Search

Zinc-ion batteries (ZIBs) have attracted significant attention owing to their high safety, high energy density, and low cost. ZIBs have been studied as a potential energy device for portable and flexible electronics. Here, a highly flexible free-standing Zn anode is fabricated using a simple spin-coating technique, and its application in ZIBs is demonstrated. The free-standing Zn anode precursor is formed by mixing Zn particles with carbon nanotubes and poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP). The hexafluoropropylene group in PVDF-HFP improves the mechanical properties of the free-standing Zn anode, whereas the carbon nanotubes created percolation conduction in the composite electrode, leading to an increased electrical conductivity of the anode. Owing to the excellent electrical conductivity and high specific surface area of the free-standing Zn anode, ZIBs with high capacity, rate performance, and mechanical flexibility are achieved. The volumetric energy density of the ZIBs reaches 8.22 mW h cm-3 with a battery thickness of 0.4 mm. This work demonstrates that free-standing Zn anodes are promising anodes for flexible ZIBs.

Here we demonstrate a magnetic resonance coupling based wireless triboelectric nanogenerator (TENG) and fully self-powered wireless sensors. By integrating a microswitch and an inductor with the TENG, the pulsed voltage output is converted into a sinusoidal voltage signal with a fixed frequency. This can be transmitted wirelessly from the transmit coil to the resonant-coupled receiver coil with an efficiency of 73% for a 5 cm distance between the two coils (10 cm diameter). Analytic models of the oscillating and coupled voltage signals for the wireless energy transfer are developed, showing excellent agreement with the experimental results. A TENG of 40 × 50 mm2 can wirelessly light up 70 LEDs or charge up a 15 μF capacitor to 12.5 V in ~90 s. The system is further utilized for two types of fully self-powered wireless chipless sensors with no microelectronic components. The technologies demonstrate an innovative strategy for a wireless ‘green’ power source and sensing., Renewable energy based wireless power transfer is challenging. Here the authors show a resonant-coupled triboelectric nanogenerator as a wireless power source and have further utilized this system to explore two fully self-powered wireless chipless sensors.

Magnetic nanomaterials are promising adsorbents for their superior performance in the elimination of radioactive ions from aqueous solution. In this study, a new kind of fluorescent carbon dots were successfully introduced into MnFe2O4 to fabricate magnetic polyethyleneimine-functionalized carbon quantum dots/MnFe2O4 (PECQDs/MnFe2O4) nanocomposites by a simple hydrothermal method, which combined the fluorescent characteristic of CQDs, adsorption capacity of polyethyleneimine and magnetic separation property of MnFe2O4. Detailed characterization certified the formation of nanohybrid composites and its integrating advantages of fluorescence property and magnetism separation, which demonstrated its potential in immobilizing U(VI) and monitoring the adsorption process simultaneously in wastewater. The obtained PECQDs/MnFe2O4 was applied to remove U(VI) from aqueous solution and showed superior construction stability and adsorption capacity of 194 mg/g. Moreover, the kinetic and thermodynamic results suggested that the immobilization of U(VI) was an endothermic and spontaneous multilayer adsorption dominated process. In the end, the cation exchange and interaction between uranyl ions and abundant functional groups (i.e., NH2, OH and COOH) on PECQDs/MnFe2O4 were revealed to be responsible for the enhanced adsorption of U(VI), which was realized by forming outer-sphere surface complexes in the removal process. This study proposed an ultrafast-kinetics and high-efficiency adsorbent for U(VI) sequestration, which has a great application potential due to its outstanding recycling performance.

Liquid metal (LM) has been used as flexible electrodes for high performance triboelectric nanogenerators (TENGs), however it is unclear how the LM in tribo-layers would affect the performance of TENGs. Here, we report the investigation on the effects of LM particles incorporated into a tribo-layer on the performance of TENGs. The TENGs consist of a polyacrylonitrile (PAN) electrospinning nanofiber membrane, and a polytetrafluoroethylene (PTFE) thin film. LM particles with different concentrations are incorporated into PAN polymer matrix, and used to make the PAN nanofibers membranes by electrospinning. Result shows that the outputs of TENGs become much larger with the increase in LM content. Specifically, the current density increases by about 40%, and both the charge density and output voltage increase by nearly 70%. The overall output power is approximately 2 times higher for the TENG with 1.5 wt% LM concentration, as compared to those of TENGs with pure PAN tribo-layer. However, the output of PAN/LM-PTFE TENGs deteriorates drastically when the LM mass content is increased to 2.5 wt%, at which the composite contains a high density of LM spheroid and spindle particles, deteriorating the generation of triboelectric charge.

In spite of the high-brightness of perovskite quantum dots (QDs), their instability and sensitive to oxygen and moisture are still major challenges that obstruct their analytical applications. This work demonstrates the fabrication and application of perovskite CsPbBr3 QDs embedded in a molecularly imprinted polymer (MIP) for specific and sensitive detection of phoxim in real samples. CsPbBr3 QDs were obtained via a simple and convenient hot injection method. Based on the chemical structure of phoxim, we designed and synthesized a siloxane functional monomer with multiple functional groups to allow various types of interactions with phoxim. Next, the MIP/QDs composites were synthesized by slowly hydrolyzing the organosilicon monomers in situ. The obtained MIP/QDs composites possessed excellent selectivity for phoxim, and the imprinting factor of the optimized MIP/QDs was 3.27. Compared with previous studies regarding the detection of organophosphorus pesticides, the MIP/QDs fluorescence sensor exhibited high sensitivity and specificity. Under optimal conditions, the fluorescence quenching of the MIP/QDs had a good linear correlation for phoxim in the concentration range of 5–100 ng/mL, and with a limit of detection of 1.45 ng/mL. Finally, the method was used for the detection of phoxim in potato and soil samples, achieving recoveries of 86.8–98.2%.

This paper describes an alternative strategy for the preparation of highly ordered molecularly imprinted mesoporous silica microspheres (MIMSM) for the selective fluorescence sensing of sparfloxacin in biological samples. We designed and synthesized a new functional monomer through the thiol-ene click chemistry reaction of 3-(methacryloyloxy) propyltrimethoxysilane and 3-mercaptopropionic acid. Sparfloxacin was selected as a template, and Mn-doped ZnS quantum dots served as the signal transducing element. This one-pot strategy was used to fabricate the MIMSM. Fourier transform infrared spectroscopy demonstrated successful embedding of a functional monomer in the mesoporous silica microspheres, and the highly ordered, periodic hexagonal mesoporous structure of MIMSM was confirmed with small angle X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption measurements. The fluorescence intensity of the MIMSM had linear correlation with 0.05–2.0 μg/mL sparfloxacin. There was a rapid response time and excellent selectivity for structural analogues. Under optimal conditions, the limit of detection was 0.012 μg/mL for sparfloxacin. This method was then used with serum samples to achieve recoveries of 88.8–102%.

The leakage of radionuclides poses a great threat to the global ecosystem, which has aroused world-wide continuous attention. Since sorption plays the most important role in their environmental fate and humic acid (HA) is a key factor to their migration behavior, it is necessary to develop highly-efficient adsorbents that can remove radionuclides from the contaminated water in the presence of HA. Herein, we reported a novel multi-shelled Fe3O4@MnOx, which showed considerable sorption capacities towards uranium (U(VI)) and europium (Eu(III)). From the systemic batch experiments, the sorption kinetics follows the pseudo-second-order model, and sorption thermodynamics are endothermic processes. The sorption edges are pH-dependent but independent of ionic strength. Furthermore, the sorption isotherms are well described by the Langmuir model, giving maximum sorption capacities of 106.72 mg·g−1 for U(VI) and 138.13 mg·g−1 for Eu(III) at 298 K. Based on the spectroscopic studies, U(VI) is mainly adsorbed on the MnIII-O-H site while Eu(III) shows higher affinity to the MnIV-O-H site. In the presence of humic acid (HA), the HAUO2+ and (HA)2Eu+ species can accelerate the sorption kinetics and enhance the sorption capacities. This work can not only boost the exploration of adsorbent systems in the field of materials, but also promote the investigations of the interface reaction mechanism in the field of radiochemistry.

Stable and reliable electrical properties of interconnects and interfaces between flexible/stretchable and rigid materials/components are essential for the practical applications of flexible electronic devices and systems; traditional metal thin films and hard solder interconnects and interfaces can no longer meet these requirements. As an emerging soft conductive material, liquid metal has the advantages of high stretchability, flexibility, etc. over other soldering materials, and it has been used in interconnects and interfaces for some flexible electronics. In this study, we report a detailed investigation on the reliability and stability of liquid metal-based interconnects/interfaces under various mechanical deformations, including extension, bending, torsion, high frequency vibration and high temperature operation; we also compared the results with those of interconnects and interfaces using silver paste, the most commonly used solder for flexible electronics. The results show that liquid metal interconnects and interfaces maintain high conductivity under severe elongation up to 95% and 130%, upon bending with a curvature radius as low as ∼1.5 mm, and upon twisting up to 360°; meanwhile, interconnects and interfaces with silver paste filler lose electrical conductivity at elongations of 0.6% and 60%, respectively. Liquid metal interconnects and interfaces show superior performance to silver paste interconnects and interfaces because liquid metal can be re-shaped to make good contact with objects, while the silver paste becomes solid and rigid once dried and thus loses contact with other objects under deformation.

Perovskite-based photodetectors have great potential in light-signal conversion; the suppression of the dark current is regarded as one of the main concerns within the academic research communities to achieve a high-performance photodetector. Interfacial engineering in the transport layer is considered as one of the most essential methods for enhancement of perovskite photodetectors. Here, a nanocomposite thin film of tetra-sulfonated copper phthalocyanines and reduced graphene oxide (TS-CuPc/rGO) was investigated as the interfacial layer in perovskite-based photodetectors. Photodetectors with the TS-CuPc/rGO thin film as the interfacial layer exhibited a low dark current density of 2.2 × 10−8 A cm−2 at bias of −0.1 V as well as high responsivity and detectivity of ∼357 mA W−1 and ∼4.2 × 1012 jones, respectively; moreover, we observed an ON/OFF ratio of 7.33 × 103 to 520 nm light with an intensity of ∼0.077 mW cm−2. Our study revealed that with rGO additives, TS-CuPc molecules were favorable for the formation of an edge-on stacking film with high crystallinity. The rGO-induced crystalline TS-CuPc thin film with lower crystallographic defects effectively reduced the carrier recombination rate at the interfaces, leading to a suppressed dark current and enhanced photocurrent in the photodetector device, when compared to the less crystalline TS-CuPc layer.

Uranium, a kind of strategic resource for nuclear energy, is inevitably released into environment because of nuclear fuel fabrication and ore mining. Although numerous traditional materials have been applied for the removal of radionuclides, the integrating advantages of ultrafast adsorption kinetics and high adsorption capacity are still an extreme challenge. Herein we reported a facile strategy for fabricating a novel porous Al2O3 microsphere (P-Al2O3 MSs) by the calcination of metal–organic frameworks (MIL-53(Al)) and applied it to immobilize radionuclides from wastewater. The resulting P-Al2O3 MSs inherited the morphology of MIL-53(Al) and manifested a mesoporous structure with high specific area (∼248.57 m2·g−1). Kinetic analyses denoted that U(VI)/Eu(III) adsorption onto P-Al2O3 MSs achieved equilibrium within 25 min, much shorter than the commercial γ-Al2O3 nanomaterials. The calculated maximum adsorption amounts of P-Al2O3 MSs at 298 K reached 316.87 mg·g−1 for U(VI) (pH = 5.0) and achieved 223.37 mg·g−1 for Eu(III) (pH = 6.0), much higher than γ-Al2O3 and most of other functionalized metal oxides. XPS analysis indicated that the hydroxy groups played a necessary part role for the binding of U(VI) and Eu(III) to P-Al2O3 MSs. Moreover, the excellent adsorption capabilities for U(VI) and Eu(III) in natural or synthetic waters further confirmed the practical application of P-Al2O3 MSs in real wastewater treatment.

Platinum (Pt) gratings on langasite (LGS) substrates are a widely used structures in high temperature surface acoustic wave (SAW) devices. Multiple modes can be excited in Pt/LGS SAW devices owing to the heavy weight of the Pt electrode and leaky waves in the LGS substrate. In this work, we report on a detailed mode analysis of Pt/LGS SAW devices, where three commonly used LGS cuts are considered. A three-dimensional (3D) finite element method (FEM) numerical model was developed, and the simulation and experiment results were compared. The experiment and simulation results showed that there are two modes excited in the Pt/LGS SAW devices with Euler angle (0&deg, 138.5&deg, 27&deg, ) and (0&deg, 117&deg, ), which are Rayleigh-type SAW and SH-type leaky wave, respectively. Only the Rayleigh-type mode was observed in the Pt/LGS SAW devices with Euler angle (0&deg, 72&deg, ). It was found that the acoustic velocities are dependent on the wavelength, which is attributed to the change of wave penetration depth in interdigital transducers (IDTs) and the velocity dispersion can be modulated by the thickness of the Pt electrode. We also demonstrated that addition of an Al2O3 passivation layer has no effect on the wave modes, but can increase the resonant frequencies. This paper provides a better understanding of the acoustic modes of Pt/LGS SAW devices, as well as useful guidance for device design. It is believed that the Rayleigh-type SAW and SH-type leaky waves are potentially useful for dual-mode sensing applications in harsh environments, to achieve multi-parameter monitoring or temperature-compensation on a single chip.

The increased public concerns on healthcare, the environment and sustainable development inspired the development of biodegradable and biocompatible electronics that could be used as degradable electronics in implants. In this work, a fully biodegradable and flexible resistance random access memory (RRAM) was developed with low-cost biomaterial gelatin as the dielectric layer and the biodegradable polymer poly(lactide-coglycolide) acid (PLGA) as the substrate. PLGA can be synthesized by a simple solution process, and the PLGA substrate can be peeled off the handling substrate for operation once the devices are fabricated. The fabricated memory devices exhibited reliable nonvolatile resistive switching characteristics with a long retention time over 104 s and a near-constant on/off resistance ratio of 102 even after 200 bending cycles, showing the promising potential for application in flexible electronics. Degradation of the devices in deionized water and in phosphate buffered saline (PBS) solution showed that the whole devices can be completely degraded in water. The dissolution time of the metals and the gelatin layer was a few days, while that for PLGA is about 6 months, and can be modified by changing the synthesis conditions of the film, thus allowing the development of biodegradable electronics with designed dissolution time.

This paper reports a novel flexible film bulk acoustic resonator (FBAR) based on -phase polyvinylidene fluoride (PVDF) piezoelectric polymer. The proposed device was simulated and evaluated, then, a low-temperature photolithography process with a double exposure method was developed to pattern the electrodes for the device, which enabled the device to retain the piezoelectric properties of the -phase PVDF film. Results showed that the &beta, phase PVDF FBARs had a resonant frequency round 9.212 with a high electromechanical coupling coefficient () of 12.76% &plusmn, 0.56%. The device performed well over a wide bending-strain range up to 2400 owing to its excellent flexibility. It showed good stability as a strain sensor with a sensitivity of 80 , and no visible deterioration was observed after cyclic bending tests. The PVDF FBAR also exhibited an exceptionally large temperature coefficient of frequency (TCF) of &minus, 4630 , two orders of magnitude larger than those of other FBARs based on common inorganic piezoelectric materials, extraordinarily high sensitivity for temperature sensing. All results showed that -phase PVDF FBARs have the potential to expand the application scope for future flexible electronics.

This paper describes an alternative strategy for fabricating a fluorescent aptamer functionalized molecularly imprinted polymer (MIP) for highly specific sensing of kanamycin. The technique provides surface imprinting in aqueous solutions using CdSe quantum dots as supports, thiols modified aptamer and methacrylic acid as functional monomers, and kanamycin as a template. The MIP would function utilizing double recognition of the aptamer and imprinted cavities for fluorescent sensing of kanamycin. The “thiol-ene” click reaction was utilized to fix the aptamer into polymer matrix, and the click chemistry used was highly efficient under mild condition and environmentally friendly. Experimental results indicated that there was a synergistic interaction between the aptamer and MAA, which improved the recognition ability of MIP toward kanamycin. The MIP showed an imprinting factor of 3.51 for kanamycin, excellent analog selectivity, and strong resistance toward ions interference. The fluorescence intensity of the MIP enhanced gradually with increase in the concentration of kanamycin, and exhibited good linear correlation within the concentration of 0.05–10.0 μg/mL with a detection limit of 0.013 μg/mL. This fluorescent MIP was further applied to quickly, sensitively and simply sensing of kanamycin in food, water and biological samples which yielded satisfied results.

Uranium has attracted sustained attention due to its high mobility and biotoxicity. Among various techniques, sorption is considered as the most effective technique to treat the U(VI)-containing wastewater. In serving for low-cost adsorbents, layered double hydroxides (LDHs) have been proved to be promising candidates. However, the interaction mechanism of U(VI) with LDHs is still unclear, although plenty of LDHs have been used in this field. Herein, we developed two novel methods to fabricate ternary LDHs (MgFeAl LDHs and NiFeAl LDHs) and applied the ternary LDHs as adsorbents to investigate their sorption performance towards U(VI). The results showed that the sorption was endothermic and followed the pseudo-second-order kinetics through the formation of inner-sphere surface complexes, and the sorption isotherms were simulated by the Langmuir model well. Furthermore, systematic spectroscopy characterization indicated that the sorption occurred on the surface sites of Mg-OH and Ni2+–OH, while the CO32− in the gallery space also played an important role. This work highlighted the synthesis of high-efficient materials and their application in wastewater treatment.

Biomaterials gelatin is used as the dielectric layer in this work to develop metal/gelatin/Tungsten (W) RRAM devices, with silver (Ag), copper (Cu), W, and gold (Au) as the top electrode (TE) to study the effects of electrode metals on device characteristics. All types of the RRAM devices exhibit bipolar resistive switching characteristics with diverse performances. The work function difference between the TE and bottom electrode (BE) metals is found to play a profound role in determining the characteristics of the devices and even reversing the set and reset processes. The devices with larger work function difference between the TE and BE metals have higher and more stable on/off resistance ratio. The Ag/gelatin/W devices exhibit a relatively stable switching behavior with an on/off resistance ratio of >102, while that with Au TE exhibits a reversed set and reset processes with a high on/off resistance ratio of >105 owing to the large positive work function difference between Au and W. Metallic conductive filaments are confirmed to be responsible for the switching behaviors of the devices experimentally, and what metal element in the conductive filaments is determined by the work function difference of the metals used for the top and bottom electrodes.

Crossbar structural resistive switching devices (memristors) are fabricated using biomaterial gelatin film as the dielectric layer. The performance of the devices and the effects of gelatin film thickness and baking temperature are investigated. Results show that the optimal gelatin film thickness for the memristors is ∼80 nm and baking temperature is ∼105 °C. The optimized memristors show a bipolar resistive switching behavior with the resistance ratio between the high-resistance state and low-resistance state over 102, the retention time over 106 s without any obvious deterioration, and excellent stability and reliability, demonstrating its good potential for applications. A conductive atomic force microscopy is used to study the conductivity of the gelatin films under various biases, and the results indicate that the conductive filaments are responsible for the resistive switching behavior of the gelatin-based memristors.

The toxicity and radioactivity of uranium [235,238U(VI)] has resulted in serious environmental issues in recent years. Polyethyleneimine-decorated waste fly ash (FA@PEI) from thermal power plants has been fabricated via a novel and cost-efficient method and applied to the U(VI) elimination from aqueous solutions by batch experiments. The U(VI) removal was found to be dramatically influenced by pH whilst being ionic strength-independent, which indicated that the interaction was primarily controlled by inner-sphere surface complexation. Kinetic studies showed that the FA@PEI had an ultrafast removal rate (1.5 h to achieve adsorption equilibration) for U(VI) and a pseudo-second-order model fitted the adsorption process. The maximum removal capacity of U(VI) by FA@PEI was 70.3 mg g−1 at 298 K and pH 5.0. Based on the thermodynamics data (ΔH° > 0, ΔS° > 0 and ΔG° < 0), the U(VI) removal process is typically spontaneous and endothermic. According to the XPS analysis, the enhanced U(VI) adsorption was mainly attributed to the abundant metal–oxide bonds and amine groups (–NH2, –NH–). Furthermore, the FA@PEI material also demonstrated an outstanding regeneration ability. This paper highlights FA@PEI as an environmentally-friendly and economical alternative for U(VI) elimination from waste water.

This paper demonstrates the development and validation of a high-performance liquid chromatography (HPLC) method for the determination of pyrimethamine in fish and plasma samples using core–shell molecularly imprinted polymers (MIPs). The MIPs were synthesized based on thiol–ene click chemistry, using pentaerythritol tetra (3-mercaptopropionate) and dipentaerythritol pentaacrylate as binary cross-linkers, pyrimethamine as a template and methacrylic acid as a functional monomer. The MIPs were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The MIPs were used as matrix solid-phase dispersion extraction sorbents for the separation of pyrimethamine in fish and plasma samples. The results show that the developed MIPs had higher extraction capacity toward pyrimethamine than non-imprinted polymers (NIPs), high selectivity among pyrimethamine analogues, and a saturation capacity of 41.9 μmol g−1. Furthermore, the proposed method was validated for linearity, precision, accuracy, and it has been applied for the analysis of pyrimethamine in fish and plasma samples, obtaining satisfactory recoveries.

In the past few decades, uranium (235, 238U(VI)) has turned into a forefront environmental issue due to its extensive use in the nuclear industry and its toxicity and radioactivity. Herein, nanoscale zero valent iron (nZVI), which was supported on Ca–Mg–Al-layered double hydroxide (Ca–Mg–Al-LDH/nZVI), was fabricated via an in situ growth route and employed for U(VI) decontamination from aqueous solutions. Spectroscopy and microscopy (SEM, TEM, FTIR, XRD, BET, and XPS) technologies were applied for the investigation of the properties of Ca–Mg–Al-LDH/nZVI and the U(VI) elimination mechanism. Ca–Mg–Al-LDH/nZVI had a remarkable BET surface (426.8 m2 g−1), abundant functional groups (i.e., Fe–O, Al–O, –OH, etc.), high efficiency (4 h to achieve equilibrium) and large adsorption capacities (Qmax = 216.1 mg g−1) for U(VI) removal. The decontamination process of U(VI) was observed to be pH-dependent and ionic strength-independent, suggesting that the adsorption was predominated by inner-sphere surface coordination. XPS spectroscopy analyses indicated that the reduction and adsorption of nZVI and the adsorption of Ca–Mg–Al-LDH dominated U(VI) elimination on Ca–Mg–Al-LDH/nZVI. The environmentally friendly synthesis method, excellent physicochemical properties and remarkable removal performance suggested that Ca–Mg–Al-LDH/nZVI was applicable as a potential adsorbent for U(VI) decontamination from wastewater in environmental pollution remediation.

Development of a highly efficient material with large specific area was scientifically and technologically important for simultaneous elimination of inorganic and organic pollutants from wastewater. In this work, layered-double-hydroxides-coated (LDHs-coated) hollow carbon microsphere composites (HCMSs; LDHs/HCMSs) were fabricated using carbon spheres as templates via a hydrothermal method and were then applied for mutual removal of Pb(II) and humic acid (HA) under various experimental conditions, i.e., pH, ionic strength, contact time, addition sequences, and coexisting ions. The results indicated that the copresence of Pb(II) and HA facilitated single target pollutant [Pb(II) or HA] adsorption at pH < 8.0. The adsorbed HA was responsible for the improvement of Pb(II) adsorption, primarily as a result of the formation of HA-Pb-LDHs/HCMSs ternary complexes. Competitive adsorption of Cu(II), Co(II), Pb(II), and Ni(II) ions on LDHs/HCMSs was also investigated, and the LDHs/HCMSs had the affinity in the orde...

In this paper, the defective TiO2−x with abundant oxygen vacancies were fabricated through a simple modified solvothermal strategy and characterized by SEM, TEM, XRD, FT-IR, EDX, Zeta-potential, and XPS techniques in detail. The prepared TiO2−x was applied to remove U(VI) and humic acid (HA) from aqueous solutions to evaluate its sorption performance. The sorption of U(VI) and HA on TiO2−x was examined under various environmental conditions (e.g., contact time, pH, ionic strength, initial HA/U(VI) concentrations, the addition sequences of HA/U(VI) and temperature). According to the Langmuir model simulation, the maximum sorption capacities of U(VI) and HA on TiO2−x at pH = 5.0 were calculated to be 65 and 142 mg g−1, respectively, which were higher than most current reported materials. The kinetic results indicated that the sorption of U(VI) and HA onto TiO2−x was better described by the pseudo-second-order kinetic model. The presence of HA enhanced U(VI) sorption on TiO2−x at pH = 5.0, meanwhile, the surface adsorbed U(VI) on TiO2−x also enhanced the sorption capacity of HA, which was mainly attributed to the formation of U(VI)-HA-TiO2−x ternary complexes. Combining FT-IR and XPS analysis, the oxygen vacancies could provide high chemical activity and trap U(VI) in the defective sites of TiO2−x, while the sorption of HA was dominated by surface complexation. The findings might provide an opportunity to estimate and optimize the efficient simultaneous elimination of radionuclides and natural organic substances by using defective TiO2−x.

In this paper, we reported an environmental friendly and cost-effective method to prepare magnetic nanoparticles decorated tea waste (Fe3O4-tea) composites by chemical co-precipitation of Fe3+/Fe2+ on waste tea leaves. Various physical and chemical characterizations indicated that the synthetic Fe3O4 nanoparticles were combined to the tea powder surface by chemical bonds. When tested as an adsorbent for Cu(II) and Zn(II) removal, the Fe3O4-tea composites showed an unexpected high sorption capacity and satisfactory regeneration performance, better than those of naked Fe3O4 and other reported materials. The results showed that the maximum sorption capacities of Fe3O4-tea calculated from Langmuir isotherm model were 95.44 mg g−1 for Cu(II) and 68.78 mg g−1 for Zn(II) at pH 6.0. Interestingly, it was found that much higher adsorption capacity was achieved for Cu(II) on Fe3O4-tea rather than that for Zn(II) adsorption, which was attributed to the higher ionic potential of Cu(II), preferably penetrating into smaller pores. Furthermore, in the binary-solute system, Cu(II) exhibited greater inhibition for Zn(II) sorption, suggesting stronger affinity of Fe3O4-tea for Cu(II). Relatively, pseudo-second-order equation was the optimal model to describe the kinetics of Cu(II) and Zn(II) sorption, suggesting a chemisorption with the adsorption mechanism via M-O or M-N bonding. X-ray photoelectron spectroscopy (XPS) analysis showed that the enrichment of Cu(II) and Zn(II) was attributed to the abundant binding sites (e.g., –OH, –COOH and –NH groups) of Fe3O4-tea, which made stable complex compound with Cu2+ or Zn2+. This work provides a facile and general approach to synthesize promising magnetic biochar materials for wastewater treatment.

Atomic layer deposited (ALD) ultra-thin alumina film is proposed to control the operational lifetimes of fully biodegradable (FB-) surface sensitive surface acoustic wave (SAW) devices. SAW devices encapsulated with conventional thick organic materials fail to function effectively, while devices with an ultra-thin alumina encapsulation layer (AEL) function normally with high performance. After being subjected to degradation in water, a FB-SAW device with no AEL starts to degrade immediately and fails within 8 h, due to dissolution of the tungsten electrode and piezoelectric material (ZnO). The coating of an ultra-thin AEL on the surfaces prevents SAW devices from undergoing degradation in water and enables SAW devices to perform normally before the AEL is dissolved. The stable operation lifetimes of SAW devices are linearly dependent on the AEL thickness, thus allowing for the design of devices with precisely controlled operational lifetimes and degradation times. The results show that all the materials used could be degraded; also, in vitro cytotoxicity tests indicate that the encapsulated FB-SAW devices are biocompatible, and cells can adhere and proliferate on them normally, demonstrating great potential for broader biodegradable electronic device applications.

Manipulating biological cells or microparticles in three dimensions (3D) is invaluable for many biomedical applications, and recently effective and rapid manipulations of microparticles in 2D and 3D within microchannels or chambers using surface acoustic waves (SAWs) with bulk piezoelectric materials have been reported. However, these are generally expensive, or brittle and cannot be easily integrated into a single lab-on-chip. In this paper, we realized microparticle/cell patterning and 3D manipulation of yeast cells inside a chamber with a height of 1 mm using thin film ZnO/Si SAW devices. Effects of SAW frequency, channel width and thickness on alignment of microparticles were firstly investigated, and positions of the microparticles in the direction of SAW propagation can be controlled precisely by changing the phase angle of the acoustic waves from the ZnO/Si SAW device. A numerical model has been developed to investigate the SAW acoustic field and the resulted 3D motions of microparticles under the acoustic radiation forces within the microchamber. Finally, we realized and observed the 3D patterning of yeast cells within the microchannel. Our work shows a great potential for acoustofluidic, neural network research and biomedical applications using the ZnO/Si SAW devices. Accepted version

Design and fabrication of materials with abundant functional groups represent an important and promising direction in the remediation of aqueous contaminants. In recent years, carbon-based materials have drawn widespread concern on account of their low cost, large specific surface area, good chemical stability as well as controllable porosity. The U(VI) binding onto raw carbon-based materials is still confronted with the problem of limited adsorption capacity, which severely hinders the practical applications of materials. Herein, amino- and carboxyl-functionalized carbonaceous spheres (denoted as ACSs and CCSs) were fabricated by in-situ polymerization and simply annealing methods, respectively. The highest adsorption amounts of ACSs and CCSs towards U(VI) were calculated to be 73.83 and 401.61 mg·g−1 from Langmuir model at pH = 4.0 and 298 K, which were higher to that of raw carbonaceous material (19.31 mg·g−1). Interestingly, the Freundlich model could well simulate U(VI) sorption isotherms on ACSs at these temperatures (T = 298, 313 and 328 K), while U(VI) sorption isotherms on CCSs were able to significantly conform to the Langmuir model. According to FT-IR and XPS analysis, U(VI) was enriched on both materials on account of the ample functional groups on ACSs (e.g. C NOH/C NH2) and CCSs (e.g. OH/COOH). In addition, effect of ionic strength manifested that U(VI) elimination on ACSs and CCSs were greatly caused by the formation of outer-sphere and inner-sphere surface complexes, respectively. This work promises to provide two facile approaches for engineering diverse functionalized materials towards a highly rapid and efficient sequestering U(VI) from contaminated water.

The hexagonal boron nitride nanosheets (BNNSs) are one of the 2-dimensional(2D) materials, and have been explored for their applications in nanoelectronics etc, owing to their unique properties. Here, BNNSs are utilized to develop a high-performance hybrid piezo/triboelectric nanogenerator (PTEG). BNNSs of a few percentages in weight are incorporated into polydimethylsiloxane (PDMS) to form composites that are able to produce piezoelectric voltages up to ~ 5.4 V with d 33 ~ 12 pC/N. A PTEG composed of BNNS-PDMS and polyamide-6 (PA6) membranes ( 20 × 20 mm 2 ) demonstrates a current density of ~ 230 mA m − 2 , an output voltage of ~ 1870 V and a maximum power density of ~ 103.7 W m − 2 , more than three times higher than those of the control PDMS/PA6 nanogenerator. Electric polarization of the BNNS-PDMS membranes can further enhance the output of PTEGs. Detailed investigation reveals that the dramatically enhanced performance originates from the synergy of piezoelectric effect of BNNSs and increased electron affinity of BNNS-PDMS membranes, demonstrates the excellent potential of BNNS-based PTEGs.

As a promising sustainable power source for intelligent electronics, triboelectric nanogenerator (TENG) has attracted remarkable attention and various strategies have been sought to improve its output performance. However, most of these approaches for triboelectric materials optimization only focus on either chemical composition modulation or surface microstructure fabrication. In this work, both aspects are considered and an effective strategy is proposed to construct high performance TENGs based on polyvinylidene fluoride (PVDF) via graphene nanosheets incorporation in conjunction with electrospinning technology. Hence, a 20 × 20 mm2 TENG comprising of PVDF/G nanofibers and polyamide-6 (PA6) films demonstrates superior triboelectric performance with an output voltage of ~1511 V, a short-circuit current density of ~189 mA m−2, and a maximum peak power density of ~130.2 W m−2, nearly eight times higher than that of the PVDF-PA6 TENG. Additionally, under impedance matching condition, the PVDF/G-PA6 TENG can harvest ~74.13 μJ energy per cycle, with a time-averaged output power density of 926.65 mW m−2. Detail investigation reveals that both composition modulation with graphene and nanofiber structure fabricated through electrospinning contribute to the triboelectric performance enhancement of PVDF/G NF films. This work provides an effective strategy of simultaneously optimizing the chemical composition and surface microstructure of triboelectric materials to significantly improve the output performance of TENGs, and to further promote the widespread application of TENGs.

Contact electrification has been a debatable topic in the last few years and newer theories have accounted for the recent developments. In recent times, triboelectricity is proposed to be a newer alternative among the ubiquitous energy resources which makes it indispensable to understand the technique in vivid details. Here in this research work, the dynamic triboelectric nature of materials under strain was observed and studied in detail. On account of this, soft material like nylon and Teflon tends to shift their respective positions on the triboelectric series scale upon the applied strain. The detailed investigation using advanced techniques allowed us to probe and discover new quasi-equilibrium states during the contact and separation cycle of nylon when contacted with aluminum oxide. The new results obsolete the existing static triboelectric series scale for the dynamic characterizations for the nanogenerator applications. Additionally, recent charge transfer models of contact electrifications were investigated in detail to probe the intricate mechanism further. Here, in this research, a novel self-powered nanoscale thickness monitoring system application is demonstrated with a resolution of 5 nm (for ALD grown aluminum oxide films). We believe this work will help the researchers to understand the contact-electrification phenomenon in detail.

Langasite (LGS) surface acoustic wave (SAW) temperature sensors have a large second order temperature coefficient of frequency, which leads to their non-linear and non-monotonic responses in a wide temperature range and possibly makes the measured temperatures non-unique for a specific sensor response. Here, we propose a high-temperature Pt/LGS SAW sensor with linear frequency–temperature behavior in a wide temperature range, which was fabricated on a LGS (0°, 138.5°, 72°) substrate. The sensor has a single acoustic mode, but dual resonances with similar second- and third-order temperature sensitivities that were utilized for achieving a linear frequency–temperature response by a method of difference. A linear relationship between the measured sensor output (Δfm21) and temperature was obtained in the range of −60 °C to 700 °C, consistent with the theoretical analysis. The sensor has a high sensitivity of −167 ppm/K for the whole temperature range. All the results demonstrated exciting prospects of the sensor for wide temperature monitoring in harsh environments.

The preparation of molecularly imprinted mesoporous silica with perovskite quantum dots (QDs) grown in situ and their applications for highly sensitive fluorescence sensing of 2,2-dichlorovinyl dimethyl phosphate (DDVP) is presented. Highly ordered mesoporous silica materials were synthesized and employed as solid supports. Uniform and highly luminescent CsPbBr3 QDs were grown in the pores of these mesoporous silica. Subsequently, surface graft imprinting was applied on the surface of the QDs-encapsulated mesoporous silica. The QDs were acted as a recognition signal transducer and the molecular imprinting process provided recognition sites for 2,2-dichlorovinyl dimethyl phosphate. The QDs grown in situ in SBA-15 mesopores greatly improved the sensitivity for the determination of 2,2-dichlorovinyl dimethyl phosphate. Under the optimized conditions, the QDs-encapsulated molecularly imprinted mesoporous silica was linear between the concentration of 5 and 25 μg/L for DDVP, and detection limit was 1.27 μg/L. The QDs-encapsulated molecularly imprinted mesoporous silica was subsequently applied to the fluorescence analysis of 2,2-dichlorovinyl dimethyl phosphate in cabbage and lettuce samples and achieved recoveries from 87.4% to 101%. The time-resolved photoluminescence decay and UV–vis spectroscopic studies indicated that the quenching mechanism on the fluorescence of the QDs can be attributed to charge transfer between the QDs and DDVP.

All-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I) have attracted considerable attention with superior electrical and photophysical properties. In this study, luminescent perovskite (CsPbBr3) quantum dots (QDs) as sensing elements combined with molecularly imprinted polymers (MIPs) are used for the detection of omethoate (OMT). The new MIPs@CsPbBr3 QDs were synthesized successfully through the imprinting technology with a sol–gel reaction. The fluorescence (FL) of the MIPs@CsPbBr3 QDs was quenched obviously on loading the MIPs with OMT, the linear range of OMT was from 50 to 400 ng/mL, and the detection limit was 18.8 ng/mL. The imprinting factor was 3.2, which indicated excellent specificity of the MIPs for the inorganic metal halide (IMH) perovskites. The novel composite possesses the outstanding FL capability of CsPbBr3 QDs and the high selectivity of molecular imprinting technology, which can convert the specific interactions between template and the imprinted cavities to apparen...

Triboelectric nanogenerators (TENGs), as a promising energy harvesting technology, have attracted considerable attention and various approaches have been developed to improve their output performance. An innovative strategy was proposed recently by using solid polymer electrolyte (SPE) with asymmetric pairing ions as the friction layer, showing excellent potential to achieve high-performance TENGs. However, it is far from clear what are the effects of SPE on TENG performance as only one electrolyte, CaCl2, was used for the investigation. Herein, PTFE/PVA-MClx TENGs based on SPEs with different types of electrolytes, including LiCl, ZnCl2, CaCl2, FeCl3, and AlCl3, were fabricated and their performances were investigated. All the devices demonstrated superior output performance than that of the control PTFE/PVA TENG. Specifically, the PTFE/PVA-LiCl TENG exhibited remarkably enhanced triboelectric performance with an output voltage of ~1345 V, a short-circuit current density of ~260 mA m−2 and a maximum power density of ~83 W m−2, four times higher than that of the control PTFE/PVA TENG. Detailed investigations revealed that in combination with improved triboelectric property, the enhanced interaction of SPEs with opposite triboelectric layers further significantly boost the triboelectric outputs. This work presents a new method to increase the interaction between triboelectric layers to effectively improve the outputs of TENGs, and to facilitate the development of high performance TENGs.

A flexible surface acoustic wave (SAW) strain sensor in the frequency range of 162–325 MHz was developed based on a single crystalline LiNbO3 thin film with dual resonance modes, namely, the Rayleigh mode and the thickness shear mode (TSM). This SAW sensor could handle a wide strain range up to ±3500 μe owing to its excellent flexibility, which is nearly six times the detecting range of bulk piezoelectric substrate based SAW strain sensors. The sensor exhibited a high sensitivity of 193 Hz/ μe with a maximum hysteresis less than 1.5%. The temperature coefficients of frequency, for Rayleigh and TSM modes, were −85 and −59 ppm/ °C, respectively. No visible deterioration was observed after cyclic bending for hundreds of times, showing its desirable stability and reliability. By utilizing the dual modes, the strain sensor with a self-temperature calibrated capability can be achieved. The results demonstrate that the sensor is an excellent candidate for strain sensing.