Polyoxometalate solution passivation enabling dendrite-free and high-performance zinc anodes in aqueous zinc-ion batteries.

Zinc metal anodes in aqueous electrolytes commonly face challenges such as dendrite growth and undesirable side reactions, limiting their application in the field of aqueous zinc-ion batteries (AZIBs) for energy storage. Drawing inspiration from industrial practices involving molybdenum salt solutions for metal modification, a polyoxometalate solution was formulated as a passivation solution for zinc anodes (referred to as MO solution). The formed passivation layer, referred to as the MO layer, exhibited a uniform and protective nature with a thickness of approximately 10 µm. The experimental results demonstrated that this passivation layer effectively suppressed side reactions at the zinc anode interface, as evidenced by lower corrosion current density for MO-Zn anodes. Additionally, the newly plated Zn was uniformly deposited atop the MO layer, ensuring coating integrity and inhibiting dendrite growth. As a result, under more demanding conditions such as a larger current of 8 mA cm-2, the MO-Zn anode displayed an extended cycle life exceeding 420 h in a symmetric battery, with an overpotential as low as 98 mV. This performance significantly outperformed that of commercially available pure Zn foils (with a cycle life of 60 h and an overpotential of 192 mV). Notably, a self-made Na-doped V2O5 served as the cathode (referred to as NaVO), forming the MO-Zn//NaVO full battery. Even under high current test conditions of 2 A/g, the specific capacity of the MO-Zn//NaVO full battery remained substantial at 152.83 mAh/g after 1000 cycles. Furthermore, pouch batteries assembled with NaVO//MO-Zn successfully illuminated small bulbs. This study offers a viable optimization strategy for AZIB anodes and demonstrates the potential of using polyoxometalate solution for etching zinc anodes to inhibit dendrite growth and interfacial corrosion of zinc metal anodes.

A MOF-derived flower-shaped CeCo-oxide as a multifunctional material for high-performance lithium-ion batteries and supercapacitors.

Precursor method is a well-known technology for preparing certain functional materials. In this work, a novel 3d-4f bimetallic organic framework, denoted as 45MCeCo (45 M representing 4,5-imidazole dicarboxylic acid), was successfully synthesized via a hydrothermal technique. The compound thus obtained has the molecular formula of C10H11CeCoN4O12. By meticulously controlling the amounts of the experimental materials, it was feasible to prepare flower-like crystals possessing identical single crystal structures and significantly larger specific surface areas. As a precursor for electrode materials, this structure underwent calcination at different temperatures to prepare Co3O4/CeO2 composites with in situ composite heterostructures. Post-electrochemical tests revealed that CeO2 remains unreactive across all potentials, thereby contributing to the stabilization of the electrode material structure. In contrast, Co3O4 participated in redox reactions to provide a specific capacity to the sample. In addition, when comparing the performance of the electrode material under different calcination conditions, it became evident that the material exhibited optimal electrochemical performance when subjected to a temperature of 700 °C for 2 h.

Printing 3D mesh-like grooves on zinc surface to enhance the stability of aqueous zinc ion batteries.

Aqueous zinc ion batteries (AZIBs) are receiving broad attention owing to their high safety and low cost. However, the high mechanical strength and irreversible growth of zinc dendrites limit the practical application of AZIBs. Herein, regular mesh-like gullies are built on the surface of zinc foil (M150 Zn) by using simple model pressing method and stainless steel mesh as a mold. Due to the charge-enrichment effect, zinc ion deposition and stripping will be preferentially carried out in the grooves to keep the outer surface flat. In addition, zinc is exposed to 002 crystal surface in the gully after being pressed, and the deposited zinc is more inclined to grow at a small angle, so that it has a sedimentary morphology parallel to the basement. Consequently, at a current density of 0.5 mA cm-2, the M150 zinc anode has a voltage hysteresis of only 35 mV and a cycle life of up to 400 h (relative to a zinc foil of 96 mV and 160 h). Even more imposing is that the full cell has a capacity retention of approximately 100% after 1000 cycles at 2 A g-1 and a specific capacity of almost 60 mAh g-1 when activated carbon is used as the cathode. It is a promising method to improve the stable cycle performance of AZIBs by using a simple method to realize the non-prominent dendrites on the surface of zinc electrode.

Nitrogen-rich Graphite Flake from Hemp as Anode Material for High Performance Lithium-ion Batteries.

Biomass-derived carbon (BC) has attracted extensive attention as anode material for lithium ion batteries (LiBs) due to its natural hierarchical porous structure and rich heteroatoms that can adsorb Li+ . However, the specific surface area of pure biomass carbon is generally small, so we can help NH3 and inorganic acid produced by urea decomposition to strip biomass, improve its specific surface area and enrich nitrogen elements. The nitrogen-rich graphite flake obtained by the above treatment of hemp is named NGF. The product that has a high nitrogen content of 10.12% has a high specific surface area of 1151.1 m2 g-1 . In the lithium ion battery test, the capacity of NGF is 806.6 mAh g-1 at 30 mA g-1 , which is twice than that of BC. NGF also showed excellent performance that is 429.2 mAh g-1 under high current testing at 2000 mA g-1 . The reaction process kinetics is analyzed and we found that the outstanding rate performance is attributed to the large-scale capacitance control. In addition, the results of the constant current intermittent titration test indicate that the diffusion coefficient of NGF is greater than that of BC. This work proposes a simple method of nitrogen-rich activated carbon, which has a significantly commercial prospect.

UV-derived double crosslinked PEO-based solid polymer electrolyte for room temperature.

The low ionic conductivity at room temperature and poor dimensional stability at high temperature of polyethylene oxide (PEO)-based solid electrolytes greatly limit the development and utilization of solid polymer electrolytes (SPEs). To reconcile the contradiction between electrochemical performance and mechanical strength of PEO-based SPEs, a cross-linking structure with active -CH2CH2O- soft chains that doped with rigid segments is designed and prepared through a method of green ultraviolet irradiation without solvent. The obtained solid film shows a high ionic conductivity of 0.2 mS·cm-1 and an ionic transference number of 0.51 at room temperature. The activation energy value of 1.92 kJ·mol-1 gives evidence for a favorable migration mechanism of PTP-SPE. A combination of flexibility and strength can be realized by molecular structure design with a tensile elongation of 40%. The reversible overpotential in galvanostatic cycling over 500 h of a Li||Li symmetrical cell indicates that the compact PTP-SPE can inhibit the formation of lithium dendrites. This work provides a new strategy for designing high-performance composite solid electrolytes at room temperature.

A dual strategy for synthesizing crystal plane/defect co-modified BiOCl microsphere and photodegradation mechanism insights.

Because of different atomic arrangements and/or different exposed atoms on different surfaces of crystalline particles, different physical and chemical properties can be resulted and exhibited. In this work, we prepared BiOCl with {110} crystal facet by introducing urea as the structure-directing agent, and constructed oxygen vacancies (OVs) in BiOCl (110) to form BiOCl (110)-OV. Control of exposure surface can improve photocatalyst activity and the defect level caused by OVs can improve charge separation and light absorption, thereby further enhancing the production of free radicals and the activation of pollutants. Due to the synergistic effect of the hierarchical microsphere structure of BiOCl and OVs, the degradation rate of tetracycline hydrochloride (20 mg/L) in the presence of BiOCl (110)-OV can reach 95.1% after 15 min of the simulated sunlight illumination. This research provides novel ideas for the design and development of photocatalyst with hierarchical structure and oxygen vacancy defects.

Design of Z-scheme g-C3N4/BC/Bi25FeO40 photocatalyst with unique electron transfer channels for efficient degradation of tetracycline hydrochloride waste.

High electron transfer rates and a higher number of electron transfer active sites play important roles in inhibiting the recombination of photogenerated electron-hole pairs. In the experiments described in this article, the g-C3N4/BC/Bi25FeO40 composite material was prepared to use biochar (BC) as the conductive channel. The presence of BC significantly increases the electron transfer rate due to its excellent electrical conductivity and can provide more electron transfer active sites. At the same time, BC provides a larger surface area and has a loose porous structure, which lead to excellent adsorption performance. Based on various characterization results, it was confirmed that the Z-scheme heterojunction was successfully constructed between g-C3N4 and Bi25FeO40. The photocatalytic experiment results showed that the degradation efficiency of g-C3N4/BC/Bi25FeO40 on the tetracycline hydrochloride (TCH) could reach 92.2% within 60 min. Parameters such as circulation stability, pH value of the solution and the amount of composite materials were studied. The synthesized composite material has good reusability and high efficiency in a wide pH range of 3-11. Its excellent photocatalytic activity is attributed to the formation of an effective Z-scheme heterostructure, as well as the rapid photoelectron transfer and excellent adsorption capacity of BC. This work provides a way to design new photocatalysts using semiconductor composite materials and BC materials.

High-performance ZnCo2O4 microsheets as an anode for lithium-ion batteries.

Mesoporous ZnCo2O4 microsheets are successfully obtained by using a MOF as a precursor. Benefiting from the special structure with favorable electron-transfer and Li-ion diffusion properties, the sample calcined at 600 °C exhibits superior lithium storage capacity of 816.2 mA h g-1 at 100 mA g-1 after 100 cycles, which has great application potential.

Highly efficient Co3O4/CeO2 heterostructure as anode for lithium-ion batteries.

Co3O4 has been extensively studied as an anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity. However, during the charging-discharging processes, the issues of large volume change and low electric conductivity arise, which significantly limit the practical applications of Co3O4. To solve these issues, a Co3O4/CeO2 heterostructure derived from metal-organic frameworks (MOFs) was designed and synthesized through one-step microwave synthesis. Benefiting from the mesoporous structure and presence of hetero-components, Co3O4/CeO2 having the molar ratio of Co/Ce = 5:1 (denoted as 5Co3O4/CeO2) exhibits high reversible capacity and excellent cycling stability when used as an anode material for LIBs. Specifically, compared to a single-phase Co3O4 anode, which shows a capacity of 538.6 mAh/g after 100 cycles, 5Co3O4/CeO2 exhibits a higher capacity (1131.2 mAh/g at 100 mA/g). This study provides a novel strategy for using rare earth components to modify electrode materials.

Lithium-Lanthanide Bimetallic Metal-Organic Frameworks towards Negative Electrode Materials for Lithium-Ion Batteries.

Novel lithium-lanthanide (Ln: cerium and praseodymium) bimetallic coordination polymers with formulas C10 H2 LnLiO8 (Ln: Ce (CeLipma) and Pr (PrLipma)) and C10 H3 CeO8 (Cepma) were prepared through a simple hydrothermal method. The three compounds were characterized by means of FTIR spectroscopy, X-ray diffraction, single-crystal X-ray diffraction, SEM, TEM, and X-ray photoelectron spectroscopy. The results of structural refinement show that they belong to triclinic symmetry and P 1 ‾ space group with cerium (or praseodymium) and lithium cations, forming coordination bonds to oxygen atoms from different pyromellitic acid molecules, and leading to the construction of 3D structures. It is interesting to note that the frameworks exclude any coordination water and lattice water. As an electrode material for lithium-ion batteries, CeLipma exhibits a maximum capacity of 800.5 mAh g-1 and a retention of 91.4 % after 50 cycles at a current density of 100 mA g-1 . The favorable electrochemical properties of the lanthanide coordination polymers show potential application prospects in the field of electrode materials.

Facile Synthesis and Optical Properties of Aluminum Nitride Nanowires Array.

AlN nanowires macro-array were successfully fabricated on Si substrate by double template method and chemical vapour deposition. The research shows that AlN nanowires array with different diameter, length and coverage can be prepared by controlling the experimental conditions. The as-prepared AlN nanowires array were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, the Ultraviolet absorption of AlN nanowires array as a sensors was investigated and calculated with the first principle.

Core-shell structured Co@CN nanocomposites as highly efficient dual function catalysts for reduction of toxic contaminants and hydrogen evolution reaction.

In this study, we have reported nitrogen-doped graphite C coated Co nanocomposite (Co@CN) catalysts synthesized by one-step arc discharge method. The surface compositions, morphologies and the catalytic properties of the Co@CN nanocomposites were studied minutely. The results reveal that the prepared Co@CN nanocomposites have typical core-shell structure and show highly efficient catalytic performance in a reduction of 4-nitrophenol (4-NP), rhodamine and methylene blue. Their rate constant (Kapp) is 0.074 s-1 in a reduction of 4-NP, which is much higher than that of reported transition metal-based catalysts. Moreover, the overpotential of Co@CN is only 96 mV at a current density of 10 mA cm-2 in alkaline solution, showing high electrocatalytic activities in the hydrogen evolution reaction. The excellent synergistic effect between nitrogen-doped graphite C shell and magnetic Co core enables the Co@CN nanocomposites catalysts to hold abundant active sites and to transmit rapidly electron ability, resulting in Co@CN nanocomposite catalysts having a highly efficient catalytic nature.

Oxygen vacancy rich Cu2O based composite material with nitrogen doped carbon as matrix for photocatalytic H2 production and organic pollutant removal.

A nitrogen doped carbon matrix supported Cu2O composite material (Cu/Cu2O@NC) was fabricated successfully with a coordination polymer as precursor through calcination. In this composite material, Cu2O particles with a size of about 6-10 nm were dispersed evenly in the nitrogen doped carbon matrix. After calcination, some coordinated nitrogen atoms were doped in the lattice of Cu2O and replace oxygen atoms, thus generating a large number of oxygen vacancies. In Cu/Cu2O@NC, the existence of oxygen vacancies has been confirmed by electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS). Under visible light irradiation, Cu/Cu2O@NC exhibits excellent H2 production with the rate of 379.6 µmol h-1 g-1. Its photocatalytic activity affects organic dyes, such as Rhodamine B (RhB) and methyl orange (MO). In addition to photocatalysis, Cu/Cu2O@NC also exhibits striking catalytic activity in reductive conversion of 4-nitrophenol to 4-aminophenol with in presence of sodium borohydride (NaBH4). The conversion efficiency reaches almost 100% in 250 s with the quantity of Cu/Cu2O@NC as low as 5 mg. The outstanding H2 production and organic pollutants removal are attributed to the oxygen vacancy. We expect that Cu/Cu2O@NC will find its way as a new resource for hydrogen energy as well as a promising material in water purification.

Decomposition of MOFs for the preparation of nanoporous Co3O4 fibres and sheets with excellent microwave absorption and photocatalytic properties.

Unique nanoporous Co3O4 fibres and sheets were successfully fabricated via a facile hydrothermal route (150 °C) and subsequent annealing process at 500 °C in air. The excellent microwave absorption of the nanoporous Co3O4 materials originates not only from the dielectric loss and impedance matching, but also from geometrical effects. Herein, the photocatalytic behavior of the as-prepared Co3O4 has also been reported based on the degradation of methylene blue (MB) dye in an aqueous medium under simulated solar light.

Zeolite CAN and AFI-Type Zeolitic Imidazolate Frameworks with Large 12-Membered Ring Pore Openings Synthesized Using Bulky Amides as Structure-Directing Agents.

Using bulky amides as the structure-directing agents (SDAs) is an alternative synthetic strategy for the exploration of crystalline large pore (≥12-membered ring) zeolitic imidazolate frameworks (ZIFs). Specifically, by using the bulky amides, dibutylformamide (DBF) and dipropylformamide (DPF) as solvent and imidazole (Im) as a ligand, two ZIFs mimicking the CAN and AlPO-5 (AFI) zeotypes with 12-membered ring (MR) pore openings were synthesized, and denoted as CAN-[Zn(Im)2] and AFI-[Zn(Im)2], respectively. These two materials are the first known examples of Zn(Im)2 polymorphs with 12-MR pores and AFI-[Zn(Im)2] has the largest pore apertures reported to date for ZIF materials. The concept that the bulky amides used were not simply acting as the solvent, but were in fact acting as SDAs or templates during the synthesis of the large pore ZIFs, was suggested by the closeness of the geometrical fit between the guest DBF and the can cages (composite building units) of the CAN-[Zn(Im)2].

Cobalt and copper pyridylmethylphosphonates with two- and three-dimensional structures and field-induced magnetic transitions.

Two novel metal pyridylmethylphosphonates, namely, [Co(4-pmp)] (1) and [Cu(4-pmp)(H2O)] (2), (4-pmpH2 = 4-pyridylmethylphosphonic acid), have been hydrothermally synthesized and characterized by X-ray diffraction, infrared spectroscopy, elemental analysis, and thermogravimetric analysis. In compound 1, each {PO3C} tetrahedron is corner-shared with three {CoNO3} tetrahedra and vice versa, thus forming a one-dimensional (1-D) inorganic chain along the a axis containing 8-membered rings of [(Co-O-P-O)2]. The inorganic chains are further connected by a 4-pmp(2-) ligand, generating a 2-D layered structure. Compound 2 displays a three-dimensional (3-D) framework structure, in which the inorganic layers are pillared by the pyridyl groups of the ligand, generating a 3-D pillared-layered structure. The magnetic properties of 1 and 2 have been studied. Compounds 1 and 2 behave as metamagnets at low temperature. The critical fields are about 70 kOe for 1 and 47 kOe for 2 at 1.8 K.

Calcium Phosphonate Frameworks for Treating Bone Tissue Disorders.

Two new examples of uncommon three-dimensional Ca-bearing metal organic frameworks, [Ca(H2O)3(HPXBP)] (CaP1) and [Ca2(H2O)2(HPXBP)1.5] (CaP2) (PXBP: p-xylylenebisphosphonate), were prepared and their structures characterized by single crystal X-ray diffraction. CaP1 crystallizes in the monoclinic C2/c space group, with three water molecules occupying a half coordination sphere on one side of the Ca atom, while CaP2 crystallizes in the triclinic P1̅ space group, with two crystallographic unique Ca atoms, each coordinated by a single water molecule. In contrast with CaP2, which exhibits very low bioactivity, CaP1 readily precipitates bone-precursor phases (octacalcium phosphate, OCP, and hydroxyapatite) in SBF solutions. Moreover, studies with MG63 osteoblast-like cells indicate that CaP1 is not toxic and stimulates bone mineralization and, thus, holds considerable potential for treating bone diseases, such as osteoporosis.

Ionothermal synthesis, crystal structure, topology and catalytic properties of heterometallic coordination polymers constructed from N-(phosphonomethyl) iminodiacetic acid.

Reactions of rare earth chlorides, N-(phosphonomethyl)iminodiacetic acid (H(4)pmida) and ferrous oxalate dihydrate under ionothermal conditions result in four new isostructural 3d-4f heterometal coordination polymers, [LnFe(III)Fe(6)(Hpmida)(6)]·2H(2)O {Ln = Eu (1), Dy (2), Ho (3) and Y (4)}. All compounds were characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and X-ray diffraction. The compounds feature a very interesting three dimensional (3-D) structure built up from a secondary building unit, [Fe(2)(Hpmida)(2)](2-) and possess a new topology type and complicated unique tilings. The catalytic properties of compounds 1-4 were investigated showing that these types of compounds are heterogeneous catalysts in the Knöevenagel condensation with high selectivity.

First principles simulation of temperature dependent electronic transition of FM-AFM phase BFO.

Understanding how temperature affects the electronic transitions of BFO is important for design of BiFeO3 (BFO)-based temperature-sensitive device. Hitherto, however, there have been only very limited reports of the quantitative simulation. Here, we used density functional theory (DFT) and two-dimensional correlation analysis (2D-CA) techniques to calculate the systematic variations in electronic transitions of BFO crystal, over a range of temperature (50~1500 K). The results suggest that the heat accumulation accelerates the O-2p(4) orbital splitting, inducing the Fe(3+)-3d(5) → Fe(2+)-3d(5)d(0) charge disproportionation. The origin is observed as the temperature-dependent electron transfer process changes from threefold degeneracy to twofold degeneracy. Additionally, the crystallographic orientation (111) can be used to control the 2p-hole-induced electronic transition as O → unoccupied Fe(3+)-3d(5), in comparison to the O → Bi-6p(3) + Fe(3+)-3d(5)d(0) on the orientations (001) and (101). This study offers new perspective on the improvement of BFO-based temperature-sensitive device.

Zn10(Im)20·4DBF: an unprecedented 10-nodal zeolitic topology with a 10-MR channel and 10 crystallographically independent Zn atoms.

By using a large-size amide, dibutylformamide (DBF), as a structure directing agent, a new zeolitic imidazolate framework (ZIF) was synthesized. The ZIF Zn10(Im)20·4DBF has an unprecedented zeolitic topology and features 10 crystallographically independent Zn atoms, a 10-membered ring (MR) channel and an unusual 4-connected 10-nodal net.