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The palladium (Pd)-catalyzed Suzuki reaction is widely applied in the pharmaceutical industry, where constructing highly active and low-cost Pd sites are impendent. Here, we report the fabrication ...

It is highly important to develop ultrastable electrode materials for Li-ion batteries (LIBs), especially in the low temperature. Herein, we report Fe3+-stabilized Ti3C2Tx MXene (donated as T/F-4:1) as the anode material, which exhibits an ultrastable low-temperature Li-ion storage property (135.2 mA h g−1 after 300 cycles under the current density of 200 mA g−1 at −10 °C), compared with the negligible capacity for the pure Ti3C2Tx MXene (∼26 mA h g−1 at 200 mA g−1). We characterized as-made T/F samples via the X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FT-IR) and Raman spectroscopy, and found that the terminated functional groups (-O and -OH) in T/F are Li+ storage sites. Fe3+-stabilization makes -O/-OH groups in MXene interlayers become active towards Li+, leading to much more active sites and thus an enhanced capacity and well cyclic stability. In contrast, only -O/-OH groups on the top and bottom surfaces of pure Ti3C2Tx MXene can be used to adsorb Li+, resulting in a low capacity. Transmission electron microscopy (TEM) and XPS data confirm that T/F-4:1 holds the highly stable solid electrolyte interphase (SEI) layer during the cycling at −10 °C. Density functional theory (DFT) calculations further uncover that T/F has fast diffusion of Li+ and consequent better electrochemical performances than pure Ti3C2Tx MXene. It is believed that the new strategy used here will help to fabricate advanced MXene-based electrode materials in the energy storage application.

The study aims to explore the preparation of aviation mechanical carbon fiber reinforced plastics (CFRP) and the properties of CFRP composites. Taking the aero box body as an example, the mechanical properties of CFRP are studied. The preparation of CFRP is analyzed by searching the data. CFRP plates are explored according to the stress analysis of composite materials. The finite element analysis software ANSYS Workbench and UG software are adopted to build the 3D model of the aero box body. After adding materials in ANSYS Workbench and simplifying the UG model, the finite element analysis of the model is carried out by computer. The 3D model of the aero box is constructed, the finite element analysis of the aero box is carried out, and the mechanical properties of CFRP are explored. In this study, the possibility of the practical application of CFRP in the aviation box body lightweight is clarified, which gives a direction for the subsequent actual molding and guides the application of CFRP in aviation field.

It has been demonstrated that substantial electric power can be produced by a liquid-based triboelectric nanogenerator (TENG). However, the mechanisms regarding the electrification between a liquid and a solid surface remain to be extensively investigated. Here, the working mechanism of a droplet-TENG was proposed based on the study of its dynamic saturation process. Moreover, the charge-transfer mechanism at the liquid-solid interface was verified as the hybrid effects of electron transfer and ion adsorption by a simple but valid method. Thus, we proposed a model for the charge distribution at the liquid-solid interface, named Wang's hybrid layer, which involves the electron transfer, the ionization reaction, and the van der Waals force. Our work not only proves that TENG is a probe for investigating charge transfer at interface of all phases, such as solid-solid and liquid-solid, but also may have great significance to water energy harvesting and may revolutionize the traditional understanding of the liquid-solid interface used in many fields such as electrochemistry, catalysis, colloidal science, and even cell biology.

Heteroatom doping in nanomaterials can import new active sites and promote catalytic activity. Here we report that Mn-doped Co3O4 nanorods (Mnx-Co3O4) via substituting Mn3+ (t2g3-eg1) for Co3+ (t2g...

The upgrade of the laser pump time-resolved X-ray probes, namely time-resolved X-ray absorption spectroscopy (TR-XAS) and X-ray diffraction (TR-XRD), implemented at the Beijing Synchrotron Radiation Facility, is described. The improvements include a superbunch fill, a high-efficiency fluorescence collection, an efficient spatial overlap protocol and a new data-acquisition scheme. After upgrade, the adequate TR-XAS signal is now obtained in a 0.3 mM solution, compared with a 6 mM solution in our previous report. Furthermore, to extend application in photophysics, the TR-XAS probe is applied on SrCoO2.5 thin film. And for the first time, TR-XAS is combined with TR-XRD to simultaneously detect the kinetic trace of structural changes in thin film.

A dual-site catalyst allows for a synergetic reaction in the close proximity to enhance catalysis. It is highly desirable to create dual-site interfaces in single-atom system to maximize the effect. Herein, we report a cation-deficient electrostatic anchorage route to fabricate an atomically dispersed platinum–titania catalyst (Pt1O1/Ti1−xO2), which shows greatly enhanced hydrogen evolution activity, surpassing that of the commercial Pt/C catalyst in mass by a factor of 53.2. Operando techniques and density functional calculations reveal that Pt1O1/Ti1−xO2 experiences a Pt−O dual-site catalytic pathway, where the inherent charge transfer within the dual sites encourages the jointly coupling protons and plays the key role during the Volmer–Tafel process. There is almost no decay in the activity of Pt1O1/Ti1−xO2 over 300 000 cycles, meaning 30 times of enhancement in stability compared to the commercial Pt/C catalysts (10 000 cycles).

A polarization splitter based on dual-core photonic crystal fiber (PCF) with tellurite glass was proposed. The birefringence of the splitter was improved by introducing elliptical air holes. The full vector finite element method is used to analyze the impacts of structural parameters on the coupling length. The results show that the elliptical size is reasonably changed, the extinction ratio can reach 107.21 dB at the wavelength of 1.55 μ m , the length of the splitter is 89.05 μ m , and the bandwidth is 150 nm when the extinction ratio is more than 20 dB. Besides, we also compare the characteristics of tellurite glass and silica glass photonic crystal fiber polarization beam splitters with the same structural parameters.

Performance degradation caused by the oxidation of carbon anodes during capacitive deionization (CDI) remains a major problem that may greatly restrict the practical application of CDI. To improve the cyclic stability of CDI, carbon-based anode materials were replaced by pseudocapacitive MnO2 in this work. The cation-selective MnO2 anode was assembled with an anion-selective quaternized poly(4-vinylpyridine)-coated activated carbon cathode into a hybrid CDI cell. The cell exhibited inverted CDI performance with a wide operating voltage window of 1.4 V and a salt adsorption capacity (SAC) of 14.9 mg/g in 500 mg/L NaCl. The SAC retention ratio of the cell can be as high as 95.4% after 350 adsorption–desorption cycles at 1.0/0 V, while that of the CDI cell consisting of activated carbon electrodes was only 15.7% after 285 cycles. The enhanced cyclic stability of the hybrid CDI cell is attributed to the employment of the MnO2 anode, which avoided the use and oxidation of carbon anodes.

Capacitive deionization (CDI) is an emerging technology for removing charged ions from saline water and has attracted much attention in recent years. Developing a new electrode material with a reasonable structure is of great significance for obtaining high CDI performance. Herein, two-dimensional (2D) boron carbon nitride (BCN) nanosheets were fabricated using a new approach, which uses g-C3N4 as both the template and the nitrogen source, boric acid as the boron source and a subsequent pyrolysis process. The as-prepared BCN nanosheets show a pore structure with a high specific surface area and were investigated as CDI electrode materials for the first time. Moreover, the high heteroatom content, with a potential synergistic effect of N and B atoms, results in fast ion diffusion and good charge transfer ability. The BCN nanosheets demonstrate a high salt adsorption capacity of 13.6 mg g−1 at 1.4 V applied voltage when the initial NaCl concentration is 500 mg L−1. The BCN electrodes also exhibited better cyclic stability over 15 adsorption–desorption cycles. These results indicate that BCN nanosheets should be practicable candidates for high performance CDI electrode materials.

Salinity gradient energy (SGE) is the energy available from the salinity difference between freshwater and saltwater. Herein, we propose a concentration capacitor as a novel capacitive mixing (CapMix) technique to harvest SGE. The concentration capacitor comprises identical electrodes and a membrane that separates concentrated and diluted solutions that alternately flow through the capacitor. Graphene hydrogel (GH) electrodes and a filtration membrane (FM) or an anion exchange membrane (AEM) are used to construct GH//FM//GH and GH//AEM//GH concentration capacitors. These concentration capacitors show excellent performance in harvesting SGE, particularly the GH//AEM//GH concentration capacitor, whose voltage rise and average power density can reach 288.5 mV and 482.4 mW m−2, respectively, which are higher than those obtained with other CapMix techniques. The outstanding performance is associated with the double-channel construction, the membrane potential, and the macroporous structure and abundant negative charge of the GH electrodes. Our results show that the concentration capacitor is a promising approach for efficiently extracting SGE.

The extraction of salinity gradient energy remains a challenging task. In this paper, we propose a new method for the extraction of salinity gradient energy by using a hybrid capacitor, which consists of a battery electrode and a porous carbon electrode. The potentials of the Na4Mn9O18 (NMO) and activated carbon (AC) electrodes show opposite dependencies on salt concentration, so that as fresh water and salt water flow alternately through the hybrid capacitor, the voltage difference between the electrodes can be increased by 110 mV. Our results demonstrate the viability of this new method to harvest salinity gradient energy without using membranes or precious metals.

Unlike their bulk counterpart, Cux Iny S quantum dots (QDs) prepared by an aqueous synthetic approach, show promising activity for photocatalytic hydrogen evolution, which is competitive with the state-of-the-art Cd chalcogen QDs. Moreover, the as-prepared Cux Iny S QDs with In-rich composition show much better efficiency than the stoichiometric ones (Cu/In=1:1).

Capacitive deionization (CDI) is an emerging technology that uniquely integrates energy storage and desalination. In this work, porous carbon nanosheets (PCNSs) with an ultrahigh specific surface area of 2853 m2/g were fabricated by the simple carbonization of starch followed by KOH activation for the electrode material of photovoltaic CDI. The CDI cell consisting of PCNSs electrodes exhibited a high salt adsorption capacity (SAC) of 15.6 mg/g at ∼1.1 V in 500 mg/L NaCl as well as high charge efficiency and low energy consumption. KOH activation played a key role in the excellent CDI performance as it not only created abundant pores on the surface of PCNSs but also made it fluffy and improved its graphitization degree, which are beneficial to the transport of ions and electrons. PCNSs are supposed to be a promising candidate for CDI electrode materials. The combination of solar cells and CDI may provide a new approach to reduce the energy cost of CDI and boost its commercial competitiveness.

Time-resolved X-ray absorption spectroscopy (TR-XAS), based on the laser-pump/X-ray-probe method, is powerful in capturing the change of the geometrical and electronic structure of the absorbing atom upon excitation. TR-XAS data analysis is generally performed on the laser-on minus laser-off difference spectrum. Here, a new analysis scheme is presented for the TR-XAS difference fitting in both the extended X-ray absorption fine-structure (EXAFS) and the X-ray absorption near-edge structure (XANES) regions. R-space EXAFS difference fitting could quickly provide the main quantitative structure change of the first shell. The XANES fitting part introduces a global non-derivative optimization algorithm and optimizes the local structure change in a flexible way where both the core XAS calculation package and the search method in the fitting shell are changeable. The scheme was applied to the TR-XAS difference analysis of Fe(phen)3 spin crossover complex and yielded reliable distance change and excitation population.

Efficient removal of lead from aqueous media remains a serious task for public health and environment. Here polyacrylonitrile (PAN) monolith is fabricated by means of thermally induced phase separation (TIPS), a novel method that can be used for the preparation of hierarchically structured monolith without any templates assisted. Three hierarchically structured adsorbents (D-PAN, H-PAN, A-PAN) based on PAN monolith were successfully prepared by reacting with diethylenetriamine (DETA), sodium hydroxide, and hydroxylamine hydrochloride, respectively. The Pb (II) adsorption ability of all modified samples was determined by a series of batch tests. Experimental data illustrated that all samples showed excellent Pb (II) adsorption ability and the maximum adsorption capacity of D-PAN, H-PAN, and A-PAN was 144 mg g−1, 206 mg g−1 and 242 mg g−1, respectively. The feasible preparation of hierarchically monolithic adsorbents with high adsorption capacities opens a new expectation in the potential application for engineering.

As a well-known phenomenon, contact electrification (CE) has been studied for decades. Although recent studies have proven that CE between two solids is primarily due to electron transfer, the mechanism for CE between liquid and solid remains controversial. The CE process between different liquids and polytetrafluoroethylene (PTFE) film is systematically studied to clarify the electrification mechanism of the solid-liquid interface. The CE between deionized water and PTFE can produce a surface charges density in the scale of 1 nC cm-2 , which is ten times higher than the calculation based on the pure ion-transfer model. Hence, electron transfer is likely the dominating effect for this liquid-solid electrification process. Meanwhile, as ion concentration increases, the ion adsorption on the PTFE hinders electron transfer and results in the suppression of the transferred charge amount. Furthermore, there is an obvious charge transfer between oil and PTFE, which further confirms the presence of electron transfer between liquid and solid, simply because there are no ions in oil droplets. It is demonstrated that electron transfer plays the dominant role during CE between liquids and solids, which directly impacts the traditional understanding of the formation of an electric double layer (EDL) at a liquid-solid interface in physical chemistry.

Capacitive deionization (CDI) is a promising technology for desalination due to its advantages of low driven energy and environmental friendliness. However, the ion removal capacity (IRC) of CDI is insufficient for practical application because such a capacity is limited by the available surface area of the carbon electrode for ion absorption. Thus, the development of a novel desalination technology with high IRC and low cost is vital. Here, a membrane-free hybrid capacitive deionization system (HCDI) with hollow carbon@MnO2 (HC@MnO2) to capture sodium via redox reaction and hollow carbon sphere with net positive surface charges (PHC) for chloride adsorption is introduced. The as-obtained HC@MnO2 with unique structure and high conductivity can improve the utilization of MnO2 pseudocapacitive electrodes. Meanwhile, the PHC can selectively adsorb Cl- and prevent the adsorption of Na+ due to electrostatic repulsion. As expected, the membrane-free HCDI system demonstrates excellent desalination performance. The system's IRC and maximum removal rate are 30.7 mg g-1 and 7.8 mg g-1 min-1, respectively. Moreover, the proposed system has a low cost because of the absence of expensive ion exchange membranes (IEM), which is suitable for practical application. The excellent performance of this HCDI makes it a promising desalination technology for future use.

Here we present a facile aqueous approach to synthesize heterostructured CdSe/CdS QDs with all-inorganic chalcogenide S2− ligands under mild conditions. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and steady-state emission spectroscopy demonstrate that the heterostructured CdSe/CdS QDs with sulfur-rich surface composition are formed by heterogeneous nucleation of Cd2+ and S2− precursors on the CdSe QDs. After adsorption of small Ni(OH)2 clusters over the surface in situ, the CdSe/CdS–Ni(OH)2 photocatalyst enables H2 production efficiently with an internal quantum yield of 52% under visible light irradiation at 455 nm, up to an 8-fold increase of activity to that of spherical CdSe QDs–Ni(OH)2 under the same conditions. Femtosecond transient absorption spectroscopy, X-ray transient absorption (XTA) spectroscopy, steady-state and time-resolved emission spectroscopy show that the quasi-type-II band alignment in the CdSe/CdS heterostructure is responsible for the efficiency enhancement of light harvesting and surface/interfacial charge separation in solar energy conversion. The unprecedented results exemplify an easily accessible pattern of aqueous synthesis of all-inorganic heterostructured QDs for advanced photosynthetic H2 evolution.

Capacitive mixing (CapMix) is an emerging technique that uses supercapacitors for harvesting salinity gradient energy. Here, positively charged quaternized poly(4-vinylpyridine) coated activated carbon and negatively charged nitric acid oxidized activated carbon are employed as electrodes for asymmetric CapMix (Asy-CapMix), enabling the production of electricity via four-step or two-step energy generation cycles without using an external power source and selective membranes. The voltage rise of this capacitor is 150.0 mV, and the average power density can reach as high as 65.0 mW m−2. Both values are higher than those of CapMix using symmetric electrodes and an external power source or selective membranes and better than those of previous Asy-CapMix, including those with external power supplies. Such superior performance can be attributed to the high surface charge density and the good conductivity of the chemically modified activated carbon electrodes, which may give insight into the design of electrodes for high performance Asy-CapMix.

The desalination performance of capacitive deionization (CDI) technology is governed by electrode material properties, such as specific surface area, pore size and structure, surface functional groups, electrode geometry, and electrical conductivity. However, few studies have been conducted regarding the impact of the electrical conductivity of electrode materials on the desalination performance of CDI. In this study, monolithic composite web electrodes are fabricated. These electrodes are composed of reduced graphene oxide/activated carbon nanofiber with tuned conductivity by using an ultrasound-assisted electrospinning method. Freestanding monolithic carbon nanofiber webs function as a framework that prevents graphene sheets from restacking. The conductive graphene network helps quickly transfer electrons across the matrix while the ions are efficiently stored in the pores of the electrodes; as a result, a high electrosorption capacity for NaCl of 9.2 mg/g is achieved. The electrical conductivity of the electrodes is correlated with the ion removal efficiency of desalination. Results show that the electrosorption capacity of desalination governed by the electric double-layer scheme can be improved by increasing the electrical conductivity of the electrodes. These findings may provide new insights into the design and fabrication of novel porous electrode materials and elucidate the importance and effects of electrode conductivity on CDI.

Efficient visible-light-driven hydrogen evolution (VLD-HER) is the most desirable for utilizing solar energy, but it remains a significant challenge to fabricate advanced photocatalysts. Herein, we report on a single-atom ruthenium doped monolayered TiO2 nanosheet catalyst (Ru1/TiNS). Unlike pure TiO2 with no VLD-HER activity, Ru1/TiNS enables efficient H2 evolution with a mmol h−1 g−1 magnitude (4.81) under visible light, comparable to 8.95 mmol h−1 g−1 under full light spectrum. Various ex-/in-situ characterizations and theoretical calculations reveal that the single-atom Ru1 introduces an impurity energy level, allowing light absorption up to 700 nm, and an oxygen vacancy around Ru1 tends to be a charge trapping site, promoting rapid photogenerated electron separation and transportation. This study provides a promising catalyst-design strategy for high-efficiency hydrogen production using solar energy.

This study reports the synthesis of ultrafine NiFe-layered double hydroxide (NiFe-LDH) nanosheets, possessing a size range between 1.5 and 3.0 nm with a thickness of 0.6 nm. Abundant metal and oxygen vacancies impart the ultrafine nanosheets with semi-metallic character, and thus superior charge transfer properties and electrochemical water oxidation performance with overpotentials (η) of 254 mV relative to monolayer LDH nanosheets (η of 280 mV) or bulk LDH materials (η of 320 mV) at 10 mA cm−2. These results are highly encouraging for the future application of ultrafine monolayer LDH nanosheets in electronics, solar cells, and catalysis.

Semiconducting quantum dots (QDs) have recently triggered a huge interest in constructing efficient hydrogen production systems. It is well established that a large fraction of surface atoms of QDs need ligands to stabilize and avoid them from aggregating. However, the influence of the surface property of QDs on photocatalysis is rather elusive. Here, the surface regulation of CdSe QDs is investigated by surface sulfide ions (S2- ) for photocatalytic hydrogen evolution. Structural and spectroscopic study shows that with gradual addition of S2- , S2- first grows into the lattice and later works as ligands on the surface of CdSe QDs. In-depth transient spectroscopy reveals that the initial lattice S2- accelerates electron transfer from QDs to cocatalyst, and the following ligand S2- mainly facilitates hole transfer from QDs to the sacrificial agent. As a result, a turnover frequency (TOF) of 7950 h-1 can be achieved by the S2- modified CdSe QDs, fourfold higher than that of original mercaptopropionic acid (MPA) capped CdSe QDs. Clearly, the simple surface S2- modification of QDs greatly increases the photocatalytic efficiency, which provides subtle methods to design new QD material for advanced photocatalysis.

3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) nanorods as an n-type organic semiconductor are utilized to construct a powder-based photocatalytic water oxidation system with cobalt oxide as a cocatalyst, which achieved an apparent quantum efficiency of 4.6 ± 0.3% under visible light irradiation at 410 nm.

Tb3+ activated LaPO4 nano-phosphors have been prepared by a hydrothermal method. Luminescence spectra in VUV-vis range as well as fluorescence decays were studied for bulk and nano-phosphors. Bulk sample exhibits a relatively fast decay time. The D-5(3) emissions from Tb3+ ions increase under X-ray excitation in comparison with that under ultraviolet light excitation. X-ray absorption near-edge structure (XANES) was employed to study the chemical environment and energy transfer efficiency to optical emission. XANES results across different element absorption edges indicate that the chemical environment does not change significantly, only oxygen contributes to luminescence negatively. (C) 2015 Elsevier B.V. All rights reserved.

A new kind of dual-core photonic crystal fiber polarization splitter based on tellurite glass is designed by introducing five elliptical air holes and octagonal lattice into the polarization splitter. The full vector finite element method and coupled-mode theory are used to study its characteristics. The structure parameters are optimized through the study of all parameters in the split structure. The results show that a polarization splitter with a short length of 105.156 μm can completely separate the two beams of polarization lights. And at the wavelength of 1.550 μm the extinction ratio can reach 124.920 dB. Meanwhile, the bandwidth is 165 nm when the extinction ratio is more than 20 dB and the wavelength range is from 1.467 to 1.632 μm, which covers the S + C + L wavelength bands. The bandwidth is 448 nm when the extinction ratio is more than 10 dB and the wavelength range is from 1.322 to 1.770 μm. The polarization splitter has a short length and a high extinction ratio and a wide bandwidth, which can be widely applied in large-capacity and integrated optical communication systems.

Cesium-based fully inorganic black-phase (BP) lead halide perovskites (such as α-, β-, and γ-CsPbI3) with excellent thermal stability and a decently high photovoltaic performance have attracted increasing attention. However, a below 200 C fabrication process of the desirable BP CsPbI3 has rarely been reported. Herein, the detailed crystal structure evolution of ambient-air-stable BP CsPbI3 prepared under low temperature conditions is investigated by exploiting the strong coordination bonding between C═O in polyvinylpyrrolidone (PVP) and Pb in CsPbI3 and inflection effect of PVP under annealing. It is found that ambient-air-stable BP CsPbI3 films are formed and the energy barrier for the long-term stable BP CsPbI3 formation is significantly reduced (the required annealing temperature is only 80 C). After optimization, the highest power conversion efficiencies (PCEs) of 4.0% and 10.0% are recorded for the 3% PVP-added devices with light absorbers annealed at 80 and 160 C, respectively. More importantly, the 3% PVP device annealed at 160 C maintains 80% of its original PCE after 5 months storage under ambient-air conditions.

A 9-12% Cr ferritic steel weld metal containing 1% Co partially substituted for nickel was prepared by submerged arc welding processing(SAW). The microstructures and creep properties of the weld metal have been investigated. The microstructure exhibited a fully tempered martensitic structure free of δ-ferrite. The creep properties of the obtained weld metal are inferior to that of the P92 base metal at 600 and 650 . The values of A and n for weld metal in Norton power law constitution at 650 are 1.12×10-21 and 8.14, respectively.

A 9% Cr ferritic steel weld metal containing 1% Co, partially substituted for nickel, was prepared by submerged arc welding (SAW) processing. The microstructure and creep properties of the weld metal were investigated. The microstructure exhibited a fully tempered martensitic structure free of δ-ferrite. The creep properties of the obtained weld metal were inferior to those of the P92 base metal at 600 and 650 °C. The values of A and n for weld metal in the Norton power law constitution at 650 °C are 1.1×10−21 and 8.1, respectively.

The size dependence of atomic relaxations, formation energies, and electronic structures of hexagonal [0001] zinc oxide (ZnO) nanotubes with diameters of up to 2.3 nm were studied using density-functional calculations. The formation energies per Zn–O pair in thick-walled hexagonal ZnO nanotubes were found to be mainly dependent on the wall thickness and not on the tube diameter. Thick-walled ZnO nanotubes are energetically more favorable than single-walled ZnO nanotubes. All ZnO nanotubes were found to be semiconducting, with band gaps larger than that of bulk ZnO. It was also found that the wall thickness of ZnO nanotubes strongly affects their shapes and the energies of the conduction bands, rather than their valence band maxima.