Search

Nanomaterials with intrinsic enzyme‐like properties, termed nanozymes, have attracted significant interest, although limited information is available on their biological characteristics in cells or in vivo. Here, it is shown that nanomaterials with peroxidase‐like activity trigger a novel form of cell death through an ATP‐citrate lyase (ACLY)‐dependent rat sarcoma viral oncogene (RAS) signaling mechanism. The peroxidase nanozyme‐induced cell lethality, which is termed as nanoptosis, is morphologically and biochemically distinct from the currently well‐defined apoptosis, necrosis, autophagy, pyroptosis, and ferroptosis. It is revealed that nanoptosis is typically characterized by the massive accumulation of cellular vesicles, swelling mitochondria, and distinct chromatin condensation and margination. Using RNA sequencing and protein quantitative mass spectrometry, an ACLY‐dependent RAS signaling pathway is identified that mainly mediates this nanozyme lethality process, and it is observed that RAS‐knockout cells are highly resistant to nanoptosis. Finally, it is demonstrated that this newly discovered nanozyme lethality can be used as an effective therapeutic strategy for inhibiting tumor growth in vivo. [ABSTRACT FROM AUTHOR]

The proposal of pseudocapacitive materials breaks the barriers between batteries and capacitors, allowing for the possible achievement of a balanced energy-power performance. However, the limited reserve of lithium restricts the practical applications of pseudocapacitive materials in lithium-based systems, whereas sodium resources are abundant with the similar properties to lithium, but there is a lack of suitable pseudocapacitive materials for sodium-based systems. The exploitation of pseudocapacitive materials for Na+ storage is urgent. This study, for the first time, reports a sonochemical approach, involving intercalation and ultrasonic exfoliation processes, to prepare composite K2Mo4O13/α-MoO3 (i.e., KMO) nanorods, and the possible applications of the KMO nanorods in Li+/Na+ pseudocapacitance were evaluated. The as-synthesized KMO possessed a uniform rod-like morphology formed by assembling nanoneedles (or nanobelts) with a large apparent aspect ratio of more than 10. Both in lithium ion batteries (LIBs) and sodium ion batteries (SIBs), the KMO nanorods exhibited efficient pseudocapacitance, which was not observed in the pristine MoO3–Na system. In SIBs, the as-synthesized KMO delivered a capacity of 895 mA h g−1 at 0.02 A g−1, which was much higher than that of the pristine MoO3–Na system. Moreover, it was found that the b values of KMO (i = avb, current i and scan rate v in the CV curves) were over 0.9 at potentials ranging from 1 V to 2 V in SIBs, indicating an obvious pseudocapacitive process. Benefiting from the layered K2Mo4O13 nanorods built with edge-shared distorted MoO6 octahedra, the Na+ ions with a larger size could be intercalated into the spaces between the double MoO6 plates. This sonochemical approach based on the intercalation and exfoliation chemistry opened a new path to prepare molybdenum-based nanostructures for superior Li+/Na+ pseudocapacitance applications on a large scale in a low-carbon and environment-friendly manner. [ABSTRACT FROM AUTHOR]

A novel efficient way to realize high performance TiO2 self-powered UV photodetectors (PDs) with enhanced responsivity is proposed in this work. By constructing asymmetric electrodes consisting of a commercial mixed silver paste and two different forms of Ag nanostructures (nanofilms and nanowires) on the active layer of TiO2, respectively. Both PD devices exhibited attractive photovoltaic characteristics in a self-powered mode (at 0 V bias). Interestingly, the responsivity of the TiO2 UV PDs is found to be enhanced by 9 times at the wavelength of 350 nm without any power supply when the configuration of the Ag nanostructure electrode was changed from nanofilms to transparent nanowires. The enhanced photoelectric conversion efficiency is mainly attributed to a modified Schottky barrier through reducing hole traps and a higher light absorptivity through using a transparent electrode according to the experimental results and physical models based on the energy band theory. In addition, TiO2 UV PDs with a Ag nanowire electrode also exhibited excellent photoelectric properties in terms of a high linear dynamic range of 103.7 dB, a fast response speed (rise time of 2 ms and fall time of 41 ms), and excellent stability. The design solutions proposed here may provide additional opportunities for further development of Schottky junction-based self-powered UV PDs with high efficiencies. [ABSTRACT FROM AUTHOR]

Exploring anode materials with excellent rate performance and high initial coulombic efficiency (ICE) is crucial for lithium/sodium-ion batteries (LIBs/SIBs). However, it is still very challenging to achieve this goal in a cost-effective way, particularly for SIBs. Herein, graphite oxide, was treated in ammonia atmosphere for a balance between the oxygen- and nitrogen-contained functional groups and yielded nitrogen-doped expanded graphite oxide (NEGO). Electrochemical characterizations were systematically carried out in ether and ester-based electrolytes to shed light on the storage mechanism of NEGO in SIBs. The ICE of NEGO employed in ether-based electrolyte improves to 72.08% from that in ester-based electrolyte (24.73%). Moreover, the as-synthesized NEGO exhibits ∼125 mA h g−1 and ∼110 mA h g−1 capacities in ether and ester-based electrolytes, respectively, even under a record high current density (30 A g−1). Expanded surface area and nitrogen doping significantly increase the active sites and decrease the electrical resistivity from 140 Ω (EGO) to 40 Ω (NEGO) by removing excess oxygen. Moreover, small amounts of residual oxygen, particularly quinone and carboxyl, along with nitrogen occupied sites offer additional pseudocapacitance. Considering the advantages in scale-up and cost-effective production, NEGO is a promising low-cost anode material for SIBs. This study also provides strategies for the design of electrolyte for SIBs to realize practical applications in power-grid energy storage. [ABSTRACT FROM AUTHOR]

Abstract: Graphene nanodots (GNDs) are one of the most attractive graphene nanostructures due to their tunable optoelectronic properties. Fabricated by polystyrene‐nanosphere lithography, uniformly sized graphene nanodots array (GNDA) is constructed as an ultraviolet photodetector (PD) with ZnO nanofilm spin coated on it. The size of GNDA can be well controlled from 45 to 20 nm varying the etching time. It is revealed in the study that the photoelectric properties of ZnO/GNDA PD are highly GNDA size‐dependent. The highest responsivity (R) and external quantum efficiency of ZnO/GNDA (20 nm) PD are 22.55 mA W−1 and 9.32%, almost twofold of that of ZnO PD. Both ZnO/GNDA (20 nm) PD and ZnO/GNDA (30 nm) PD exhibit much faster response speed under on/off switching light and have shorter rise/decay time compared with ZnO PD. However, as the size of GNDA increase to 45 nm, the PD appears poor performance. The size‐dependent phenomenon can be explained by the energy band alignments in ZnO/GNDA hybrids. These efforts reveal the enhancement of GNDs on traditional photodetectors with tunable optoelectronic properties and hold great potential to pave a new way to explore the various remarkable photodetection performances by controlling the size of the nanostructures. [ABSTRACT FROM AUTHOR]

The design of nanostructure plays an important role in performance enhancement of low-dimensional optoelectronic devices. Herein, a novel photodetector (PD) based on electrospun SnO2 nanofibers with Ω-shaped ZnO shell (SnO2@ZnO) is fabricated. With 87.4% transmittance at 550 nm, SnO2@ZnO PD exhibits a high photo-to-dark current ratio up to 104 at around 280 nm. Owing to the additional Ω-shaped ZnO shell, SnO2@ZnO PD possesses a responsivity of nearly 100 A W−1 under 5 V bias and the illumination of 250 nm light, which is 30-time enhancement of pristine SnO2 PD. The enhancement is mainly attributed to type-II energy band structure. Furthermore, by changing the direction of incident light, SnO2@ZnO PD has a high UV selectivity with an UV-vis rejection ratio ( R250 nm/ R400 nm) as much as 2.0 × 103 at 5 V bias under back illumination, which is fourfold higher than that under face illumination. The UV selectivity improvement may be attributed to light confinement in the Ω-shaped structure. With both theoretical simulations and experimental comparisons, it is demonstrated that the unique compact Ω-shaped nanostructure does contribute to photon trapping and gaining process, especially in back-illumination configuration. The approach can be easily extended to other materials, preparing novel building blocks for optoelectronic devices. [ABSTRACT FROM AUTHOR]

Due to the low density of nanostructured materials, it is still a big challenge to realize high volumetric performance instead of high specific gravimetric capacity with many state-of-the-art electrodes for compact electrochemical energy storage. Moreover, developing high-performance flexible and binder-free electrode materials is also crucial for their future applications in diverse fields, such as portable electronics and wearable devices. In this work, we designed and synthesized a Ni3V2O8/carbon cloth (CC) hierarchical structure as a flexible anode for sodium-ion batteries. Morphology-controllable growth of different Ni3V2O8/CC hierarchical structures is achieved by optimizing the synthesis parameters (e.g. the growth temperatures). The high mass loading (4 mg cm−2), ultra-high areal specific capacity (2.6 mA h cm−2 at a current density of 500 mA g−1), no addition of binders or other additives and good flexibility facilitate their application in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Intrinsically p-type conductivity and a wide bandgap of ≈3.6 V endow inorganic delafossite CuGaO2 with great promise for fabricating high-performance UV photodetectors. Nevertheless, CuGaO2-based optoelectronic devices hindered because the intrinsic direct transitions are symmetry forbidden in CuGaO2. This study reports a large-area synthesis of 'CuGaO2 nanoplate/ZnS microsphere' heterostructure arrays using a facile solution-based strategy associated with an oil/water interfacial self-assembly approach. It is found that a large number of ZnS microspheres with a polycrystalline structure grow on the top surface of CuGaO2 hexagonal platelets through Ostwald ripening mechanism, forming high-density p-n heterojunctions. A parabolic dependence between the size of ZnS microsphere and the growth time is confirmed in this growth. The UV light adsorption of the heterostructure CuGaO2/ZnS thin film is two times higher than that of the pristine CuGaO2 thin film. Furthermore, the as-designed 'CuGaO2 nanoplate/ZnS microsphere' heterostructure arrays exhibit enhanced photoresponse properties. This work offers a new insight into the rational design of optoelectronic devices from the synergetic effect of p-type 2D nanoplates as well as n-type nanostructures such as ZnS, ZnO, CdS, and CdO. [ABSTRACT FROM AUTHOR]

Hierarchical In2O3@WO3 nanocomposites, consisting of discrete In2O3 nanoparticles (NPs) on single-crystal WO3 nanoplates, were synthesized via a novel microwave-assisted growth of In2O3 NPs on the surfaces of WO3 nanoplates that were derived through an intercalation and topochemical-conversion route. The techniques of XRD, SEM, TEM and XPS were used to characterize the samples obtained. The gas-sensing properties of In2O3@WO3 nanocomposites, together with WO3 nanoplates and In2O3 nanoparticles, were comparatively investigated using inorganic gases and organic vapors as the target substances, with an emphasis on H2S-sensing performance under low concentrations (0.5–10 ppm) at 100–250 °C. The results show that the In2O3 NPs with a size range of 12–20 nm are uniformly anchored on the surfaces of the WO3 nanoplates. The amounts of the In2O3 NPs can be controlled by changing the In3+ concentrations in their growth precursors. The In2O3@WO3 (In/W = 0.8) sample has highest H2S-sensing performance operating at 150 °C; its response to 10 ppm H2S is as high as 143, 4 times higher than that of WO3 nanoplates and 13 times that of In2O3 nanocrystals. However, the responses of the In2O3@WO3 sensors are less than 13 upon exposure to 100 ppm of CO, SO2, H2, CH4 and organic vapors, operating at 100–150 °C. The improvement in response and selectivity of the In2O3@WO3 sensors upon exposure to H2S molecules can be attributed to the synergistic effect of In2O3 NPs and WO3 nanoplates, hierarchical microstructures and multifunctional interfaces. [ABSTRACT FROM AUTHOR]

Metal sulfides are a class of promising anodes for sodium‐ion batteries with high theoretical capacities. However, the properties of intrinsic metal sulfide anodes usually decay rapidly at initial cycling of batteries. Previously, it was believed that the low conductivity and volume expansion of metal sulfides lead to the poor performance. Here, using in situ batteries followed by the assistance of spectral analysis, it is shown that the polysulfide shuttling effect is one of the crucial factors for the degradation of metal sulfide anodes beyond traditional consensus of low conductivity and volume expansion. Furthermore, a novel strategy by controlling the dissolution of sodium polysulfides in selected electrolyte is proposed to enable intrinsic metal sulfides to work stably in polysulfide‐insoluble fluoroethylene carbonate electrolyte, which would decay fast in polysulfide‐soluble propylene carbonate electrolyte. This work has deepened the understanding of electrochemical reaction mechanisms of metal sulfide anodes and expanded the strategies to optimize the electrochemical performance of metal sulfides anodes. [ABSTRACT FROM AUTHOR]

An cross‐bar structure is employed to design a transparent p‐n junction‐based photodetector. The device consisting of aligned n‐SnO2 and p‐NiO nanofibers is prepared via a mature electrospinning process that is suitable for commercial applications. It exhibits a high detectivity of 2.33 × 1013 Jones under 250 nm illumination at −5 V, outperforming most state‐of‐art SnO2‐based UV photodetectors. It is also endowed with a self‐powered feature due to a photovoltaic effect from the p‐n junction, resulting in a photocurrent of 10−10 A, responsivity of 30.29 mA W−1 at 0 V bias, and detectivity of 2.24 × 1011 Jones at 0.05 V bias. Moreover, the device is highly transparent (over 90% toward visible light) due to the wide band gap of photoactive materials and well‐designed cross‐bar fiber structure. Additionally, an n‐SnO2‐p‐ZnO:Ag (Ag doped ZnO) self‐powered UV photodetector is fabricated that shows good performance and give another example of the use of the cross‐bar structure. [ABSTRACT FROM AUTHOR]

Transparent ultraviolet (UV) photodetectors are an essential component of next‐generation "see‐through" electronics. However, the current photodetectors often suffer from relatively slow response speeds and high driving voltages. Here, all‐solution‐processed UV photodetectors are reported that are facilely prepared from environmentally friendly and abundant materials. The UV photodetectors are composed of a titanium dioxide thin film as the photosensitive layer sandwiched between two different transparent electrodes to form asymmetric Schottky junctions. The photodetector with high optical transparency can operate at zero bias because of spontaneous separation of photogenerated electron–hole pairs by the built‐in electric field. The resulting self‐powered photodetector displays high sensitivity to broadband UV light (200–400 nm). In particular, an ultrafast response speed up to 44 ns is obtained, representing a significant improvement over those of the conventional transparent photodetectors. Moreover, the photodetector has been successfully applied, for the first time, in a UV communication system as the self‐powered signal receiver. This work uniquely combines the features of high optical transparency and self‐power ability into UV photodetectors and would enable a broad range of optoelectronic applications. [ABSTRACT FROM AUTHOR]

Sodium-ion capacitors (NICs) are considered an important candidate for large-scale energy storage in virtue of their superior energy–power properties, as well as availability of rich Na+ reserves. To fabricate high-performance NIC electrode material, a hydrothermal method was proposed to synthesize sulfur-doped reduced graphene oxide (SG), which exhibited unique layered structures and showed excellent electrochemical properties with 116 F/g capacitance at 1 A/g as the cathode of NICs from 1.6 V to 4.2 V. At the power–energy density over 5000 W/kg, the SG demonstrated over 100 Wh/kg energy density after 3500 cycles, which indicated its efficient durability and superior power–energy properties. The addition of a sulfur source in the hydrothermal process led to the higher specific surface area and more abundant micropores of SG when compared with those of reduced graphene oxide (rGO), thus SG exhibited much better electrochemical properties than those shown by rGO. Partially substituting surface oxygen-containing groups of rGO with sulfur-containing groups also facilitated the enhanced sodium-ion storage ability of SG by introducing sufficient pseudocapacitance. [ABSTRACT FROM AUTHOR]

[Display omitted] • One-to-one butted Ni 3 Fe−Fe 2 VO 4 heterostructure shows abundant heterointerface. • Close contact between two active sites realize the in-situ adsorption and catalysis of LiPSs. • Electron redistribution across the heterointerface enhances chemisorption and catalytic ability. • The Li − S battery suffers a capacity decay rate of 0.038% at low E/S ratio (5 μL mg−1). The shuttling effect of lithium polysulfides (LiPSs) and the sluggish redox reaction of sulfur prevent the practical applications of lithium−sulfur (Li−S) batteries. Herein, a Janus Ni 3 Fe−Fe 2 VO 4 heterostructure with a one-to-one butted configuration on carbon black (Ni 3 Fe−Fe 2 VO 4 /CB) is elaborately designed to realize the in-situ adsorption and catalysis of LiPSs. The special heterostructure shows a high concentration heterointerface and similar exposed surface area by optimizing the distribution and proportion of two kinds of active sites. Moreover, the covalent connection of Ni 3 Fe and Fe 2 VO 4 phases produces electron redistribution in the heterostructure which further increases the chemisorption and catalytic ability of Fe 2 VO 4 and Ni 3 Fe, respectively. It benefits the more efficient conversion for LiPSs. Battery with Ni 3 Fe−Fe 2 VO 4 /CB decorated separators remains 983.6 mAh g−1 after 500cycles at 0.2C, corresponding capacity decay rate of 0.028% per cycle, and high-rate capability of 877.5 mAh/g at 2.0C, which is 62.7% higher than battery with pristine polypropylene (PP) separators (539.5 mAh g−1). Even at the low E/S ratio (5 μL mg−1), it provides an excellent capacity decay rate of 0.038% per cycle over 500cycles, much lower than the pristine (0.109%). This work on heterostructure engineering offers an efficient spatial continuous reaction, which is valuable for integrating the adsorption and catalytic conversion processes for Li−S batteries. [ABSTRACT FROM AUTHOR]

Ultrasensitive pressure sensors are constructed with few-layer MoS 2 films. As-designed Fabry-Perot (F-P) sensors exhibit nearly synchronous pressure-deflection responses with a very high sensitivity (89.3 nm Pa -1 ), which is three orders of magnitude higher than those of conventional diaphragm materials (e.g., silica, silver films). This kind of F-P sensor may open up new avenues for 2D materials in biomedical and environmental applications., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)