Packing Of Layers Research Articles

3-Methyl-2-(methyl-sulfan-yl)-5,5-diphenyl-3,5-di-hydro-4H-imidazol-4-one.

In the title mol-ecule, C17H16N2OS, the di-hydro-imidazolone ring is slightly puckered and the methyl-sulfanyl group is nearly coplanar with it. In the crystal, two sets of C-H⋯O hydrogen bonds form corrugated layers of mol-ecules parallel to the ac plane. The layers pack with normal van der Waals contacts between them.

Onsite treatment of decentralized rural greywater by ecological seepage well (ESW)

Seepage well, as an ancient facility for sewage collection and treatment in China, still has reference significance for effective treatment of source-separated greywater in rural China under the background of rural revitalization. This study surveyed the discharge characteristic of rural greywater, and proposed onsite treatment of decentralized rural greywater using a novel ecological seepage well (ESW). In northwestern China, four rural households produced greywater with an average quantity of 128–146 L/d, with chemical oxygen demand (COD) of 213.6–235.9 mg/L as the main pollutant. For treating greywater, ESW with ceramsite and zeolite mixed in the packing layers and metallic corrugated plates (MCPs) set in the aeration zone achieved higher removal efficiencies of COD, total phosphorous (TP), total nitrogen (TN) and ammonia nitrogen (NH4+-N). When the influent C/N ratio was 16, the enhanced removal performance was realized by cutoff duration of 9 h, and the effluent met the Chinese standard for irrigation water quality with COD, TP, TN and NH4+-N removal efficiencies of 88.58%, 65.60%, 92.94% and 93.65%, respectively. Under the optimal condition, mechanism of pollutant removal by ESW was investigated. The variation of EPS and microbial morphology along the height illustrated that a micro-aerobic environment was formed in the lower layer of ESW. High throughput sequencing indicated plentiful denitrifying bacteria (DNB) and denitrifying phosphate accumulating organisms (DNPAOs), together with a higher relative abundance of ammonia oxidizing bacteria (AOB) than nitrite oxidizing bacteria (NOB) in the lower layer, which was relative to simultaneous nitrification, denitrification and phosphorous removal. This study provided theoretical and practical support for effective treatment mode of rural sewage.

Multilayer RGOx＆PESy films for efficient electromagnetic shielding performance in a wide temperature range

In this work, the alternating multi-layer structured reduced graphene oxide＆polyether sulfone (RGOx&PESy) film is fabricated via a facile thermal pressure process, which has independently aligned packing layers to ensure the conductive network. The electromagnetic interference (EMI) shielding performance of the RGOx＆PESy film can be adjusted with facility by controlling the layer number of the pure RGO and PES films. At a fixed thickness of 0.35 mm, the shielding performance of the multi-layer structured films increases with the increased layer number of the RGO films. Especially, when the number of RGO film is seven, the RGO7&PES6 film provides an efficient EMI shielding performance of about 45 dB in the whole X-band with a low filler content of 7.39 wt%. Moreover, due to the excellent temperature stability of both RGO and PES, the effective EMI shielding performance can be maintained in the wide temperature range of 298 ∼ 473 K. This study provides a facile method for preparing the RGO-based EMI shielding film materials with excellent high-temperature resistance and ultra-low filler content.

Reversible transformation of peptide assembly between densified-polysarcosine-driven kinetically and helix-orientation-driven thermodynamically stable morphologies.

Stimuli-responsive transformable biomaterials development can be manipulated practically by fine-tuning the built-in molecular design of their structural segments. Here, we demonstrate a peptide assembly by the bola-type amphiphilic polypeptide, glycolic acid-polysarcosine (PSar)13-b-(L-Leu-Aib)6-b-PSar13-glycolic acid (S13L12S13), which shows morphological transformations between hydrophilic chain-driven and hydrophobic unit-driven morphologies. The hydrophobic α-helical unit (L-Leu-Aib)6 precisely controls packing in the hydrophobic layer of the assembly and induces tubule formation. The densified, hydrophilic PSar chain on the assembly surface becomes slightly more hydrophobic as the temperature increases above 70 °C, starting to disturb the helix-helix interaction-driven formation of tubules. As a result, the S13L12S13 peptide assembly undergoes a reversible vesicle-nanotube transformation following a time course at room temperature and a heat treatment above 80 °C. Using membrane fluidity analysis with DPH and TMA-DPH and evaluating the environment surrounding the PSar side chain with NMR, we clarify that the vesicle was in a kinetically stable state driven by the dehydrated PSar chain, while the nanotube was in a thermodynamically stable state.

Pressure-Induced Structural Effects in the Square Lattice (sql) Topology Coordination Network Sql-1-Co-NCS·4OX.

A high-pressure study of a switching coordination network of square lattice topology (sql) loaded with o-xylene (OX), [Co(4,4'-bipyridine)2(NCS)2] n ·4nC8H10 (sql-1-Co-NCS·4OX), was conducted up to approximately 1 GPa to investigate pressure-induced structural changes. Previous reports revealed that sql-1-Co-NCS exhibits multiple phases thanks to its ability to switch between closed (nonporous) and several open (porous) phases in the presence of various gases, vapors, and liquids. Networks of such properties are of topical interest because they can offer high working capacity and improved recyclability for gas adsorption. The monoclinic crystal structure of sql-1-Co-NCS·4OX at 100 K was previously reported to show an increase in interlayer separation of more than 100% compared to the corresponding closed phase, sql-1-Co-NCS, when exposed to gases or vapors under ambient conditions. Herein, a tetragonal crystal form of sql-1-Co-NCS·4OX (space group I4/mmm, Phase I) that exists at 0.1 MPa/303 K is reported. Exposure of Phase I to high pressure using penetrable pressure transmitting media (OX and 1:1 vol MeOH/EtOH) did not result in further separation of the sql networks. Rather, compression of the crystals and release of adsorbed OX molecules occurred. These pressure-induced changes are discussed in terms of structural voids, framework conformation, and molecular packing of the sql layers. Although Phase I retained tetragonal symmetry throughout the investigated pressure range, the interlayer voids occupied by OX molecules were significantly reduced between 0.3 and 0.5 GPa; further compression above 0.5 GPa induced structural disorder. Additionally, analysis of the electron count present in the pores of sql-1-Co-NCS confirmed the multistep evacuation of OX molecules from the crystal, and two intermediate phases, Ia and Ib, differing in the OX loading level, are postulated.

Efficient capture of radioactive iodine by Ag-attached silica gel and its kinetics

• The removal rate of iodine by self-made Ag-attached silica gel is 98.62 % (wt.%). By selecting the intake air flow and humidity, the adsorption effect of silica gel can be changed. • For the design of Ag-attached silica gel adsorption column, selecting a larger inlet flow can improve the utilization rate of adsorption column. • The height of the packing layer in the adsorption column increases the mass transfer resistance, and changing the height can make the adsorption more complete. • Humidity has no effect on the adsorption of gaseous iodine on Ag-attached silica gel. • Yoon Nelson model can better simulate the dynamic adsorption behavior in the adsorption column of this experiment. In order to absorb the radioactive iodine produced during the reprocessing of spent fuel in nuclear power plants, in this study, the self-made silver content of 2–8 % Ag-attached silica gel was used as the adsorbent to adsorb radioactive iodine. Through dynamic adsorption method discussed with Ag-attached silica gel by the total flow at the inlet, the packing layer height in adsorption column under the factors such as temperature, humidity and adsorption of gaseous iodine adsorption effect. The experimental conclusions show that the saturated adsorption capacity is almost not affected by the different inlet flow rate, and the mass transfer resistance of the adsorption column increases under the condition of small inlet flow rate, resulting in longer adsorption time and more saturated adsorption. The height of Ag-attached silica gel packing layer in the adsorption column has little effect on the mass transfer resistance, and its saturated adsorption capacity increases with the increase of packing layer height. The adsorption effect is almost the same under different humidity. Under the same other conditions, by isothermal adsorption of Ag-attached silica gel at different temperatures, it can be found that the adsorption effect of Ag-attached silica gel at 150 °C is the best, which is consistent with the literature referred to. Through the kinetic simulation of silica gel with several different adsorption models, it can be found that the Yoon-Nelson model can well fit the dynamic adsorption process of gaseous iodine on silica gel with silver content of 2–8 %. The dynamic adsorption of iodine on silica gel shows that the adsorption capacity of gaseous iodine on silica gel is 40.60–238.83 mg/g. Moreover, Ag-attached silica gel has stable properties and lower cost than other sorbents. It is a promising adsorbent and can be widely used for radioactive iodine generated in the post-processing of spent fuel.

Revealing conflicting effects of solvent additives on morphology and performance of non-fullerene organic photovoltaics under different illuminance conditions

The use of solvent additives is effective for controlling the morphology and efficiency of non-fullerene bulk-heterojunction (BHJ) organic photovoltaics (OPVs) under both indoor and outdoor conditions. In this study, we examined the effects of solvent additives on the morphology and photovoltaic operation of non-fullerene OPVs under different illuminance conditions. Solvent additives (e.g., 1,8-diiodooctane) improved molecular packing and charge transport in non-fullerene BHJ layers, increasing the power conversion efficiency (PCE) under 1-sun illumination. However, incorporating the solvent additives promoted the formation of a crystallization-induced roughened surface and an isolated-non-fullerene domain in the intermixing region. These unexpected morphological features increased the degree of trap-assisted charge recombination and leakage current, significantly reducing the PCE of non-fullerene OPVs at low light levels corresponding to indoor lighting. Understanding the effect of solvent additives inspires us to further control the morphological features of the non-fullerene OPVs by fine-tuning the solvent-additive concentration beyond the globally accepted level. This was effective for optimizing the indoor PCE of non-fullerene OPVs (21.71%), which exceeded that of the conventionally accepted reference (18.02%). This study provides guidelines for understanding the critical roles of solvent additives and optimizing the morphology of non-fullerene BHJs for high-performance indoor OPV applications.

Dynamic Heat Transfer Characteristic of Heat Exchanger for Sensible Heat Recovery of Raw Coke Oven Gas

Abstract A simplified hybrid-dimensional unsteady heat transfer model for the ascension-pipe heat exchanger with a helically coiled tube embedded in the jacket and supported by high conductivity particles is established based on the non-thermal equilibrium theory of porous medium. This idea can also be used in the design of other heat exchange devices involving the helically coiled tube. According to calculations, the wall temperature of the ascension-pipe heat exchanger periodically varies due to the periodic variations of flow rate and temperature of raw coke oven gas. A great thermal stress will be produced due to this reason. The coal tar precipitation mainly occurs in the late stage of the coking period due to the continuous cooling of molten salt. Based on the detailed analysis, thermal conductivity of packing layer, heat capacity per unit volume of packing layer, volume of packing layer, flow rate of molten salt and inlet temperature of molten salt are important factors that should be scientifically designed in the design of this type of heat exchanger to reduce thermal stress and coal tar precipitation. Cutting off molten salt in the late stage of the coking period is an effective measure to control the wall temperature of the ascension pipe above the dew point of coal tar vapor.

Two-Dimensional Porphyrin-Based Covalent Organic Framework with Enlarged Inter-layer Spacing for Tunable Photocatalytic CO2 Reduction.

Two-dimensional (2D) porphyrin-based covalent organic frameworks (COFs) are one of the most promising candidates for photocatalytic carbon dioxide reduction reaction (CO2RR), which however still suffer from the hindered mass transfer during the catalysis procedure associated with the close packing of 2D COF layers due to the strong axial π-π stacking. Herein, condensation between the porphyrinic aldehydes p-MPor-CHO (M = H2, Co, and Ni) and 3,8-diamino-6-phenyl-phenanthridine (DPP) affords new porphyrin-based 2D COF architecture MPor-DPP-COFs (M = H2, Co, and Ni). The bulky phenyl substituent at the phenanthridine periphery of the linking unit reduces the axial π-π stacking, providing an enlarged inter-layer spacing of 6.0 Å according to high-resolution transmission electron microscopy. This, in combination with the large surface area (1021 m2 g-1) revealed by nitrogen sorption measurements at 77 K for CoPor-DPP-COF possessing electroactive Co ions, endows it with excellent photocatalytic activity for CO2RR with a CO generation rate of 10 200 μmol g-1 h-1 and a CO selectivity up to 82%. This work affords new ideas for achieving efficient photocatalytic CO2RR upon fine-tuning the inter-layer spacing of 2D COFs.

Thermal Enhanced Resistive Switching Performance of <100>‐oriented Perovskite [(TZ‐H)2(PbBr4)]n with High Working Temperature: a Triazolium/(PbBr4)n2n– Interfacial Interaction Insight

AbstractDespite the great progress has been made on device parameters and working mechanism of perovskite‐based memristors, thermal instability under extreme conditions limits their performance, and thermal effect on their resistive switching (RS) characteristics remains unclear. Herein, from the viewpoint of organic/inorganic interfacial interaction in a novel 2D <100>‐oriented perovskite [(TZ‐H)2(PbBr4)]n (TZ = 1H‐1,2,4‐triazole), thermal effect on the RS performance of perovskite‐based memristor is investigated. This FTO/[(TZ‐H)2(PbBr4)]n/Ag memristor can exhibit high thermal tolerance with a working temperature of 170 °C, and the best RS characteristics can be achieved at 140 °C. Mechanistic studies are executed based on X‐ray single structural analysis, powder X‐ray diffraction, UV–Vis, and fluorescence. Before the occurrence of phase change below 140 °C (α‐phase), anisotropic lattice expansion illustrated by the weaker inter‐layer NH···Br hydrogen bond, longer layer–layer distances, more distorted PbBr6 octrahedra, larger optical gap, and quenched fluorescence can be beneficial for the trap‐filled limited process. After phase transformation into β‐phase, the breakage of layer–layer interaction and looser layer–layer packing will inhibit the halogen migration, resulting in more space charge limited conduction characters. The unique thermal enhanced RS performance with status monitored by fluorescent chromism can provide a new paradigm for the development of new memristors with highly environmental tolerance.

Optical Efficiency Improvement of Chip-on-Board Design LEDs with TiO2/Silicone Packaging Coating

Since TiO2 nanoparticles and silicon composites include a strong scatter influence, they are well-known for improving scattered lighting in LED packets. To improve the optic quality of LEDs packaged with chip-on-board (COB), a thin layer made of high-concentration TiO2 and silicon glue is added to the primary packing layer. COB LEDs’ light extraction efficiency (LEE) rises up to 65% when the key encapsulation includes just silicone, according to the findings of experiments. As a coating of TiO2 and silicone is added, however, the increase in LEE is dependent on the TiO2 concentration. The LEE can be increased from 6% to 24% as the concentration of nanoparticles drops to 0.035 g/cm3. Furthermore, at a mean correlated color temperature (CCT) of around 8500 K, the TiO2/silicone compounds layer will assist in lowering the angular correlated color temperature (CCT) variance between 900 and 470 K within the -90° to 90° observing angle range.

Foam in Absorption Columns with Structured Packings – Part 2: Inhibition and Destruction

AbstractFoam in absorption and distillation processes is one of the main reasons for malfunctions in columns including higher pressure loss, lower throughput, and lower mass transfer rates leading to a reduction in the separation efficiency. This study evaluates different foam management solutions aiming at a foam‐reduced operation of columns with structured packings based on fundamental investigations. Firstly, the effect of spacers between structured packing layers is presented as a passive foam inhibition method. Secondly, the ability of acoustic waves at low frequencies around 50 s−1 (Hz) destructing existing foam in columns is analyzed and discussed. This method is able to reduce the pressure loss by –56 % and increase the corresponding F‐factor by +22 % in a DN300 column in continuous operation.

Brillouin Spectroscopy of Binary Phospholipid-Cholesterol Bilayers.

Multicomponent lipid bilayers are used as models for searching the origin of spatial heterogeneities in biomembranes called lipid rafts, implying the coexistence of domains of different phases and compositions within the lipid bilayer. The spatial organization of multicomponent lipid bilayers on a scale of a hundred nanometers remains unknown. Brillouin spectroscopy providing information about the acoustic phonons with the wavelength of several hundred nanometers has an unexplored potential for this problem. Here, we applied Brillouin spectroscopy for three binary bilayers composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC), and cholesterol. The Brillouin experiment for the oriented planar multibilayers was realized for two scattering geometries involving phonons for the lateral and normal directions of the propagation. The DPPC-DOPC mixtures known for the coexistence of the solid-ordered and liquid-disordered phases had bimodal Brillouin peaks, revealing the phase domains with sizes more than a hundred nanometers. Analysis of the Brillouin data for the binary mixtures concluded that the lateral phonons are preferable for testing the lateral homogeneity of the bilayers, while the phonons spreading across the bilayers are sensitive to the layered packing at the mesoscopic scale.

The enthralling effect of packing on the light emission of pyridazinone based luminophore: Crystallographic, electronic absorption and computational studies

The present study unfolds the synthesis and characterization of a new butylidine linked hetero dimer of pyridazinone (PNP). The crystal structure analysis of PNP reveals that it exhibited infinite 1D linear chains connected through C-H∙∙∙O interaction and interlayer connectivity was supported by the unconventional orthogonal dipolar interaction via nitro-aromatic (ONO2···π(C)Ar). These interactions are also described using DFT calculations and are potentially studied. Here we discuss the influence of crystal structure on the photophysical properties of a new solid state emitter containing brick layer packing. Furthermore, we conducted detailed exploration of the intermolecular interactions that maintain the crystal packing of the structure by employing the Hirshfeld surface analysis and its corresponding two-dimensional fingerprint plots revealing that the C-H∙∙∙O interaction mainly stabilized the crystal structure. Time-dependent density functional theory (TDDFT) studies and observed nitro aromatic interactions (ONO2∙∙∙(C)Ar) in the crystal helped to explain the electronic behaviour of PNP. The validity of the computations is supported by a good agreement between the estimated and experimental values of the excitation energy transfer. Furthermore, we conducted detailed research on the Hirshfeld surface analysis and the intermolecular interactions that stabilize the crystal packing using their corresponding two-dimensional fingerprint plot. Some standard thermodynamical parameters such as specific heat, entropy and free energy have also been computed. In addition to this, the variation of specific heat with temperature has been explored.

First-Principles Study of Electronic and Optical Properties of Tri-Layered van der Waals Heterostructures Based on Blue Phosphorus and Zinc Oxide

The creation of van der Waals heterostructures with tunable properties from various combinations of modern 2D materials is one of the promising tasks of nanoelectronics, focused on improving the parameters of electronic nanodevices. In this paper, using ab initio methods, we theoretically predict the existence of new three-layer van der Waals zinc oxide/blue phosphorus/zinc oxide (ZnO/BlueP/ZnO) heterostructure with AAA, ABA, ABC layer packing types. It is found that AAA-, ABA-, and ABC-stacked ZnO/BlueP/ZnO heterostructures are semiconductors with a gap of about 0.7 eV. The dynamic conductivity and absorption spectra are calculated in the wavelength range of 200–2000 nm. It is revealed that the BlueP monolayer makes the greatest contribution to the formation of the profiles the dynamic conductivity and absorption coefficient spectrums of the ZnO/BlueP/ZnO heterostructure. This is indicated by the fact that, for the ZnO/BlueP/ZnO heterostructure, conductivity anisotropy is observed at different directions of wave polarization, as for blue phosphorus. It has been established that the absorption maximum of the heterostructure falls in the middle ultraviolet range, and, starting from a wavelength of 700 nm, there is a complete absence of absorption. The type of layer packing has practically no effect on the regularities in the formation of the spectra of dynamic conductivity and the absorption coefficient, which is important from the point of view of their application in optoelectronics.

The Feasibility of Hydroxypropyl Methylcellulose as an Admixture for Porous Vegetarian Concrete Using Coarse Recycled Aggregates

In this paper, hydroxypropyl methylcellulose (HPMC) is used as a new additive for porous vegetarian concrete (PVC) to improve its void structure and strength. The effect of the HPMC on the fluidity of the mortar was first investigated by a viscosity test. Then the cement hydration process was determined for analyzing the effect of the HPMC on the strength and durability of the hardened PVC. Subsequently, experiments to investigate the mass transport and compressive strength characteristics, as well as the vegetarian properties, of the concrete were carried out. The results show that the bonding forces between the recycled aggregates and packing layer are elevated by viscosity improvement. The viscocity and flowability are significantly related to the dosage of HPMC from 0.0‰ to 0.3‰. The harden time is also delayed while the content of HPMC increases.The segregation phenomenon caused by the recycled aggregate powder in porous concrete could also be relieved by adding HPMC. The durability of PVC in the wetting–drying cyclic test is significantly improved by incorporating HPMC. The results of the vegetarian test also prove that, with HPMC mixing, sufficient space would be created in porous concrete, which is more suitable for plant growth due to a large number of existing pore channels.

In-situ construction of particle-accumulated hydrophobic packing layer from rigid polyurethane wastes for gas pre-dehydration

HypothesisRigid polyurethane, a common insulation material, is difficult to degrade naturally and poses significant health and environmental risk. Consequently, the cost-effective and efficient reuse of these solid wastes is a great challenge. ExperimentsHerein, we report an in-situ construction of hexadecyltrimethoxysilane (HDTMS) hydrophobic films on rigid polyurethane waste particle (RPUWP) as an accumulated packing layer in the gas-liquid pre-separator for gas pre-dehydration. FindingsThe RPUWP grafted with HDTMS (P-HDTMS) packing layer exhibits excellent hydrophobicity in the air, acid (pH = 1), alkali (pH = 14), and high-temperature (over 95 ℃) resistance. Also, the gas pre-dehydration performance of the accumulated P-HDTMS packing layer in the gas-liquid pre-separator was evaluated by the water dew point depression (ΔTd). It is worth mentioning that the accumulated packing layer can stabilize and greatly reduce the ΔTd by 17.8 ℃ in over 48-hour uninterrupted operation through the coalescence separation mechanism. Therefore, the low-cost accumulated P-HDTMS packing layer is expected to be an ideal candidate material for gas pre-dehydration in large-scale practical applications. This work not only provides a novel method for the resource utilization of plastic solid wastes but also provides a hitherto unexplored perspective for gas dehydration in industrial production.

Experimental Study on Stimulation of Horizontal Wells Filled with Film-Coated Gravel in Deep-Sea Bottom-Water Gas Reservoirs.

Large gas reservoirs such as Yacheng and Lingshen have been discovered in the exploration of deep-sea gas reservoirs in the South China Sea in recent years. However, the existence of bottom-water and sufficient water energy in deep-sea gas reservoirs seriously affects the development effect of gas reservoirs. In order to effectively control water development of deep-seabed water gas reservoirs, it is proposed to fill water-resistant and breathable coated gravel outside horizontal wells for mining. Based on the preparation of modified coated gravel, this paper studies the resistance of coated gravel to friction damage, temperature damage, acid damage, pressure damage, and water-resistant performance of coated gravel. The results show that (1) the coated gravel coating has good resistance to friction erosion and acidification corrosion. The upper limit of temperature resistance is 250°, and the pressure resistance is 90.4 MPa. (2) The water resistance of the film-coated gravel packing layer decreases with the increase of packing layer permeability. (3) The film-coated gravel pack can reduce the water-phase flow ability of reservoirs, delay the bottom water ridging speed, increase the waterless gas development time of gas wells, and improve the final recovery of bottom-water gas reservoirs. The coated gravel has permeability and water resistance properties and can be used to voluntarily select water plugging in the coated gravel pack. This technology can develop a new technical idea for water control of deep-seabed water gas reservoirs.

Phase tuning of P2/O3-type layered oxide cathode for sodium ion batteries via a simple Li/F co-doping route

• P2-LNMTCOF has higher sodium content due to the basis material with the component of O3-type cathode material. • The LiF additive can promote the formation of P2-type cathode material. • The LiF additive can realize the co-doping of anions and cations at the same time. • The voltage drop during cycling has been suppressed due to the more stable TM-O (F) octahedron. • The TOF-SIMS techniques provide novel and powerful tools for exploring the binding state between elements. Element doping is a common and effective method for improving the electrochemical performance of cathode materials, and typically it can be divided into cation ion and anion ion doping. Among the cathode materials of sodium-ion batteries, the important layered oxide cathodes mainly include those of O3 and P2 types, according to the sites of Na ions and the number of oxide layer packings. Hereon, the successful transformation of O3-type cathode NaNi 0.45 Mn 0.4 Ti 0.1 Co 0.05 O 2 (O3-NMTCO) into P2-type cathode of NaNi 0.45 Mn 0.4 Ti 0.1 Co 0.05 O 2 -0.08LiF (P2-LNMTCOF) is achieved via a facile Li/F co-doping route. The modified P2-type cathode (P2-LNMTCOF) have main three advantages over the traditional P2-type cathode Na 0.7 Ni 0.45 Mn 0.4 Ti 0.1 Co 0.05 O 2 (P2-NMTCO): higher Na content, solid solution reaction in high-voltage range, and stronger TM-F bond. As a result, the current P2-LNMTCOF cathode shows the best cycling performance, with the initial capacity of about 160 mA h g −1 and the capacity retention of 61% after 200 cycles. In addition, because of the more stable TM-O (F) octahedron, the voltage drop during cycling has been effectively suppressed. This study provides a new idea and reference for synthesizing high performance P2-type layered oxide cathode materials for sodium-ion batteries.

Alkali-Induced In Situ Formation of Amorphous NixFe1-x(OH)2 from a Linear [M3(COO)6]-Based MOF Template for Overall Electrochemical Water Splitting.

Amorphous and bifunctional electrocatalysts based on 3d transition metals tend to exhibit better performance than their crystalline counterparts and are a promising choice for efficient overall water splitting yet far from being well explored. A 3,6-net metal-organic framework (MOF) of [Ni3(bpt)2(DMF)2(H2O)2]·1.5DMF (Ni-MOF), based on linear [Ni3(COO)6] as a node and [1,1'-biphenyl]-3,4',5-tricarboxylic acid (H3bpt) as a linker, was conveniently prepared via a hydrothermal reaction. Benefitting from the wide compatibility of the octahedral coordination geometry in Ni-MOF for different 3d metal ions, the molecular level and controllable metal doping facilitates the production of the desired Ni/Fe bimetallic MOF. A high-concentration alkali solution of 1 M KOH induced the in situ transformation of the MOF as a precursor to new amorphous electrocatalysts of [Ni(OH)2(H2O)0.6]·H2O [a-Ni(OH)2] and its metal-doped derivatives of a-Ni0.77Fe0.23(OH)2 and a-Ni0.65Fe0.35(OH)2. In particular, the costly organic ligand H3bpt was fully dissolved in the alkaline solution and can be recovered for cyclic utilization by subsequent acidification. The obtained amorphous hydroxide was deduced to be loose and defective layers containing both coordinated and lattice water based on combined characterizations of TG, IR, Raman, XPS, and sorption analysis. As opposed to the crystalline counterpart of Ni(OH)2 with stacked packing layers and an absent lattice water, the abundant catalytic active sites of the amorphous electrocatalyst endow good performance in both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The bifunctional a-Ni0.65Fe0.35(OH)2 coated on nickel foam realizes small overpotentials of 247 and 99 mV for OER and HER, respectively, under a current density of 10 mA cm-2, which can work with a cell voltage of merely 1.60 V for overall water splitting. This study provides an efficient strategy for widely screening and preparing new functional amorphous materials for electrocatalytic application.