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Three-dimensional (3D) frameworks have received much attention as an effective modification strategy for next-generation high-energy–density lithium metal batteries. However, the top-growth mode of lithium (Li) on the 3D framework remains a tough challenge. To achieve a uniform bottom-up Li growth, a scheme involving Ag concentration gradient in 3D PVDF framework (C-Ag/PVDF) is proposed. Ag nanoparticles with a concentration gradient induce an interface activity gradient in the 3D framework, and this gradient feature is still maintained during the cycle. As a result, the C-Ag/PVDF framework delivers a long lifespan over 1800 h at a current density of 1 mA cm−2 with a capacity of 1 mAh cm−2, and shows an ultra-long life (>1300 h) even at a high current density of 4 mA cm−2 with a capacity of 4 mAh cm−2. The advantage of concentration gradient provides further insights into the optimal design of the 3D framework for stable Li metal anode.

Cobalt-free LiNiO2 cathode materials offer a higher energy density at a lower cost than high Co-containing cathode materials. However, Ni(OH)2 precursors for LiNiO2 cathodes are traditionally prepared by the coprecipitation method, which is expensive, complex, and time-consuming. Herein, we report a fast, facile, and inexpensive electrolysis process to prepare a Ni(OH)2 precursor, which was mixed with LiOH/LiNO3 salts to obtain a LiNiO2 cathode material. A combination of advanced characterization techniques revealed that the LiNiO2 cathode material prepared in this way exhibited an excellent layered structure with negligible Li/Ni site mixing and surface structural distortion. Electrochemical cycling of the LiNiO2 cathode material showed an initial discharge capacity of 235.2 mA h/g and a capacity retention of 80.2% after 100 cycles (at 1 C) between 2.75 and 4.3 V. The degradation of the cycling performance of the LiNiO2 cathode material was mainly attributed to the formation of a surface solid-electrolyte interface and a ∼5 nm rock salt-like structure, while the bulk structure of the cathode after cycling was generally stable.

A green and facile synthesis of anisotropic 3D architecture high-performance carbon catalyst has been a hot research topic. Herein, a facile and scalable strategy was developed to fabricate an N, S co-doped microcellular carbon from natural polymers of chitosan (N-source) and lignosulfonate (S-source), with the properties enhanced as a result of pre-cryocrushing of natural polymer-based carbon precursors. The as-prepared 3D architecture carbon is mechanically strong and contains cross-linked hierarchical porous micro-sheets and micro-channels. This N and S co-doped carbon, prepared from pre-cryocrushing of chitosan (60%) and lignosulfonate (40%) precursor (NSC/CC-C/L (60/40)), annealed at 900 °C shows unique structures, with significant defects, rough edges, rich micro/meso-pores, large surface area, N and S doping, and high pyridinic-N and thiophene-S contents. The NSC/CC-C/L (60/40)-900 sample exhibits superior performance with favorable kinetics, methanol resistance, and excellent durability as an ORR catalyst, all of which are much better than a commercial Pt/C and most reported metal-free catalysts. Impressively, the onset potential of the NSC/CC-C/L-900 sample reaches 1.08 V (vs. reversible hydrogen electrode) and the half-wave potential is 0.98 V, which are compared to 1.02 and 0.92 V for Pt/C.

Sn anode materials with high specific capacity are an appealing alternative to graphite for next-generation advanced lithium-ion batteries. However, poor electrochemical performance originating from fracture and pulverization due to the enormous volume changes during lithium alloying/dealloying hinders their commercial applications. Here, we propose the synthesis of a novel 3D structured Sn anode material by a facile method: heat treatment of nanosized SnO2 spheres in a tube furnace with a flowing mixed atmosphere of C2H2/Ar at 400 °C. After the heat treatment, the nanosized SnO2 spheres convert into pure Sn bulk material (~20 μm), which consists of Sn nanowires (~50 nm in diameter and several microns in length). This unique 3D structure with sufficient voids between the nanowires effectively mitigates the volume expansion of Sn bulk material and ensures good electrical contact between the anode material and conducting additives. As a consequence, the 3D structured Sn anode material exhibits a specific reversible capacity of ~600 mA h/g and no significant capacity degradation (compared with that of the 20th cycle) over 500 cycles at 0.2 C.

Herein, we have successfully synthesized phosphorus/nitrogen/silicon tri-elements compound phosphazene derivative hexa-[4-( N-(3-(triethoxysilyl)propyl)acetamide)phenoxy]cyclotriphosphazene (HNTPC) from hexachlorotriphosphazenitrile, methyl 4-hydroxybenzoate, and 3-triethoxysilylpropylamine, and it was used as an additive flame retardant in epoxy resin (EP). Then, the thermal stability and flame retardancy of the composite (HNTPC/EP) were tested. Thermogravimetric analysis showed that the presence of HNTPC made EP matrix decompose at a relatively low temperature, thus promoted the formation of a stable coke layer and protected the matrix from fire. Therefore, the amount of carbon residue was markedly increased at 800°C, indicating an outstanding condensed phase flame-retardant effect. Furthermore, various combustion test data manifested that the addition of HNTPC could significantly improve the flame-retardant performance of EP. In addition, the sample could pass the vertical burning tests (UL-94) V-1 grade when the addition amount was 10% and the limiting oxygen index value was 32.6%, the peak heat release rate and total heat release rate decreased by 40.0% and 21.5%, respectively. Besides, the results of scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy also showed that HNTPC can promote the formation of carbon layer and improved the flame-retardant property of EP. Finally, the condensed phase and gas phase synergistic flame-retardant mechanism of HNTPC was proposed.

The carbon-conducting additive-induced degradation of the cycling performance of lithium-ion batteries needs to be carefully controlled, particularly at a high operating voltage and elevated temperature. Herein, we report the investigation of surface coating with 2–3 nm of Al2O3, TiO2 and Ta2O5 oxides on Super P carbon black via atomic layer deposition. Detailed step potential tests revealed that after storage in EC/DMC electrolyte for 14 days at 55 °C, the stability of Ta2O5-coated Super P was the highest compared with those of Al2O3- and TiO2-coated counterparts. This result is attributed to Ta2O5 acting as a HF barrier, which mitigates the oxidation of electrolyte on the surface of Super P, as observed by XPS, thus showing less deposition of carbonate species. Further experiments showed that the surface of the Ta2O5 coating layer was stable, while the Al2O3 and TiO2 coating layers were completely dissolved in dilute HF after storage for 12 h Ta2O5-coated Super P was verified in a LiNi0.5Mn1.5O4 half-cell charged to 4.9 V at 55 °C. The results showed that with Ta2O5-coated Super P as the conducting additive, the half-cell exhibited an improved coulombic efficiency of 99.5%, compared with 98.3% for the pristine Super P.

Sodium-metal batteries with conventional organic liquid electrolytes have disadvantages including dendrite deposition and safety concern. In this work, we report a low-flammable electrolyte (NaPF6-...

In this paper, we report a facile method for the in situ deposition of a thin solid electrolyte layer on the surface of anode materials, which can significantly improve the rate capability and reduce the time for reaching capacity maximum. The thin solid electrolyte layer (∼8 nm) is formed by adding a small amount of LiNO3 into the anode materials; the added LiNO3 decomposes irreversibly into Li3N and LiNxOy on the surface of the anode materials during the first cycle, facilitating fast diffusion of lithium ions and limiting the formation of the surface electrolyte interface films. This is verified by adding LiNO3 into graphite half-cells which shows a fast activation process at high current density: in particular, the charge capacity reaches its maximum after only ∼30 and ∼40 cycles at 170 and 340 mA g−1, respectively, compared to ∼50 and ∼80 cycles for the graphite half-cell. Furthermore, the LiNO3 additive results in high capacity retention at high C-rates, with a value of 82.4% at 680 mA g−1, compared with 22.4% for the graphite half-cell. The facile and low-cost method reported here is expected to be readily applicable to other electrode materials for high-performance lithium-ion batteries.

Inspired by the hierarchical structure of natural nacre, a binary artificial nacre with excellent mechanical performance, tensile strength and toughness was successfully constructed based on water-soluble cellulose acetate (WSCA) and reduced graphene oxide (rGO). The tensile strength and toughness of the hybrid films were markedly improved by the introduction of rGO, and the tensile strength and toughness of the rGO/WSCA composite films reached 499.3 MPa and 9.6 MJ/m3 (rGO-WSCA-III), respectively, which are approximately 5.0 and 5.3 times that of natural nacre. In addition, the hybrid rGO/WSCA films showed better flame retardancy and stability in water, and high electrical conductivity. In this study, we provide a strategy to design and fabricate exceptionally strong and tough artificial nacre, which has potential application in tissue engineering and as a humidity sensor.

A new type of Pd@mSiO2 composite nanospheres with controlled pore structure, consisting of internal Pd cores and controlled mesoporous silica shells, has been prepared by a facile one-pot method. The thickness and pore size of the shell could be easily tuned by changing the amounts of TEOS and the hydrophobic block length, respectively, during synthesis. In this perspective, the effects of CTAB concentration, pH, and TEOS concentration on the monodisperse sphere morphology of Pd@mSiO2 nanoparticles (NPs) were investigated. In addition, a nucleation mechanism was proposed. Hydrogenation of nitrobenzene to aniline was used as a model reaction to discuss the effect of pore size on the transport rate of the reactants and the product selectivity in metal-catalyzed hydrogenation. The catalysts exhibited a high conversion rate and significantly enhanced stability, leading to a higher recyclability without loss of catalytic activity compared to conventional supported catalysts and commercial catalysts.

Membrane technology is one of the most promising technologies for wastewater remedy. However, it remains challenging to prepare high-performance membrane matrix for complex pollutants, e.g. containing both oil and organic dye. In this work, we facilely fabricate a cellulose-fiber-supported MOF photocatalytic membrane, namely Ag@AgCl@MIL-100(Fe)/CCF, which was prepared via carboxymethylation of cotton fabric (CCF) as scaffold and in-situ synthesis of MOF derivative as photocatalyst. The carboxymethylation significantly improves the hydrophilicity of cotton fabric and the deposition amount of MIL-100(Fe). The high hydrophilicity of modified CCF and porous MIL-100(Fe) further enable the membrane with an efficient adsorption capacity of dyes and underwater oleophobicity against oils. The photocatalysts Ag@AgCl nanoparticles anchored onto MIL-100(Fe) promote the photocatalytic activity. As a result, the membrane shows simultaneous high removal efficiency towards dyes (97.3 %) and oils (99.64 %). Additionally, thanks to the good photocatalytic activity against organic pollutants, the membrane exhibits excellent self-cleaning and a long-term reuse capacity.

Spinel cathode materials (e.g., LiMn2O4 and LiNi0.5Mn1.5O4) with strongly bonded surface coatings are desirable for delivering improved electrochemical performance in long-term cycling. Here, we report that the introduction of bridging ions such as Fe and Co, which can diffuse into both the spinel cathode materials and Li3PO4, the latter is found to cover the spinel surface in the form of dense and uniform particles (∼2-3 nm). Detailed structural analysis of the surface reveals that the bridging ions diffuse into the 16c site of the spinel structure to form ion-doped spinel cathode materials, which contribute to the formation of strong bonds between the surface and Li3PO4, possibly via spinel-(surface bridging ions)-Li3PO4 bonds. The critical role of the surface bridging ions is further investigated by heating the as-formed Li3PO4-coated spinel cathode materials (with bridging ions) to high temperatures, resulting in further diffusion of bringing ions from the surface to the interior of the spinel materials and consequently depletion of the surface spinel-(surface bridging ions)-Li3PO4 bonds. This leads to the gradual growth of surface Li3PO4 particles (∼20 nm) and the exposure of the spinel surface.

A new and environmental friendly route has been developed to hydrogenate α-pinene to cis-pinane. The α-pinene was hydrogenated using ruthenium (Ru) nanoparticles that were stabilized by modified carboxymethyl cellulose in aqueous medium. The conversion of α-pinene reached 96.6% and the selectivity of cis-pinane was 98.4%. Ru nanoparticles could be recycled 18 times. Ru nanoparticles and micelles were characterized by transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), dynamic light scattering (DLS), X-ray diffraction (XRD), and other detection techniques. Ru nanoparticles (3.2 nm) had a good stability and uniform distribution, the reaction was divided into micelles that appeared to act as “microreactors”, and the micelle size was increased in the absence of sodium carbonate. The good stability of the Ru nanoparticles could be attributed to electrostatic and steric stabilization.

High-voltage spinel LiNi0.5Mn1.5O4 cathode materials typically exhibit a perfect octahedral morphology; i.e., only the {111} planes are observed. However, a truncated octahedral morphology is sometimes observed with the appearance of both the {100} planes and the {111} planes. The underlying mechanism of this morphological transformation is unclear. CS corrected scanning transmission electron microscopy (STEM) techniques were used to study LiNi0.5Mn1.5O4 samples lifted by a focused ion beam (FIB) to determine the atomic-level crystal and electronic structures of the octahedral and truncated octahedral morphologies. STEM images directly show that the appearance of the {100} planes in the truncated octahedral particles of LiNi0.5Mn1.5O4 is closely associated with the atomic-level migration of Ni and Mn ions in the surface region. The STEM electron energy loss spectroscopy (EELS) confirms the presence of oxygen-deficient and Ni-rich areas, particularly in the region close to the newly formed {100} planes. Th...

Ni-doped spherical mesoporous carbon catalysts (Ni/C n ) were prepared via one-pot hydrothermal carbonization of microcrystalline cellulose (MCC) with nickel acetate as the Ni source. This exhibited a high conversion rate for p-nitrophenol (PNP) hydrogenation to p-aminophenol (PAP). The obtained catalysts contained 0.87–6.84 wt% nickel content that primarily consisted of metallic nickel, with a small amount of nickel oxide. The Ni additive could be beneficial in the formation of the mesoporous structure. The results showed that as the Ni content increased, the mesoporous percentage increased. The doped Ni was monodispersed particles added into the carbon skeleton with an average particle size of 23.6 nm. They were surrounded by ordered striped carbon that exhibited a graphite-like structure. The catalytic hydrogenation reaction took place at normal temperatures and pressure exhibited high catalytic activity. The degradation rate of PNP reached 99.7% when 0.30 g of the Ni/C0.2-900 catalysts was used for a reaction time of 40 min, with corresponding apparent rates constant of 1.68 × 10−3 S−1, apparent activation energy of only 43.25 kJ/mol.

Stabilization of the atomic-level surface structure of LiMn2O4 with Al3+ ions is shown to be significant in the improvement of cycling performance, particularly at a high temperature (55 °C) and high voltage (5.1 V). Detailed analysis by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy, etc. reveals that Al3+ ions diffuse into the spinel to form a layered Li(Alx,Mny)O2 structure in the outmost surface where Al3+ concentration is the highest. Other Al3+ ions diffuse into the 8a sites of spinel to form a (Mn3-xAlx)O4 structure and the 16d sites of spinel to form Li(Mn2-xAlx)O4. These complicated surface structures, in particular the layered Li(Alx,Mny)O2, are present at the surface throughout cycling and effectively stabilize the surface structure by preventing dissolution of Mn ions and mitigating cathode-electrolyte reactions. With the Al3+ ions surface modification, a stable cycle performance (∼78% capacity retention after 150 cycles) and high Coulombic efficiency (∼99%) are achieved at 55 °C. More surprisingly, the surface-stabilized LiMn2O4 can be cycled up to 5.1 V without significant degradation, in contrast to the fast capacity degradation found in the unmodified case. Our findings demonstrate the critical role of ions coated on the surface in modifying the structural evolution of the surface of spinel electrode particles and thus will stimulate future efforts to optimize the surface properties of battery electrodes.

Mixed silicon and carbon (Si–C) materials with high capacity are ideal candidates for the substitution of graphite or other carbon anodes in lithium-ion batteries. However, the low coulombic efficiency of the Si–C anode in the first cycle due to the formation of a solid electrolyte interphase and the consumption of active lithium have hindered its commercial applications. Here, we report using Li2S as a prelithiation material to compensate for the loss of active lithium in the first cycle and, consequently, to enhance the specific energy of lithium-ion batteries. The Si–C anode has an initial discharge specific capacity of ∼738 mA h g−1 and a charge specific capacity of ∼638 mA h g−1. The prelithiation material with a core–shell structure is prepared by mixing Li2S, Ketjenblack (KB) and poly(vinylpyrrolidone) (PVP) in anhydrous ethanol, which shows a high irreversible capacity of ∼1084 mA h g−1. The effect of the compensation of lost active lithium is verified via a LiFePO4 (Li2S)/Si–C full cell, which exhibits not only a high specific capacity but also a stable cycling performance. The specific energy of the LiFePO4 (Li2S)/Si–C full cell shows a remarkable increase compared to the LiFePO4/Si–C full cell, exhibiting ∼13.4%, ∼26.7%, ∼65.0% and ∼110.2% more specific energy after the 1st, 10th, 100th and 200th cycle, respectively.

The formation of Li dendrites is effectively inhibited by utilizing a small amount of polysulfide (1 to 2 mM Li2Sx, 2 ≤ x ≤ 8) in a conventional carbonate electrolyte to introduce a significant amount of polyethylene oxide (PEO)-like polymers into solid-electrolyte interphase (SEI) films. The polysulfide added likely acts as a catalyst rather than an additive, which is not consumed during repeated charging/discharging cycles. Thus the stability of Li-metal batteries during prolonged cycling is remarkably improved.

Lithium-ion batteries with graphite as the anode consume ∼10% of the active lithium from the cathode to form a solid electrolyte interphase layer during the first cycle, resulting in a reduced reversible capacity. Here, we report using Li2S as a cathode pre-lithiation material to compensate for the loss of active lithium and, consequently, enhance the specific energy of lithium-ion batteries. A Li2S material with a core-shell structure is prepared by mixing Li2S, Ketjenblack (KB) and poly(vinylpyrrolidone) (PVP) in anhydrous ethanol, and the material shows a specific charge capacity of ∼1053 mAh g−1 (631 mAh g−1 based on the total weight of cathode pre-lithiation materials, binders and conductive additives). The ability of this material to compensate for active lithium is investigated by coating a typical cathode LiFePO4 as an example, with the core-shell Li2S/KB/PVP via a simple and non-toxic coating method. Our results show that the LiFePO4 (Li2S)/graphite full cell exhibits a specific discharge capacity of 146.7 mAh g−1 in the first cycle, which is the same as the specific discharge capacity of the LiFePO4 half cell. XPS analysis reveals Li2S decomposes into lithium ions and sulfur with release of electrons in the first charge. Such a successful extraction of the active lithium from Li2S results in excellent cycling performance with increased specific energy.

Distorted surface regions (5–6 nm) with an unusual layered-like structure on LiMn2O4 cathode material were directly observed after it was cycled (3–4.9 V), indicating a possible spinel-to-layered structural transformation. Formation of these distorted regions severely degrades LiMn2O4 cathode capacity. As we attempt to get a better understanding of the exact crystal structure of the distorted regions, the structural transformation pathways and the origins of the distortion are made difficult by the regions’ nanoscopic size. Inspired by the reduction of Mn4+ to Mn3+ in surface electronic structures that might be associated with oxygen loss during cycling, we further investigated the atomic-level surface structure of LiMn2O4 by heat-treatments between 600 and 900 °C in various atmospheres, finding similar surface spinel-to-layered structural transformation only for LiMn2O4 heat-treated in argon atmosphere for a few minutes (or more). Controllable and measurable oxygen loss during heat-treatments result in M...

Carbon dots are a new and important form of zero-dimensional carbonaceous nanomaterials. In our present work, disperse water-soluble fluorescent carbon dots were prepared using coffee grounds as raw material by hydrothermal treatment. The as-prepared carbon dots exhibit an excitation-dependent and high photostable photoluminescence behavior which can be applied to Hela cell imaging. Notably, the fluorescence of the carbon dots can be quenched by Fe3+ ions, which can serve as a useful fluorescent probe for detecting Fe3+ ions.

Batteries with lithium metal anodes are promising because of lithium’s high energy density. However, the growth of Li dendrites on the surface of the Li electrode in a liquid electrolyte during cycling reduces the safety and cycle performance of batteries, hindering their commercial application. In this work, we observe for the first time a smooth and dendrite-free Li deposition with a vertically grown, self-aligned, and highly compact columnar structure formed during cycling in a mixed carbonate–ether electrolyte. The stable microsized (∼10 μm in diameter and ∼20 μm in length) Li deposits are aligned in arrays on the surface of the Li electrode. The columnar Li deposits still exhibit a dendrite-free morphology and a compact structure after 200 cycles at a current density of 1 mA/cm2 and a 1.5 mAh/cm2 cycling capacity in a mixed carbonate–ether electrolyte. This work shows an optimiztic outlook for Li batteries with liquid electrolytes.

We propose a resonant cavity enhanced (RCE) N-structure type-II superlattice (T2SL) mid-wavelength infrared (MWIR) photodetector which can be used for the detection of methane gas at 3.3 μm. The theoretical analysis of quantum efficiency (QE) shows that the peak QE can be enhanced from 0.45 to 0.80 at 3.3 μm after 12 period AlAs0.09Sb0.91/GaSb DBR is introduced to the N-structure T2SL detector and QE exhibits the narrow bandwidth characteristic near the target wavelength. By analyzing the refractive indices of different materials and the reflectance of different DBRs, we also discuss how to determine the component materials of quarter-wavelength DBR reflectors.

Detailed investigation of the influence of surface modification using a typical oxide (TiO2) on the electrochemical cycling performance of LiNi0.5Mn1.5O4 at room temperature (25 °C) and elevated temperature (55 °C) is reported. This spinel cathode material is commonly surface-modified with various metal oxides to improve its electrochemical cycling performance in lithium ion batteries. However, the underlying mechanisms of such a treatment, with respect to the surface crystal structure and chemistry evolution, have remained unclear. Bare-LiNi0.5Mn1.5O4 and TiO2-modified LiNi0.5Mn1.5O4 both show excellent cycling performance, i.e. almost no capacity retention and ∼99% coulombic efficiency for 150 cycles, at room temperature. However, at 55 °C the latter shows significantly better electrochemical cycling performance, with 93% capacity retention and ∼96% coulombic efficiency for 100 cycles, than the former with 70% capacity retention and ∼93% coulombic efficiency. Via advanced electron microscopy techniques, we observed that titanium ions migrated into the surface region of LiNi0.5Mn1.5O4 during the surface modification process at high temperature and reconstructed the (1–3 nm) surface spinel structure into a rocksalt-like structure and the subsurface (several nanometers) into a pseudo-rocksalt-like structure. The reconstruction of the surface and subsurface of the LiNi0.5Mn1.5O4 spinel cathode material mitigates not only the migration of Mn ions from the bulk into the electrolyte but also the formation of a solid state electrolyte interface, which plays a critical role in the improvement of electrochemical cycling performance at elevated temperatures.

The 〈 100 〉 crystal-oriented silicon micropillar array platforms were prepared by microfabrication processes for the purpose of electrolyte additive identification. The silicon micropillar array platform was used for the study of fluorinated vinyl carbonate (FEC), vinyl ethylene carbonate (VEC), ethylene sulfite (ES), and vinyl carbonate (VC) electrolyte additives in the LiPF6 dissolved in a mixture of ethylene carbonate and diethyl carbonate electrolyte system using charge/discharge cycles, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, and x-ray photoelectron spectroscopy. The results show that the silicon pillar morphology displays cross-shaped expansion after lithiation/delithiation, the inorganic lithium salt keeps the silicon pillar morphology intact, and the organic lithium salt content promotes a rougher silicon pillar surface. The presence of poly-(VC) components on the surface of FEC and VC electrodes allows the silicon pillar to accommodate greater volume expansion while remaining intact. This work provides a standard, fast, and effective test method for the performance analysis of electrolyte additives and provides guidance for the development of new electrolyte additives.

Nickel-rich layered LiNi0.8Co0.1Mn0.1O2 is a promising cathode material due to its high specific capacity. However, commercial application of this material is impeded by its rapid capacity degradation associated with structural instability. In this work, 0.5–2 mol% Nb5+ doped LiNi0.8Co0.1Mn0.1O2 cathode material is prepared by heat treatment of a mixture of stoichiometric amounts of nano-sized Nb2O5 powders, co-precipitated NixMn1-x(OH)2 precursors, and LiOH·H2O. The results show that Nb5+ doping significantly improves the cycling properties of LiNi0.8Co0.1Mn0.1O2 cathode material and that the optimal Nb5+ content in the structure is 1 mol%. Under a voltage range of 2.75–4.3 V, 1 mol% Nb5+ doped LiNi0.8Co0.1Mn0.1O2 cathode material shows an initial discharge capacity of 180.2 mAh/g at 0.1C, with a capacity retention of 96.9% for subsequent 300 cycles at 1C at room temperature. In contrast, bare LiNi0.8Co0.1Mn0.1O2 shows a capacity retention of only ~79.8% under the same conditions, with an initial specific discharge capacity of 184.9 mAh/g. The improvement in cycling performance is attributed to stabilization of the layered structure by Nb5+, mitigated migration of Ni2+ to the Li layer, improved lithium diffusion kinetics and reduced lattice expansion/shrinkage during cycling. Stabilization of the layered structure by Nb5+ doping is further reflected by the observation of fewer cracks in cathode electrodes after prolonged cycling.

We propose a high performance N-structure type-II superlattice (T2SL) photodetector for long wavelength infrared (LWIR) applications. Theoretical study on the electrical and optical properties of the N-structure T2SL LWIR detector with different carrier concentration and different thicknesses in the p-region is carried out. We obtain the relationship of material parameters and performance parameters. With the increasing of the thickness of p-region, quantum efficiency ( QE ) gradually improves. In contrast, zero-bias resistance area ( R 0 A ) product decreases. QE will significantly decreases when the carrier concentration of p-region is too high, while R 0 A first increases, then decreases. The results show that the performance of the N-structure T2SL LWIR detector can be state of the art by optimizing the carrier concentration and material thickness during the structure growth and device fabrication.

We experimentally demonstrate a monolithic single polarization nonlinear chirped pulse amplification (CPA) system producing high-average-power femtosecond pulses operating at 1.06 μm. Thanks to the fiber-based components and standard fiber splicing techniques, the system is nearly fully fiberized, except for the bulk grating pulse compressor. The main fiber amplifier delivers chirped picosecond pulses with average power of 193 W, repetition rate of 80 MHz, and duration of 209 ps. The pulse compressor is designed using high line density transmission gratings to keep small grating separation for the consideration of compactness and simplicity. After pulse compression, femtosecond pulses with average power of 119 W, duration of 352 fs, and peak power of 4.2 MW are obtained. The compression efficiency is 61.5%, limited by the diffraction efficiency of transmission gratings. Even so, to our knowledge, this is the highest average power ever reported in fiber CPA systems with a fiber-based stretcher. The mismatched third-order dispersion between fiber stretcher and bulk optical grating compressor is successfully compensated via optimization of the total nonlinear phase shift in the fiber amplifier chain.

Electrolytes compatible with lithium metal (Li) anode and cathode materials are regarded as one of the most crucial components toward the practical deployment of rechargeable lithium metal batteries (RLMBs). Herein, we report a highly salt-concentrated electrolyte (SCE) comprising lithium bis(fluorosulfonyl)imide (LiFSI) and 1,3-dioxolane (DOL)-based ether solvents for stable cycling of 4-V-class rechargeable Li cells. The selective addition of 1,8-diazabicyclo(5.4.0)undec‑7-ene (DBU) is capable of suppressing the ring-opening polymerization of DOL. The resulting LiFSI-DOL-based SCE shows excellent chemical stability (150 days), good anodic stability (ca. 5.0 V vs. Li/Li+), and decent ionic conductivity (1.3 mS cm−1) at room temperature. Using the LiFSI-DOL-based SCE, the Li || Cu cells exhibit dendrite-free Li deposition/dissolution processes with high Coulombic efficiencies (> 99%), and the Li || LiNi1/3Mn1/3Co1/3O2 cell shows good capacity retention (81% after 400 cycles). These results strongly suggest the feasibility of the LiFSI-DOL-based SCE as electrolyte for 4-V-class RLMBs.

The high-voltage spinel LiNi0.5Mn1.5O4 cathode material suffers from the rapid degradation of electrochemical cycling performance at elevated temperatures, which prevents its successful commercialization. Herein, we show that coating the surface of this material with Ta2O5, which has high resistance against hydrofluoric acid (HF) attack, is an effective way to improve its electrochemical cycling performance. A Ta2O5-coated LiNi0.5Mn1.5O4 half-cell shows a capacity retention of ∼93% and a Coulombic efficiency of ∼98% after 100 cycles at 55 °C, compared to the corresponding values of ∼76% and ∼95% measured for the bare LiNi0.5Mn1.5O4 half-cell. The detailed structural analysis of the Ta2O5-coated LiNi0.5Mn1.5O4 shows that a small amount of Ta5+ ions diffuse into the 16c site on the cathode surface during the coating process, as directly observed by Cs corrected scanning transmission electron microscopy. The modification of the LiNi0.5Mn1.5O4 surface with Ta5+, together with the residual Ta2O5 coating, stabi...

Herein, an imprinted electrochemical sensor based on graphene-Au nanoparticles incorporated with molecularly imprinted polymer (MIP) was fabricated for determination of 4-nonylphenol (4-NP). Grafted MIP electropolymerized on nanoscale multilayer films electrode was achieved using 4-NP as a template and P-aminothiophenol as a functional monomer. The electrochemical properties of the MIP nanoscale multilayer membrances were characterized and measured by cyclic voltammetry and differential pulse voltammetry techniques; using ferrocyanide/ferricyanide-redox marker. Several important parameters were optimized and investigated to improve the performance of the sensor. Under the optimized conditions, the developed sensor showed an excellent linear response over the concentration ranges of 50–500 ng mL−1 (4-NP) with a detection limit of 0.01 ng mL−1(S/N = 3). The developed sensor showed a good selective recognition of 4-NP compared with structural analogue, exhibited a good reproducibility and accuracy with long-term stability. At last, the feasibility of the proposed methodology was successfully applied fordetection of 4-NP in milk and its packaging materials.

As a lignocellulosic material, wastepaper is a potential material for ethanol production. However, little research on the enzymatic hydrolysis of wastepaper pulp has been conducted. In this study, the enzymatic hydrolysis of different waste pulp fractions (R80 represents greater than 80-mesh wastepaper pulp, R80-180 represents the range of 80- to 180-mesh wastepaper pulp, and R180 represents smaller than 180-mesh waste paper pulp) were carried out at 50 °C, pH 4.8, for 96 h, with a substrate concentration of 5% (w/v) and cellulase loading of 18 FPU/g cellulose. In terms of the specific surface area, fiber structure, and surface morphology, R80-180 had the highest affinity to cellulase and therefore the highest glucose yield of 80.33%. R180 had the lowest glucose yield (55.36%) because of its high ash content (21.36%), which reduced the adsorption of cellulase to cellulose. The enzymatic hydrolysis of R80 mixed with R80 or R80-180 was also studied. Results indicated that adding R80-180 increased the glucose yield of R80. The highest glucose yield (82.57%) was obtained when 15% R80-180 was mixed with R80. However, the glucose content decreased when R180 was mixed with R80 because of its high ash content.

Low-temperature, solution-processed perovskite solar cells (PSCs), which utilized organic poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] (PTB7) as a hole-transport layer (HTL), achieved a power conversion efficiency (PCE) as high as 13.29% when fabricated in ambient air. Through a comparative study, we demonstrate this PCE value to be superior compared to its counterparts with spiro-OMeTAD or P3HT as the HTL; the superiority consists of a higher fill factor (FF) and open-circuit voltage (Voc). By probing the absorption spectrum of CH3NH3PbI3−xClx before and after spin-coating the PTB7, it is discovered that the spin coating of PTB7 has little influence on the quality of the perovskite films. Furthermore, it is shown that PTB7 possesses higher conductivity compared with conventional HTLs, including spiro-OMeTAD, P3HT and PCDTBT. Moreover, in order to further improve device performance, the prevalent additives lithium bis (trifluoromethylsulphony) imide (LiTFSI) and 4-tert-butylpyridine (t-Bp) are investigated, along with a post-annealing process that is applied to the whole device. The results presented here and the overall fabrication method represent a helpful new approach for fabricating highly efficient perovskite-based photovoltaic devices.

Nanostructured MoS2 is very promising as an electrocatalyst for hydrogen evolution due to a greater number of active edge sites. However, a very large resistance between basal planes decreases the overall efficiency of hydrogen evolution, and greatly limits its application in industry. Herein we develop a facile strategy to synergistically increase the number of active edge sites and the conductivity of MoS2. MoS2 nanosheet arrays can be grown vertically on a carbon fiber cloth (CFC) substrates by a facile strategy. On the one hand, ammonium fluoride in the reaction system could effectively etch the inert basal plane of the MoS2 nanosheets, leading to the formation of pits in the inert basal plane of the MoS2 nanosheets. Thereby the number of active edge sites is significantly increased. On the other hand, the vertical growth of MoS2 nanosheet arrays on CFCs can significantly decrease the resistance of MoS2-based electrocatalysts. As a result, the MoS2-based electrocatalysts exhibit excellent catalytic activity for hydrogen evolution reactions, with a small Tafel slope and a large cathodic current density. Moreover, the CFC can be repeatedly utilized as a template to grow ultrathin MoS2 nanosheet arrays for HERs. The excellent activity and recyclable utilization, as well as mass production, indicate that the composite has promising applications in industry.

A hydrothermal method was developed to grow ultrathin MoS2 nanosheets, with an expanded spacing of the (002) planes, on carbon nanotubes. When used as a sodium-ion battery anode, the composite exhibited a specific capacity of 495.9 mAh g–1, and 84.8% of the initial capacity was retained after 80 cycles, even at a current density of 200 mA g–1. X-ray diffraction analyses show that the sodiation/desodiation mechanismis based on a conversion reaction. The high capacity and long-term stability at a high current ate demonstrate that the composite is a very promising candidate for use as an anode material in sodium-ion batteries.

An ultrahigh resolution probe technique for charactering nanoscale Seebeck coefficient was developed based on a modified conductive AFM probe with local heating function. The heated AFM conductive tip realizes nanoscale thermal contact between the AFM tip and the thermoelectric samples and successfully excites nanoscale thermoelectric signal. Excellent agreement was found between nanoscale Seebeck coefficient values and their corresponding macroscopy measurements in thermoelectric bulk and thin films. Such AFM-based thermoelectric probe technique provides a very convenient and promising tool for measuring nanoscale thermoelectric parameters with ultrahigh resolution up to 15 nm.

We experimentally demonstrate cascaded Raman scattering continuum generation at 1.0–1.3 μm with pulse energy of 47 nJ by utilizing a commercially available all-normal-dispersion single-mode fiber (SMF) with a low threshold pump power. We achieve passively mode-locked all-fiber lasing by nonlinear polarization rotation technique. Continuous Raman gain is obtained by the same SMF in every roundtrip because of the ring-cavity configuration, which makes it possible to achieve high-order Raman Stokes waves by a short fiber length. Limited by the pump power, the maximum output average power and peak power are 87.4 and 339 mW, but it has great potential to be improved. These make it an ideal continuum source for many applications, such as optical coherence tomography.

Graphene/ZnO (G/ZnO) composites were synthesized for the first time by a wet chemical method. X-ray diffraction and transmission electron microscopy analyses demonstrated that ZnO nanoparticles with an average diameter of about 5 nm uniformly covered the graphene surfaces. G/ZnO composites were dispersed in methyl methacrylate (MMA), polymerized at 75 °C for 30–35 min, and finally, dried at 45 °C for 10 h, to afford G/ZnO/PMMA organic glasses. UV–visible spectra showed that the band gaps of the G/ZnO/PMMA organic glasses were about 3.54 eV, larger than that of bulk ZnO because of the small size effect of ZnO nanoparticles. The nonlinear optical (NLO) and optical limiting (OL) properties of the G/ZnO/PMMA organic glasses were investigated by a modified Z-scan technique. The total NLO coefficient α 2 of the G/ZnO/PMMA organic glass was as high as 1530 cm/GW, which was approximately 5.6 and 7.8 times larger than those of G/PMMA and ZnO/PMMA organic glasses. The enhanced NLO properties of the G/ZnO/PMMA organic glasses led to excellent OL performance, which was attributed to the positive synergistic effects between graphene and ZnO.

Flexible lithium-ion batteries are the key to powering a new generation of flexible electronics such as roll-up displays, smart electronics, and wearable devices. Here we report, for the first time, one-step hydrothermal synthesis of a three-dimensional (3D) hierarchical MoS2 nanoflake array/carbon cloth which shows potential for improving the performance of flexible lithium-ion batteries. Structural characterizations show that the 3D hierarchical MoS2 nanoflake array/carbon cloth has a similar ordered woven structure to the bare carbon cloth. Each carbon microfiber is covered with many highly ordered 3D MoS2 nanoflake arrays, and a typical MoS2 nanoflake, with expanded spacing of the (002) crystal plane, has a uniform width of about 400 nm and a thickness of less than 15 nm. The flexible 3D MoS2 nanoflake array/carbon cloth as a flexible lithium-ion battery anode has a high reversible capacity of 3.0–3.5 mA h cm−2 at a current density of 0.15 mA cm−2 and outstanding discharging/charging rate stability. Moreover, a fabricated full battery, with commercial LiCoO2 powder and the hierarchical architectures as electrodes, exhibits high flexibility and good electrochemical performance, and can light a commercial red LED even after 50 cycles of bending the full battery.

MoS2 nanoflake array films on different glass substrates were fabricated by an in situ growth method. The nonlinear absorption (NLA) properties of the MoS2 nanoflake array films were investigated by an open-aperture Z-scan technique. The MoS2 nanoflake array films exhibited different NLA properties dependent on the input energy. In the case of lower input energy, the films exhibited saturable absorption (SA); however, if the input energy was increased, a changeover from SA to reverse saturable absorption (RSA) was observed. The interesting NLA properties of the films could be attributed to the competition between the ground-state absorption and the excited-state absorption in terms of the energy-level model of MoS2.

Pore connectivity of lacustrine shales was inadequately documented in previous papers. In this work, lacustrine shales from the lower Cretaceous Shahezi Formation in the Changling Fault Depression (CFD) were investigated using field emission scanning electron microscopy (FE-SEM), mercury intrusion capillary pressure (MICP), low pressure gas (CO2 and N2) sorption (LPGA) and spontaneous fluid imbibition (SFI) experiments. The results show that pores observed from FE-SEM images are primarily interparticle (interP) pores in clay minerals and organic matter (OM) pores. The dominant pore width obtained from LPGA and MICP data is in the range of 0.3&ndash, 0.7 nm and 3&ndash, 20 nm. The slopes of n-decane and deionized (DI) water SFI are in the range of 0.34&ndash, 0.55 and 0.22&ndash, 0.38, respectively, suggesting a mixed wetting nature and better-connected hydrophobic pores than hydrophilic pores in the Shahezi shales. Low pore connectivity is identified by the dominant nano-size pore widths (0.3&ndash, 20 nm), low DI water SFI slopes (around 0.25), high geometric tortuosity (4.75&ndash, 8.89) and effective tortuosity (1212&ndash, 6122). Pore connectivity follows the order of calcareous shale &gt, argillaceous shale &gt, siliceous shale. The connected pores of Shahezi shales is mainly affected by the high abundance and coexistence of OM pores and clay, carbonate minerals host pores.

Nitrogen-doped carbon materials with controllable morphologies were prepared via a soft template method using chitosan as the carbon and nitrogen source and F127 or ionic liquid as the template. The performance of the materials as electrodes and adsorbents for carbon dioxide removal were evaluated. Carbon spheres (CSs) with developed micropore structures were obtained without a template, whereas a tubular structure (CSF) containing mesopores with long-range order was obtained using F127. Layered carbon (CSI) containing micro-/mesopores with short- and long-range order was obtained using an ionic liquid. The samples exhibited graphite-like structure and the soft template increased the graphitization degree. Nitrogen existed mainly in the form of pyridine and pyridone groups in CSs and CSF and as pyridine, pyridone, and quaternary groups in CSI. The specific capacitances of CSs, CSF, and CSI were 144, 161, and 178 F g-1, respectively, at a current density of 1.0 A g-1 in 1 M sulfuric acid. The carbon dioxide adsorption capacities of CSs, CSF, and CSI were 142, 73, and 115 mg g-1, respectively; CSs displayed the highest value because of its developed micro- and ultramicroporous structure. Our results indicated that these carbon materials with various morphologies can be used as both electrodes and adsorbents.

Graphene/MoS2 (G/MoS2) composites were synthesized for the first time by a hydrothermal method, and then were dispersed in methyl methacrylate (MMA) to fabricate organic glass by a casting method. Here, the poly(methylmethacrylate) (PMMA) host can be obtained by the polymerization of MMA. The nonlinear absorption (NLA) properties of the G/MoS2/PMMA organic glasses were investigated by using an open-aperture Z-scan technique. The experimental results showed that the G/MoS2/PMMA organic glasses (the NLA coefficient β, was up to 2110 cm/GW) exhibited enhanced reverse saturable absorption (RSA) properties compared to G/PMMA (β = 242 cm/GW) and MoS2/PMMA (β = 365 cm/GW) organic glasses. The enhanced mechanism of RSA was analyzed in terms of the energy-level diagram of graphene and MoS2. The G/MoS2/PMMA organic glasses have very promising applications in optical devices such as optical limiters and optical shutters.

The ZnO nanowire (NW) array/TiO2 nanoparticle (NP) composite photoelectrode with controllable NW aspect ratio has been grown from aqueous solutions for the fabrication of dye-sensitized solar cells (DSSCs), which combines the advantages of the rapid electron transport in ZnO NW array and the high surface area of TiO2 NPs. The results indicate that the composite photoelectrode achieves higher overall photoelectrical conversion efficiency (η) than the ZnO NW alone. As a result, DSSCs based on the ZnO NW array/TiO2 NP composite photoelectrodes get the enhanced photoelectrical conversion efficiency, and the highest η is also achieved by rational tuning the aspect ratio of ZnO NWs. With the proper aspect ratio (ca. 6) of ZnO NW, the ZnO NW array/TiO2 NP composite DSSC exhibits the highest conversion efficiency (5.5 %). It is elucidated by the dye adsorption amount and interfacial electron transport of DSSCs with the ZnO NW array/TiO2 NP composite photoelectrode, which is quantitatively characterized using the UV-Vis absorption spectra and electrochemical impedance spectra. It is evident that the DSSC with the proper aspect ratio of ZnO NW displays the high dye adsorption amount and fastest interfacial electron transfer.

CuO nanobelts were successfully prepared by a wet-chemical method assisted by ultrasonic irradiation. The structure characterizations for samples obtained under different ultrasonic time clearly demonstrated that Cu(OH) 2 nanorods were firstly formed, and then transformed into one-dimensional (1D) Cu(OH) 2 /CuO core–shell nanostructures, and into CuO nanobelts with an increase of ultrasonic time through an interesting epitaxial growth process. The length and width of the nanobelts were 0.5–1.2 μm and 60 nm, respectively. The sensor response of the nanobelts was about 1.2–100 ppb H 2 S gas at a working temperature of 135 °C. Moreover, the CuO nanobelts had almost not response to 10 ppm H 2 , NH 3 , CO and CH 4 at 135 °C. Thus, the CuO nanobelts are very promising for fabrication of H 2 S gas sensor.

We demonstrate a high-energy linearly polarized pulsed fiber laser for ultrasonic generation based on a master oscillator power amplification (MOPA) scheme, which delivers nanosecond pulses with duration of 4.8 ns and pulse energy of 476 μJ at the repetition rate of 50 kHz. The MOPA is seeded by a gain switch semiconductor laser diode at 1064 nm. In the pre-amplification stages, a double-pass amplification structure is designed and successfully applied to amplify the low-power seed laser for the consideration of suppressing amplified spontaneous emission, decreasing the number of amplification stages, and reducing the nonlinear effects. A highly ytterbium-doped fiber is utilized in the main amplifier to shorten the fiber length and reduce the fiber nonlinearity. The average power is finally boosted to 23.8 W with corresponding optical-to-optical efficiency of 66.9% and a polarization extinction rate of ∼10.5 dB. The corresponding peak power is calculated to be 87.1 kW. Finally, the established laser system is successfully used for ultrasonic generation based on a line excitation configuration and grating excitation configuration, and clear surface acoustic wave signals are detected. Many potential applications in laser ultrasonics can be foreseen.