Fast Reaction Kinetics and Commendable Low-Temperature Adaptability of Zinc Batteries Enabled by Aprotic Water-Acetamide Symbiotic Solvation Sheath.

Although rechargeable aqueous zinc batteries are cost effectiveness, intrinsicly safe, and high activity, they are also known for bringing rampant hydrogen evolution reaction and corrosion. While eutectic electrolytes can effectively eliminate these issues, its high viscosity severely reduces the mobility of Zn2+ ions and exhibits poor temperature adaptability. Here, we infuse acetamide molecules with Lewis base and hydrogen bond donors into a solvated shell of Zn[(H2 O)6 ]2+ to create Zn(H2 O)3 (ace)(BF4 )2 . The viscosity of 1ace-1H2 O is 0.032 Pa s, significantly lower than that of 1ace-0H2 O (995.6 Pa s), which improves ionic conductivity (9.56 mS cm-1 ) and shows lower freezing point of -45 °C, as opposed to 1ace-0H2 O of 4.04 mS cm-1 and 12 °C, respectively. The acidity of 1ace-1H2 O is ≈2.8, higher than 0ace-1H2 O at ≈0.76, making side reactions less likely. Furthermore, benefiting from the ZnCO3 /ZnF2 -rich organic/inorganic solid electrolyte interface, the Zn || Zn cells cycle more than 1300 hours at 1 mA cm-2 , and the Zn || Cu operated over 1800 cycles with an average Coulomb efficiency of ≈99.8 %. The Zn || PANI cell cycled over 8500 cycles, with a specific capacity of 99.8 mAh g-1 at 5 A g-1 at room temperature, and operated at -40 °C with a capacity of 66.8 mAh g-1 .

Development and Assessment of Nano-Technologies for Cancer Treatment: Cytotoxicity and Hyperthermia Laboratory Studies.

Cancer treatment by magnetic hyperthermia offers numerous advantages, but for practical applications many variables still need to be adjusted before developing a controlled and reproducible cancer treatment that is bio-compatible (non-damaging) to healthy cells. In this work, Fe3O4 and CoFe2O4 were synthesized and systematically studied for the development of efficient therapeutic agents for applications in hyperthermia. The biocompatibility of the materials was further evaluated using HepG2 cells as biological model. Colorimetric and microscopic techniques were used to evaluate the interaction of magnetic nano-materials (MNMs) and HepG2 cells. Finally, the behavior of MNMs was evaluated under the influence of an alternating magnetic field (AMF), observing a more efficient temperature increment for CoFe2O4, a desirable behavior for biomedical applications since lower doses and shorter expositions to alternating magnetic field might be required.

Fluorescent MUA-stabilized Au nanoclusters for sensitive and selective detection of penicillamine.

In this study, we have developed a facile method for preparation of highly fluorescent Au nanoclusters (AuNCs) using 11-mercaptoundecanoic acid (MUA) as both the reducing and stabilizing agent. The as-prepared MUA functionalized AuNCs (MUA-AuNCs) have good water solubility, excellent photostability, and strong fluorescence emission at 610 nm with a quantum yield of 7.28% in water. The fluorescence of MUA-AuNCs was first quenched by copper ions through electron transfer, subsequently caused obvious restoration by competitive effect after adding penicillamine, making it a potential fluorescent sensor for penicillamine with a detection limit of 0.08 µM. Furthermore, the newly designed fluorescence "on-off-on" assay was explored for the measurement of penicillamine in complex real water and urine samples with satisfactory results.

Strongly fluorescent cysteamine-coated copper nanoclusters as a fluorescent probe for determination of picric acid.

This paper describes the synthesis of fluorescent copper nanoclusters (CuNC) with a fluorescence quantum yield as high as 2.3% after modification with cysteamine. The modified CuNC are shown to be viable probes for the determination of picric acid (PA). Fluorescence drops with increasing concentration of PA which can be detected fluorometrically with a 0.14 µM limit of detection. This is much lower than required by the People's Republic of China Surface Water Environmental Quality Standard (2.2 µM). The probe was successfully applied to the determination of PA in spiked tap water, lake water and river water. Graphical abstract Copper nanoclusters (CuNC) have weak fluorescence but after the modification with cysteamine, the fluorescence of CuNC is strongly enhanced. The fluorescence of such cysteamine-coated copper nanoclusters (CuNC-CA) is reduced upon the addition of picric acid (PA) through an inner filter effect (IFE).

Ratiometric determination of copper(II) using dually emitting Mn(II)-doped ZnS quantum dots as a fluorescent probe.

A ratiometric probe is described for the fluorometric determination of Cu(II) ions based on their quenching effect on the luminescence of dually-emitting quantum dots (QDs). ZnS QDs were doped with Mn(II) and subsequently modified with mercaptopropionic acid to give the QD probe which consists of a  sole fluorophore but has two emission peaks (at 430 and 590 nm under 310 nm excitation, respectively). On addition of Cu(II) ions, the 590 nm band is quenched while the 430 nm band exhibits a little change. The changes in the intensity ratios of the yellow and the purple bands increases linearly in the 0 to 3.0 µM Cu(II) concentration range, and the detection limit reached 14 nM. The QD probe was validated and successfully applied to the determination of Cu(II) in spiked real water samples. Graphical abstract Mn-doped ZnS (ZnS:Mn(II)) quantum dots were synthesized with yellow fluorescence. After the modification of 3-mercaptopropionic acid (MPA), ZnS:Mn(II) was transferred to aqueous phase and became MPA modified Mn-doped ZnS (MPA- ZnS:Mn(II)). The fluorescence was changed to purple upon the addition of copper ions because the yellow band was largely quenched while the purple band only changed a little.

Holotomography and atomic force microscopy: a powerful combination to enhance cancer, microbiology and nanotoxicology research.

Modern imaging strategies are paramount to studying living systems such as cells, bacteria, and fungi and their response to pathogens, toxicants, and nanomaterials (NMs) as modulated by exposure and environmental factors. The need to understand the processes and mechanisms of damage, healing, and cell survivability of living systems continues to motivate the development of alternative imaging strategies. Of particular interest is the use of label-free techniques (microscopy procedures that do not require sample staining) that minimize interference of biological processes by foreign marking substances and reduce intense light exposure and potential photo-toxicity effects. This review focuses on the synergic capabilities of atomic force microscopy (AFM) as a well-developed and robust imaging strategy with demonstrated applications to unravel intimate details in biomedical applications, with the label-free, fast, and enduring Holotomographic Microscopy (HTM) strategy. HTM is a technique that combines holography and tomography using a low intensity continuous illumination laser to investigate (quantitatively and non-invasively) cells, microorganisms, and thin tissue by generating three-dimensional (3D) images and monitoring in real-time inner morphological changes. We first review the operating principles that form the basis for the complementary details provided by these techniques regarding the surface and internal information provided by HTM and AFM, which are essential and complimentary for the development of several biomedical areas studying the interaction mechanisms of NMs with living organisms. First, AFM can provide superb resolution on surface morphology and biomechanical characterization. Second, the quantitative phase capabilities of HTM enable superb modeling and quantification of the volume, surface area, protein content, and mass density of the main components of cells and microorganisms, including the morphology of cells in microbiological systems. These capabilities result from directly quantifying refractive index changes without requiring fluorescent markers or chemicals. As such, HTM is ideal for long-term monitoring of living organisms in conditions close to their natural settings. We present a case-based review of the principal uses of both techniques and their essential contributions to nanomedicine and nanotoxicology (study of the harmful effects of NMs in living organisms), emphasizing cancer and infectious disease control. The synergic impact of the sequential use of these complementary strategies provides a clear drive for adopting these techniques as interdependent fundamental tools.

Aluminum enhances the oxidative damage of ZnO NMs in the human neuroblastoma SH-SY5Y cell line.

Bare and doped zinc oxide nanomaterials (ZnO NMs) are of great interest as multifunctional platforms for biomedical applications. In this study, we systematically investigate the physicochemical properties of Aluminum doped ZnO (AZO) and its bio-interactions with neuroblastoma (SH-SY5Y) and red blood (RBCs) cells. We provide a comprehensive chemical and structural characterization of the NMs. We also evaluated the biocompatibility of AZO NMs using traditional toxicity assays and advanced microscopy techniques. The toxicity of AZO NMs towards SH-SY5Y cells, decreases as a function of Al doping but is higher than the toxicity of ZnO NMs. Our results show that N-acetyl cysteine protects SH-SY5Y cells against reactive oxygen species toxicity induced by AZO NMs. ZnO and AZO NMs do not exert hemolysis in human RBCs at the doses that cause toxicity (IC50) in neuroblastoma cells. The Atomic force microscopy qualitative analysis of the interaction of SH-SY5Y cells with AZO NMs shows evidence that the affinity of the materials with the cells results in morphology changes and diminished interactions between neighboring cells. The holotomographic microscopy analysis demonstrates NMs' internalization in SH-SY5Y cells, changes in their chemical composition, and the role of lipid droplets in the clearance of toxicants.

Highly Efficient and Stable Organic Solar Cells Enabled by a Commercialized Simple Thieno[3,2-b]thiophene Additive.

Delicately manipulating nanomorphology is recognized as a vital and effective approach to enhancing the performance and stability of organic solar cells (OSCs). However, the complete removal of solvent additives with high boiling points is typically necessary to maintain the operational stability of the device. In this study, two commercially available organic intermediates, namely thieno[3,2-b]thiophene (TT) and 3,6-dibromothieno[3,2-b]thiophene (TTB) are introduced, as solid additives in OSCs. The theoretical simulations and experimental results indicate that TT and TTB may exhibit stronger intermolecular interactions with the acceptor Y6 and donor PM6, respectively. This suggests that the solid additives (SAs) can selectively intercalate between Y6 and PM6 molecules, thereby improving the packing order and crystallinity. As a result, the TT-treated PM6:Y6 system exhibits a favorable morphology, improved charge carrier mobility, and minimal charge recombination loss. These characteristics contribute to an impressive efficiency of 17.75%. Furthermore, the system demonstrates exceptional thermal stability (T80 > 2800 h at 65 °C) and outstanding photostability. The universal applicability of TT treatment is confirmed in OSCs employing D18:L8-BO, achieving a significantly higher PCE of 18.3%. These findings underscore the importance of using appropriate solid additives to optimize the blend morphology of OSCs, thereby improving photovoltaic performance and thermal stability.

Thermal evaporation-induced anhydrous synthesis of Fe3O4-graphene composite with enhanced rate performance and cyclic stability for lithium ion batteries.

We present a high-yield and low cost thermal evaporation-induced anhydrous strategy to prepare hybrid materials of Fe3O4 nanoparticles and graphene as an advanced anode for high-performance lithium ion batteries. The ~10-20 nm Fe3O4 nanoparticles are densely anchored on conducting graphene sheets and act as spacers to keep the adjacent sheets separated. The Fe3O4-graphene composite displays a superior battery performance with high retained capacity of 868 mA h g(-1) up to 100 cycles at a current density of 200 mA g(-1), and 539 mA h g(-1) up to 200 cycles when cycling at 1000 mA g(-1), high Coulombic efficiency (above 99% after 200 cycles), good rate capability, and excellent cyclic stability. The simple approach offers a promising route to prepare anode materials for practical fabrication of lithium ion batteries.

Inducing Fe 3d Electron Delocalization and Spin-State Transition of FeN4 Species Boosts Oxygen Reduction Reaction for Wearable Zinc-Air Battery.

Transition metal-nitrogen-carbon materials (M-N-Cs), particularly Fe-N-Cs, have been found to be electroactive for accelerating oxygen reduction reaction (ORR) kinetics. Although substantial efforts have been devoted to design Fe-N-Cs with increased active species content, surface area, and electronic conductivity, their performance is still far from satisfactory. Hitherto, there is limited research about regulation on the electronic spin states of Fe centers for Fe-N-Cs electrocatalysts to improve their catalytic performance. Here, we introduce Ti3C2 MXene with sulfur terminals to regulate the electronic configuration of FeN4 species and dramatically enhance catalytic activity toward ORR. The MXene with sulfur terminals induce the spin-state transition of FeN4 species and Fe 3d electron delocalization with d band center upshift, enabling the Fe(II) ions to bind oxygen in the end-on adsorption mode favorable to initiate the reduction of oxygen and boosting oxygen-containing groups adsorption on FeN4 species and ORR kinetics. The resulting FeN4-Ti3C2Sx exhibits comparable catalytic performance to those of commercial Pt-C. The developed wearable ZABs using FeN4-Ti3C2Sx also exhibit fast kinetics and excellent stability. This study confirms that regulation of the electronic structure of active species via coupling with their support can be a major contributor to enhance their catalytic activity.

Surface-enhanced emission from single semiconductor nanoribbons.

Emission enhancement from single semiconductor CdSe nanoribbons by introduction of surface plasmon polaritons (SPPs) via Au contacts is studied. Scanning confocal microscopy is employed to investigate the emission enhancement behavior via photoluminescence measurements. Large enhancement factors of 77-130 at a peak emission of CdSe of ∼710 nm are obtained, which are ascribed to the gain-assisted propagation of the short-range mode of SPPs. Our findings open the exciting possibilities for high-efficiency SPP-enhanced light-emitting devices based on luminous bodies with finite lateral dimensions.

Two-dimensional van der Waals heterostructures (vdWHs) with band alignment transformation in multi-functional devices.

Two-dimensional van der Waals heterostructures (vdWHs) with tunable band alignment have the potential to be benignant in the development of minimal multi-functional and controllable electronics, but they have received little attention thus far. It is crucial to characterize and control the band alignment in semiconducting vdWHs, which determines the electronic and optoelectronic properties. The future success of optoelectronic devices will require improved electronic property control techniques, such as using an external electric field or strain engineering, to change the electronic structures directly. Herein, we review heterostructures fabricated as transition metal dichalcogenides (TMDCs) as one of their constituent monolayers with other notable 2D materials that can transfer from type-II to type-III (type-III > type-II) band alignment when a biaxial strain or electric field is applied.

Violet-blue LEDs based on p-GaN/n-ZnO nanorods and their stability.

In this paper, we report a fabrication, characterization and stability study of p-GaN/n-ZnO nanorod heterojunction light-emitting devices (LEDs). The LEDs were assembled from arrays of n-ZnO vertical nanorods epitaxially grown on p-GaN. LEDs showed bright electroluminescence in blue (440 nm), although weaker violet (372 nm) and green-yellow (550 nm) spectral components were also observed. The device characteristics are generally stable and reproducible. The LEDs have a low turn-on voltage (∼5 V). The electroluminescence (EL) is intense enough to be noticed by the naked eye, at an injection current as low as ∼ 40 µA (2.1 × 10(-2) A cm(-2) at 7 V bias). Analysis of the materials, electrical and EL investigations point to the role of a high quality of p-n nano-heterojunction which facilitates a large rectification ratio (320) and a stable reverse current of 2.8 µA (1.4 × 10(-3) A cm(-2) at 5 V). Stability of EL characteristics was investigated in detail. EL intensity showed systematic degradation over a short duration when the LED was bias-stressed at 30 V. At smaller bias (<20 V) LEDs tend to show a stable and repeatable EL characteristic. Thus a simple low temperature solution growth method was successfully exploited to realize nanorod/film heterojunction LED devices with predictable characteristics.

Development of a sustainable photocatalytic process for air purification.

Nowadays, air pollution has become a global menace being responsible of a significant increase on the morbidity and mortality of human beings. In view of this, sustainable and efficient technologies for air purification are being sought. Air purification by photocatalytic treatment has received a lot of attention due to the unspecific and high oxidation capacity of the catalyst; however still some variables must be optimized to assure practical applications. In this work, visible light active TiO2-Cu2+@perlite and Ag@TiO2-Cu2+/perlite supported materials were fabricated. TiO2-Cu2+ (2 at. %) were synthesized using a sol-gel procedure followed of the impregnation of the support by immersion. For Ag@TiO2-Cu2+, silver deposition was conducted by chemical reduction using sodium citrate and sodium borohydride. The materials (powders and supported materials) were characterized by Scanning Electron Microscopy (SEM) to demonstrate their small size and adherence to the substrate. A prototype of a photocatalytic air purifier was built. The efficacy of the prototype was evaluated for the disinfection of indoor air (dentistry clinics). The photo-catalyst was activated using visible and UVA low-cost high-energy LEDs. The antibacterial activity of the air filter was evaluated. Ag@TiO2-Cu2+ exerts better air disinfection activity at lower doses in comparison to TiO2-Cu2+. Bacterial growth inhibitions up to 99% were achieved for both, Gram-negative and Gram-positive bacteria. The incorporation of Ag and Cu to TiO2 improves the antibacterial activity of the materials due to enhanced photocatalytic activity and the synergic activity of TiO2 and dopant elements (Ag, Cu) to inhibit microorganism's growth.

Hydrogen-Free and Dendrite-Free All-Solid-State Zn-Ion Batteries.

An ionic-liquid-based Zn salt electrolyte is demonstrated to be an effective route to solve both the side-reaction of the hydrogen evolution reaction (HER) and Zn-dendrite growth in Zn-ion batteries. The developed electrolyte enables hydrogen-free, dendrite-free Zn plating/stripping over 1500 h cycle (3000 cycles) at 2 mA cm-2 with nearly 100% coulombic efficiency. Meanwhile, the oxygen-induced corrosion and passivation are also effectively suppressed. These features bring Zn-ion batteries an unprecedented long lifespan over 40 000 cycles at 4 A g-1 and high voltage of 2.05 V with a cobalt hexacyanoferrate cathode. Furthermore, a 28.6 µm thick solid polymer electrolyte of a poly(vinylidene fluoride-hexafluoropropylene) film filled with poly(ethylene oxide)/ionic-liquid-based Zn salt is constructed to build an all-solid-state Zn-ion battery. The all-solid-state Zn-ion batteries show excellent cycling performance of 30 000 cycles at 2 A g-1 at room temperature and withstand high temperature up to 70 °C, low temperature to -20 °C, as well as abuse test of bending deformation up to 150° for 100 cycles and eight times cutting. This is the first demonstration of an all-solid-state Zn-ion battery based on a newly developed electrolyte, which meanwhile solves the deep-seated hydrogen evolution and dendrite growth problem in traditional Zn-ion batteries.

A generalized Stark effect electromodulation model for extracting excitonic properties in organic semiconductors.

Electromodulation (EM) spectroscopy, a powerful technique to monitor the changes in polarizability p and dipole moment u of materials upon photo-excitation, can bring direct insight into the excitonic properties of materials. However, extracting Δp and Δu from the electromodulation spectrum relies on fitting with optical absorption of the materials where optical effect in different device geometries might introduce large variation in the extracted values. Here, we demonstrate a systematic electromodulation study with various fitting approaches in both commonly adopted reflection and transmission device architectures. Strikingly, we have found that the previously ascribed continuum state threshold from the deviation between the measured and fitting results is questionable. Such deviation is found to be caused by the overlooked optical interference and electrorefraction effect. A generalized electromodulation model is proposed to incorporate the two effects, and the extracted Δp and Δu have excellent consistency in both reflection and transmission modes in all organic film thicknesses.

Enhanced electrochemical performance of lithium ion batteries using Sb2S3 nanorods wrapped in graphene nanosheets as anode materials.

Antimony sulfide can be used as a promising anode material for lithium ion batteries due to its high theoretical specific capacity derived from sequential conversion and alloying lithium insertion reactions. However, the volume variation during the lithiation/delithiation process leads to capacity fading and cyclic instability. We report a facile, one-pot hydrothermal strategy to prepare Sb2S3 nanorods wrapped in graphene sheets that are promising anode materials for lithium ion batteries. The graphene sheets serve a dual function: as heterogeneous nucleation centers in the formation process of Sb2S3 nanorods, and as a structural buffer to accommodate the volume variation during the cycling process. The resulting composites exhibit excellent electrochemical performance with a highly reversible specific capacity of ∼910 mA h g-1, cycling at 100 mA g-1, as well as good rate capability and cyclic stability derived from their unique structural features.

Hierarchical self-assembled Bi2S3 hollow nanotubes coated with sulfur-doped amorphous carbon as advanced anode materials for lithium ion batteries.

Bismuth sulfide (Bi2S3) is considered as a promising anode material for lithium ion batteries (LIBs) owing to its high theoretical specific capacity and intriguing reaction mechanism. However, capacity fading and cycling instability due to volume variation during the lithiation/delithiation process still remain a great challenge. Herein, we proposed a simple glucose assisted hydrothermal strategy and followed a post-treatment process to prepare hierarchical sulfur-doped carbon Bi2S3 (Bi2S3@SC) hollow nanotubes that self-assembled into sulfur-doped amorphous carbon coated Bi2S3 nanocrystals as building blocks. Glucose plays a decisive role in the formation process of Bi2S3 nanocrystals and subsequent self-assembly, forming Bi2S3@SC hollow nanotubes. The polysaccharide shell formed on the surface of Bi2S3 nanocrystals during the hydrothermal process was transformed into the sulphur-doped amorphous carbon layer after the post-treatment process. Electrochemical tests reveal that the resulting composites exhibit excellent electrochemical performance with a highly reversible cycling capacity of ∼950 mA h g-1 at a current density of 100 mA g-1, as well as a good rate capability and significantly enhanced cycling stability derived from their unique structural features, thus demonstrating the potential of Bi2S3@SC hollow nanotubes as high performance anode materials for LIBs. The analysis of electrochemical kinetics confirmed that the pseudocapacitive behavior dominates the overall storage process of Bi2S3@SC hollow nanotubes.

Flexible Waterproof Rechargeable Hybrid Zinc Batteries Initiated by Multifunctional Oxygen Vacancies-Rich Cobalt Oxide.

Although both are based on Zn, Zn-air batteries and Zn-ion batteries are good at energy density and power density, respectively. Here, we adopted Ar-plasma to engrave a cobalt oxide with abundant oxygen vacancies (denoted as Co3O4- x). The introduction of oxygen vacancies to cobalt oxide not only promotes its reversible Co-O ↔ Co-O-OH redox reaction but also leads to good oxygen reduction reaction and oxygen evolution (ORR/OER) performance (a half-wave potential of 0.84 V, four-electron transfer process for ORR, and 330 mV overpotential, 58 mV·dec-1 Tafel slope for OER). We then constructed a battery system based on both Zn-Co3O4- x and Zn-air electrochemical reactions. The hybrid battery reveals both a high-power density of 3200 W·kg-1 and high-energy density of 1060 Wh·kg-1. Furthermore, the developed flexible solid-state hybrid batterydemonstrates good waterproof and washable ability (99.2% capacity retention of after 20 h water soaking test and 93.2% capacity retention after 1 h washing test). Interestingly, the fabricated flexible battery can work under water, and after the power is exhausted, the battery can automatically recover electricity output as long as it is exposed to air. The developed device is suitable for wearable applications considering its electrochemical performances, great environmental adaptation, and "air recoverability". In addition, this study underscores the approach to develop hybrid energy-storage technologies through modification of electrode materials.

Characterization of Low-Frequency Excess Noise in CH3NH3PbI3-Based Solar Cells Grown by Solution and Hybrid Chemical Vapor Deposition Techniques.

In this study, detailed investigations of low-frequency noise (LFN) characteristics of hybrid chemical vapor deposition (HCVD)- and solution-grown CH3NH3PbI3 (MAPI) solar cells are reported. It has been shown that LFN is a ubiquitous phenomenon observed in all semiconductor devices. It is the smallest signal that can be measured from the device; hence, systematic characterization of the LFN properties can be utilized as a highly sensitive nondestructive tool for the characterization of material defects in the device. It has been demonstrated that the noise power spectral densities of the devices are critically dependent on the parameters of the fabrication process, including the growth ambient of the perovskite layer and the incorporation of the mesoscopic structures in the devices. Our experimental results indicated that the LFN arises from a thermally activated trapping and detrapping process, resulting in the corresponding fluctuations in the conductance of the device. The results show that the presence of oxygen in the growth ambient of the HCVD process and the inclusion of an mp-TiO2 layer in the device structure are two important factors contributing to the substantial reduction in the density of the localized states in the MAPI devices. Furthermore, the lifetimes of the MAPI perovskite-based solar cells are strongly dependent on the material defect concentration. The degradation process is substantially more rapid for the devices with higher initial defect density compared to the devices prepared under optimized conditions and structure that exhibit substantially lower initial trap density.