area etc. Therefore, graphene has attracted extensive interests in recent years. Upon modification with graphene, fibers exhibit a number of enhanced or new properties such as adsorption performance, anti-bacteria, hydrophobicity and conductivity which are beneficial for broader applications. In this review, the strategies to modify the fibers with graphene and the corresponding effects on the fibers as well as the relevant applications in varied areas were discussed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Effect of interdigital electrode gap size on the performance of capacitive humidity sensor was investigated.•SnO2-modified MoS2 nanocomposite was successfully synthesized.•Different humidity sensing ...mechanisms are analyzed in detail.
To improve the sensitivity of humidity sensors, the interdigital electrode size should be paid more attention, apart from the development of high performance sensing materials. This paper investigated the interaction between testing electrode and the performance of capacitive humidity sensor. To our best knowledge, no other reported papers have investigated it before. We found that the gap size of interdigital electrode had crucial influence on the response of SnO2/MoS2 based capacitive humidity sensors due to the different surface electrical conduction mechanisms. For the sensor with small gap interdigital electrode structure, the capacitance decreases exponentially as relative humidity (RH) rises so that high sensitivity is obtained at low humidity range (0%–45% RH). While the gap is wide enough, the capacitance increases exponentially as RH grows to get ultrahigh sensitivity at high humidity range (45%–90% RH). The experimental results show that the sensor with 5 μm gap have the largest sensitivity (161 μF/% RH) at low humidity range while the best sensitivity of 3170 pF/% RH is obtained at high humidity range for the sensor with gap of 100 μm. The as-prepared SnO2/MoS2 hybrid sensing nanocomposite was synthesized through a two-step hydrothermal route and its morphology and structure were further characterized using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). Moreover, the SnO2/MoS2 based capacitive humidity sensors have fast response, short recovery time, little hysteresis and good repeatability.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Novel nanomaterials and advanced nanotechnology continuously push forward the rapid development of sustainable energy conversion and storage equipment. An emerging family of two‐dimensional ...transition‐metal carbides, nitrides and carbonitrides, also known as MXenes, have attracted increasing attention and in depth investigation. Benefitting from their unique intrinsic properties, MXenes have attracted significant attention and they have been considered as promising candidate materials for the development of environmentally friendly energy resources. A large number of studies show that MXenes have great potential in energy conversion and storage fields. Despite of their exceptional properties, MXenes also have some inherent characteristics, such as low capacities and unstable retention performances, which severely hinder their prospect applications in energy conversion and storage fields. In this Minireview, the latest progress on MXenes and their hybrid composites with small molecules, polymers, carbon or metal ions, and their applications in energy conversion and storage fields is highlighted, including their use in different types of batteries, supercapacitors, hydrogen/oxygen evolution reactions, electromagnetic interference absorption/shielding and solar steam generation. In addition, the critical challenges and further development prospects of MXene‐based materials are also introduced.
Recent advancements in the preparation of MXene‐based nanocomposites for various energy storage applications are reported. Critical challenges and further development prospects of MXene‐based materials are also discussed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Electrochemical water splitting is a clean and sustainable process for hydrogen production on a large scale as the electrical power required can be obtained from various renewable energy resources. ...The key challenge in electrochemical water splitting process is to develop low‐cost electrocatalysts with high catalytic activity for the hydrogen evolution reaction (HER) on the cathode and the oxygen evolution reaction (OER) on the anode. OER is the most important half‐reaction involved in water splitting, which has been extensively studied since the last century and a large amount of electrocatalysts including noble and non‐noble metal‐based materials have been developed. Among them, transition metal borides and borates (TMBs)‐based compounds with various structures have attracted increasing attention owing to their excellent OER performance. In recent years, many efforts have been devoted to exploring the OER mechanism of TMBs and to improving the OER activity and stability of TMBs. In this review, recent research progress made in TMBs as efficient electrocatalysts for OER is summarized. The chemical properties, synthetic methodologies, catalytic performance evaluation, and improvement strategy of TMBs as OER electrocatalysts are discussed. The electrochemistry fundamentals of OER are first introduced in brief, followed by a summary of the preparation and performance of TMBs‐based OER electrocatalysts. Finally, current challenges and future directions for TMBs‐based OER electrocatalysts are discussed.
Shake tree: The chemical properties, synthetic methodologies, catalytic performance evaluation, and urgent challenges and future directions of transition metal borides and borates (TMBs) as oxygen evolution reaction (OER) electrocatalysts are discussed.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Carbon and graphene quantum dots (CQDs and GQDs), known as zero-dimensional (0D) nanomaterials, have been attracting increasing attention in sensing and bioimaging. Their unique electronic, ...fluorescent, photoluminescent, chemiluminescent, and electrochemiluminescent properties are what gives them potential in sensing. In this Review, we summarize the basic knowledge on CQDs and GQDs before focusing on their application to sensing thus far followed by a discussion of future directions for research into CQDs- and GQD-based nanomaterials in sensing. With regard to the latter, the authors suggest that with the potential of these nanomaterials in sensing more research is needed on understanding their optical properties and why the synthetic methods influence their properties so much, into methods of surface functionalization that provide greater selectivity in sensing and into new sensing concepts that utilize the virtues of these nanomaterials to give us new or better sensors that could not be achieved in other ways.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Owing to the limitations of two-dimensional devices such as easily damaged and airtight characteristics in practical applications, flexible fiber electronics which can narrow the gap between devices ...and wearable applications due to their unique stitchable function have been attracting tremendous attention nowadays. Here, this paper introduced a simple strategy for fabricating the piezoelectric microfiber with a novel core-sheath structure by directly electrospinning the poly(vinydene fluoride-trifluoroethylene) (P(VDF-TrFE)) onto the flexible conductive wire. Precise control of the fiber diameter and thickness of P(VDF-TrFE) functional layer can be achieved. Specifically, this stitchable fiber exhibits high sensitivity of 60.82 mV/N and excellent durability of 15000 cycles under positive compression, and finite element method (FEM) was carried out cooperating with practical experiment to analyze the stress and electric field distribution of piezoelectric fibers under both positive compression and bending modes through COMSOL software. The flexible stitchable fiber can bear various complex, even severe deformations such as bending and knotting, enabling itself to be woven into textile and further generate power and response when subjected to external deformation, which is of significance for the portable and wearable electronics that are expected to be breathable and comfortable. This work also offers a general and effective solution for the flexible and wearable electronic devices.
Piezoelectric microfibers with a novel core-sheath structure were fabricated by directly electrospinning the P(VDF-TrFE) onto the flexible conductive wire. The flexible stitchable fiber exhibits high sensitivity of 60.82 mV/N and excellent durability of 15000 cycles and can narrow the gap between electronics and wearable applications. Display omitted
•An electrospinning core-sheath piezoelectric microfiber for self-powered stitchable sensor is proposed.•The piezoelectric microfiber can work under both positive compression and bending modes.•The stress and electric field distribution are analyzed by finite element method (FEM) through COMSOL software.•Detection for human motions by smart fibers incorporating textile is achieved.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A hierarchical core-shell heterostructure comprised of vertical and intercrossing ultrathin NiMn-LDHs nanosheets shell and slightly curly and tops tangled CuO nanowires core shows promising ...electrochemical storage properties.
Display omitted
•A hierarchical NiMn-LDH@CuO/CF core-shell heterostructure was successfully prepared.•The hybrid comprises of vertical NiMn-LDHs shell and tops tangled CuO nanowires core.•The NiMn-LDH@CuO/CF electrode exhibits high capacitance of 6077 mF cm−2 at 2 mA cm−2.•The blue LED indicator can be lit up eight minutes by three ASCs connected in series.
Supercapacitors are attracting tremendous research interest because they are expected to achieve battery-level energy density while having long calendar life and short charging time. Ultrathin layered double hydroxide nanosheets (LDHs) are promising candidates as electrode materials for energy storage. Herein, we have successfully designed and synthesized a hierarchical NiMn-LDH@CuO/CF core-shell heterostructure which comprises a vertical and intercrossing ultrathin NiMn-LDHs nanosheets shell and a slightly curly and tops tangled CuO nanowires core. The synthesized NiMn-LDH@CuO/CF electrode exhibits a high areal capacitance of 6077 mF cm−2 (2430.8 F g−1) at a current density of 2 mA cm−2 (0.8 A g−1), which is significant higher than those of CF, Cu(OH)2/CF, CuO/CF, NiMn-LDH/CF and NiMn-LDH electrodes. Moreover, a superior cycling stability of 89.22% retention after 8000 cycles at a high current density of 50 mA cm−2 is observed and a low internal resistance Rs (0.584 Ω) can be achieved. Furthermore, an all solid-state asymmetric supercapacitor (ASC) device based on the as-synthesized hierarchical NiMn-LDH@CuO/CF core-shell heterostructure hybrid material as positive electrode and activated carbon as negative electrode is successfully fabricated and exhibits an energy density of 10.8 W h kg−1 at a power density of 100 W kg−1. Additionally, a LED indicator can be lit up for eight minutes when three ASCs are connected in series. The excellent electrochemical performances can be credited to the significant enhancement of the specific surface area, charge transport and mechanical stability resulted from the ultrathin LDH shell, the highly conductive CuO nanowires core-shell nanostructure. This strategy for the fabrication of hierarchical core-shell heterostructure could have enormous potential for applications in high performance energy storage devices.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We report the cytocompatibility and regulating effects of the nanostructured reduced graphene oxide (rGO) microfibers, which are synthesized through a capillary hydrothermal method, on neural ...differentiation of neural stem cells (NSCs). Our findings indicate that the flexible, mechanically strong, surface nanoporous, biodegradable, and cytocompatible nanostructured rGO microfibers not only offer a more powerful substrate for NSCs adhesion and proliferation compared with 2D graphene film and tissue cluture plate but also regulate the NSCs differentiation into neurons and form a dense neural network surrounding the microfiber. These results illustrate the great potential of nanostructured rGO microfibers as an artificial neural tissue engineering (NTE) scaffold for nerve regeneration.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
This paper studied and realized a flexible nanogenerator based on P(VDF-TrFE) nanofibers and PDMS/MWCNT thin composite membrane, which worked under triboelectric and piezoelectric hybrid mechanisms. ...The P(VDF-TrFE) nanofibers as a piezoelectric functional layer and a triboelectric friction layer are formed by electrospinning process. In order to improve the performance of triboelectric nanogenerator, the multiwall carbon nanotubes (MWCNT) is doped into PDMS patterned films as the other flexible friction layer to increase the initial capacitance. The flexible nanogenerator is fabricated by low cost MEMS processes. Its output performance is characterized in detail and structural optimization is performed. The device's output peak-peak voltage, power and power density under triboelectric mechanism are 25 V, 98.56 μW and 1.98 mW/cm
under the pressure force of 5 N, respectively. The output peak-peak voltage, power and power density under piezoelectric working principle are 2.5 V, 9.74 μW, and 0.689 mW/cm
under the same condition, respectively. We believe that the proposed flexible, biocompatible, lightweight, low cost nanogenerator will supply effective power energy sustainably for wearable devices in practical applications.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
PDF