Fluorine Ions Research Articles

KOH modification of fluorinated graphite and its reaction mechanism

KOH electrochemical method and heating method were employed to modify fluorinated graphite and explore the modification mechanism. The chemical composition and microstructure of the products were characterized and analyzed before and after the reaction. As the electrochemical reaction time or heating temperature increased, the carbon fluorine bond gradually underwent a nucleophilic reaction with KOH according to its reactivity, promoting the formation of fluorine ions in the residual product and carbon oxygen bonds in the corresponding oxidized fluorinated graphite (OFG). The electrochemical method with the anode on the bottom and the heating method were insufficient to allow the isolated carbon fluorine bond to react, retaining some carbon fluorine bonds. By positioning the anode on top, electron transfer significantly accelerates the activation of the carbon fluorine bond, which then reacts completely. According to theoretical simulation calculations, electronegative groups around the carbon fluorine bond can effectively enhance its reactivity.

Synthesis and characterization of red-emitting Yb/Ho-CaSiO3 upconversion phosphors

Host material plays an important role in obtaining efficient photon upconversion and downshifting luminescence. Generally, fluoride and oxyfluoride glasses-based materials are used for high-efficiency photon upconversion. However, the poor thermal stability of fluoride glasses and the toxicity of fluorine ions limit their applications. In this report, Yb/Ho-doped CaSiO3 wollastonite phosphors have been demonstrated as efficient red-emitting upconversion phosphors. The phosphors have been synthesized by microwave hydrothermal process followed by heat treatment at 1050 ​°C in the air environment. 2M phase of the β-wollastonite has been confirmed by X-ray diffraction and Raman spectroscopy while the existence of the Yb and Ho dopants in the CaSiO3 lattice has been confirmed by X-ray photoelectron spectroscopy. The synthesized samples showed strong red upconversion emission centered at 662 ​nm and near-infrared downshifting emissions at 2016 ​nm upon 980 ​nm excitation. The emissions were found to depend significantly on the Ho concentration. Temporal evolution of the main emission bands was investigated to show that the energy transfer upconversion from Yb to Ho ions was responsible for the efficient upconversion and downshifting phenomenon.

Reinforced adsorption mechanism of fluorine ions by calcium-depleted hydroxyapatite and application in the raffinate from the vanadium industry

Calcium-deficient hydroxyapatite (Ca-d HAP), an adsorbent of high defluoridation capacity with lattice defect, was prepared from vanadium industrial waste neutralization slag (NS). The adsorption performance was compared to commercially available stoichiometric HAP (S-HAP) under different solution conditions, and Ca-d HAP was superior to S-HAP. The specific surface area of Ca-d HAP was considerable (118.32 m2/g), which was 3.176 times larger than that of S-HAP (37.25 m2/g), and this was the main reason for the strong adsorption performance of Ca-d HAP. Meanwhile, due to the presence of minor impurities, such as Al and Fe, in NS, the doping of Al and Fe reduced the crystallinity after Ca-d HAP synthesis, which provided additional active sites for binding to other ions. In addition, combined with characterization analysis, it was speculated that some Ca ions in Ca-d HAP were replaced by Na ions with stronger ion-exchange properties, enhancing its adsorption performance. The adsorption mechanism of Ca-d HAP on F- ions was further investigated by discussing the surface potential, initial pH, adsorbent dosage, initial fluorine concentration, adsorption thermodynamics, and kinetics. Results showed that the Langmuir isothermal model well predicts the adsorption behavior of Ca-d HAP on F- ions at pH 3.5, with a maximum adsorption capacity of 277.78 mg/g, which is larger than most HAP adsorbents reported in the literature. In addition, the percentage adsorption of Ca-d HAP on F- ions was > 99 % in the raffinate and the NaF solution. In addition, the percentage adsorption of Ca-d HAP on F- ions was > 99 % both in the raffinate and in the NaF solution. The adsorption of F- ions by Ca-d HAP is a heat absorption process, with the ΔG° < 0 at various temperatures, demonstrating the reaction's spontaneity of the reaction. The pseudo-second-order model better described the adsorption kinetics data at 303 to 333 K, and the adsorption was regulated by chemical reactions. Overall, Ca-d HAP with lattice defects has a large ion-exchange rate and specific surface area, which is the key reason for the high adsorption performance of Ca-d HAP. Therefore, this technology provides a prospect for treating acidic wastewater with high fluorine content in the vanadium industry.

Fluorine-doped nickel-copper layered double hydroxide combined with nitrogen-doped reduced graphene oxide for high-performance asymmetric supercapacitor

An asymmetric supercapacitor (ASC) is proposed by employing fluorine-doped NiCu layered double hydroxide (Ni4CuLDH/F) cathode and nitrogen-doped reduced graphene oxide (N-rGO) anode. The Ni4CuLDH/F obtained a substantially dispersed structure and multiple active sites after fluorine ion doping, while the N-rGO achieved crimped graphene layers and additional pseudocapacitive properties after nitrogen doping. The Ni4CuLDH/F prepared by a low-temperature titration method displayed a considerable specific capacitance of 1780 F g−1 at a current density of 1 A g−1. Also, the capacitance of the hydrothermally prepared N-rGO intensified from 287 F g−1 to 392 F g−1 at 1 A g−1 with a wider potential window. Besides, an ASC based on the two electrodes presented an outstanding energy density of 54.0 Wh kg−1 at a power density of 375 W kg−1 with distinguished cycling capability (59% retention over 10000 cycles). Overall, the ASC reveals a tremendous possibility for practical implementation in the arena of high-performance supercapacitors.

Correlation with the Microstructure and Synergistic Physiochemical Etching Resistance of Nanocomposites under Fluorine-Containing Plasma Conditions.

In the semiconductor fabrication industry, high-power plasma is indispensable to obtain a high aspect ratio of chips. For applications to ceramic components including the dielectric window and ring in the semiconductor etching chamber, the Y2O3 ceramics have attracted interest recently based on excellent erosion resistance. When a high bias voltage is applied in a plasma environment containing fluorine gas, both chemical etching and ion bombardment act simultaneously on the ceramic components. During this etching process, severe erosion and particles generated on the ceramic surface can have effects on overall equipment effectiveness. Herein, we report the outstanding plasma etching resistance of Y2O3-MgO nanocomposite ceramics under a CF4/Ar/O2 gas atmosphere; the erosion depth of this material is 40-79% of that of the reference materials, Y2O3 ceramics. In a robust approach involving effective control of the microstructure with different initial particles and sintering conditions, it is possible to understand the relationship between etching behavior and microstructure evolution of the nanocomposite ceramic. The results indicate that the nanocomposite with fine and homogeneous domain distribution can decrease particle generation and ameliorate its life cycle; accordingly, this is a promising alternative candidate material for ceramic components in plasma chambers.

Selective acetone gas sensing of Cu2(OH)3F/CuO enhanced by hydroxy bonds and fluorine substitution

Acetone gas in human breath could be examined in terms of biomarker applications for diagnosis of diabetes and detection of body fat decomposition. In this work, Cu2(OH)3F is hydrothermally synthesized and then pre-annealed in the interest of low ppm acetone gas-sensing. Cu2(OH)3F/CuO hierarchical structures were built after pre-annealing, and 250°C-annealed samples show the highest response of 23.6 toward 10 ppm acetone gas and 2.1 toward 400 ppb at operating temperature 200 ℃. Upon characterization for Cu2(OH)3F/CuO material properties, 250 ℃-annealed nanobranches show fluent hydroxy bonds, fluorine ion substitutions, and wide bandgap which could enhance the gas-sensing characteristics. The pre-annealing of Cu2(OH)3F between 200 ℃ and 350 ℃ was thoroughly characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), elemental analysis (EA) and thermal gravitational analysis (TGA) to analyze mechanism of the acetone gas-sensing behaviors.

Evolution of dynamics of physico-chemical and mechanical properties of hydroxyapatite with fluorine addition and degradation stability of new matrices

This multidisciplinary study examined sensitively the change in the dynamics of main mechanical performance, stability of crystal structure, crystallinity quality, strength, corrosion resistance, biocompatibility, resistance to structural degradation/separations and mechanical durability features of hydroxyapatite (HAp) biomedical materials based on the fluorine addition and degradation process to guide future medical and dental treatment studies. In the study, the fluorine ions were used to be the dental coating, filling and supporting material for biologically or synthetically produced bone minerals. The general characteristic properties were investigated by means of standard spectroscopic, structural and mechanical analysis methods including RAMAN, SEM-EDS, TEM, Vickers micro-indentation hardness and density measurements. A time dependent release test was performed to evaluate possible fluorine ion release after the degradation process. It was found that the fundamental characteristic properties of HAp biomedical materials are noted to improve with the increase in the fluoride level up to 2% due much more stabilization of HAp crystal system. The combination of RAMAN spectra and powder XRD analyzes indicates that 2% addition level affects positively the formation velocity of characteristic HAP phase. Besides, fluorine doped HAp materials all exhibited the main characteristic peaks after degradation process. This is attributed to the fact that the fluorine ions enabled the hydroxyapatite to enhance the structural quality and stability towards the corrosion environment. However, in case of excess dopant level of 3% the degradation rates were obtained to increase due to higher contribution rate and especially electrostatic interactions. As for the surface morphology examinations, 2% fluorine added HAp with the highest density of 3.0879 g/cm3 was determined to present the superior crystallinity quality (smallest grain size, best smooth surface, honeycomb pattern, regular shaped particles and densest particle distributions through the specimen surface). Conversely, the excess fluorine triggered to increase seriously degree of micro/macro porosity in the surface morphology and microscopic structural problems in the crystal system. Thus, the HAp doped with 3% was the most affected material from the degradation process. Additionally, the fluorine ion values read after the release process were quite far from the value that could cause toxic effects. Lastly, the optimum fluorine addition provides the positive effects on the highest durability, stiffness and mechanical fracture strength properties as a consequence of differentiation in the surface residual compressive stress regions (lattice strain fields), amplification sites and active operable slip systems in the matrix. Hence, the crack propagations prefer to proceed in the transcrystalline regions rather than the intergranular parts. Similarly, it was found that Vickers micro-indentation hardness tests showed that the microhardness parameters increased after the degradation process. All in all, the fluorine addition level of 2% was noted to be good choice to improve the fundamental characteristic properties of hydroxyapatite biomedical materials for heavy-duty musculoskeletal, orthopedic implant, biological and therapeutic applications in medicine and dentistry application fields.

Preparation of nano-polyhedral-oligomeric-silsesquioxane-sol based on aggregation induced emission effect and research on fluoride ion identification mechanism

Fluoride plays an indispensable role in physiological process, it is widely used in the fields of toothpaste and medicine, etc. However, excess fluoride ions can cause acute gastritis, malignant skeletal fluorosis and kidney problems. Consequently, the accurate identification of fluoride is of great importance. Therefore, we functionalized octa (aminopropyl) polyhedral oligomeric silsesquioxane (OAP-POSS) (T8) with traditional aggregation caused quenching (ACQ) aromatic luminogens to obtain phthalic-anhydride-OAP-POSS (PAOP), which not only solves the problem of ACQ, but also can be used to identify fluorine ions. The identification limit was 1.27 × 10-5 mol/L in THF(tetrahydrofuran) and 5.86 × 10-4 mol/L in DMSO (dimethyl sulfoxide). Moreover, through theoretical calculation (DFT and TD-DFT) and experiment, we further studied the action mechanism of fluorine on silicon and explored the possibility of F- encapsulated in POSS cage.

A residue reutilization strategy on fluorine-containing water purification

The comprehensive utilization of coal gangue is a severe problem that many countries and regions confront. Extracting strategic metals from coal gangue and adequately treating the residue constitute a possible complete utilization route of coal gangue. This paper studied the structural characteristics and surface properties of ammonium salt roasting-water leaching residue by XRD, BET, XPS, FTIR, and XRF. The adsorption behaviour of leaching residue for fluorine ions was studied using batch adsorption tests, isothermal models, and fluoride removal tests of mine water. The results show that the leaching residue had a fast adsorption speed (1 min), a wide applicable pH range (4–11), and a wide applicable temperature range (25 °C–50 °C). The removal rate of fluorine in high-concentration (50 mg/L) and low-concentration (5 mg/L) fluorine-containing water reached more than 50%. The primary adsorption mechanism was ion exchange between fluorine ions and Al–OH in the leaching residue. The actual mine water test showed that the leaching residue did not introduce organic pollutants and accelerated the settlement of mine water. This study puts forward a new and environmentally friendly avenue for residue reutilization, which is of positive significance to promoting the comprehensive utilization of coal gangue.

Effect of Fluoride on the Expression of 8-Hydroxy-2'-Deoxyguanosine in the Blood, Kidney, Liver, and Brain of Rats.

Excessive exposure of fluoride not only leads to damage on bone, but also has an adverse effect on soft tissues. Oxidative DNA damage induced by fluoride is thought to be one of the toxic mechanisms of fluoride effect. However, the dose-response of fluoride on oxidative DNA damage is barely studied in organisms. This study investigated the concentration of fluoride in rat blood, kidney, liver, and brain as well as the dose-time effect of fluoride on the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the above tissues. Rats were exposed to 0mg/L, 25mg/L, 50mg/L, and 100mg/L of fluorine ion and treated for one and three months. The results showed that the accumulation of fluoride in soft tissues was very different. At the first month, blood fluoride was increased, liver and brain fluoride showed a U-shaped change, and kidney fluoride was not significant. At the third month, blood fluoride was altered with an inverted U-shaped change, kidney and brain fluoride increased, but liver fluoride decreased. Both the exposure concentration and the time of exposure had a significant effect on the expression of 8-OHdG in the above tissues. However, the effect patterns of fluoride on these tissues were notably different at different times. At the first month of fluoride treatment, blood, kidney, and liver 8-OHdG decreased with the increasing fluoride concentration. At the third month, blood 8-OHdG showed a U-shaped change, but kidney 8-OHdG altered with an inverted U-shaped change. Liver 8-OHdG increased, while brain 8-OHdG decreased at the third month. Correlation analysis showed that only blood 8-OHdG was significantly inversely correlated with blood fluoride and dental fluorosis grade in both the first and third months. Liver 8-OHdG was negatively and significantly correlated with liver fluoride. There was a weak but nonsignificant correlation between kidney and brain 8-OHdG and fluoride in both tissues. Additionally, blood 8-OHdG was positively correlated with kidney and liver 8-OHdG at the first month and positively correlated with brain 8-OHdG at the third month. Taken together, our data suggests that concentration and time of fluoride exposure had a significant effect on 8-OHdG, but the effect patterns of fluoride on 8-OHdG were different in the tissues, which suggests that the impact of fluoride on 8-OHdG may be a tissue-specific, as well as a non-monotonic positive correlation.

Activation of peroxymonosulfate via a novel UV/hydrated Fe(III) oxide coupling strategy for norfloxacin removal: Performance and mechanism

Advanced oxidation processes (AOPs) have been successfully applied for the degradation of fluoroquinolones, but most studies ignored the removal of fluorine ions (F−) generated after the degradation, and the remaining F− would cause secondary pollution to the water body. In this study, a novel UV radiation/hydrated Fe(III) oxide (HFO) coupling strategy was utilized to activate peroxymonosulfate (PMS) for the comprehensive enhanced removal of norfloxacin (NX) and the generated F−. Results showed that UV/HFO/PMS process significantly improved NX degradation efficiency compared with individual system, and NX degradation efficiency of 97.3% could be achieved by reactive oxygen species (ROS) generated in the process, in which singlet oxygen (1O2) was the main ROS. Moreover, the remaining concentration of F− was generally below 0.35 mg/L within a wide pH range (4–10). And the simultaneous adsorption of HFO for F− is mainly related to coordination and electrostatic interaction. After five cycles, the catalytic efficiency of HFO for NX removal only dropped by 4.4%. Besides, UV/HFO/PMS system had great anti-interference ability on coexisting anions. UV/vis two-dimensional correlation spectroscopy (2DCOS) analysis revealed that ROS would preferentially degrade the piperazine ring, and the quinolone group would be destroyed before the heteroatom during the degradation of NX. This work provides new insights for the treatment of antibiotic pollution.

The FLiNaK-CeF3 molten mixture: A comprehensive structure examination by means of ab initio molecular dynamics

• The FLiNaK-CeF3 melt was simulated within ab initio molecular dynamics. • Cerium is surrounded by 7 (57% of cases), 8 (28%) or 6 (11%) fluorines. • The mean lifetime of Ce-F pairs is 4.3 picoseconds. • The melt does not contain long-lived complex ions. The local structure of the 0.85 FLiNaK – 0.15 CeF 3 melt has been revealed by means of ab initio molecular dynamics. According to the simulation results, cerium in the melt is mainly surrounded by 7 (57% of cases), 8 (28% of cases), or 6 (11% of cases) fluorine ions. In the predominant case of coordination, one of the seven fluorine ions is located at a slightly larger distance from cerium. The average lifetime of Ce-F pairs is 4.3 picoseconds or about 20 periods of vibration. The moderate lifetime of this pair, along with the calculated vibrational densities of states and self-diffusion coefficients, allows us to conclude that the melt is absent of long-lived complex ions.

NiCoAl Ternary Metal Hydroxides Prepared by Fluorine Ion Assisted Electrodeposition Process for Long Lifespan Supercapacitor Electrodes

NiCo-based layered double hydroxides (NiCo-LDHs) have plenty of superior properties as electrode materials of supercapacitors, while the poor cycle performance heavily limits their application. An effective strategy to tackle this issue is to dope inactive Al that could stabilize the metallic layers to form ternary hydroxides. However, the desired ternary electrodes with appropriate content of Al3+ can hardly be prepared by conventional electrodeposition due to the great difference in solubility product constants (K sp) of corresponding hydroxides, where the non-electroactive Al(OH)3 (K sp = 1.3 × 10‒33) are preferentially deposited than the hydroxides of nickel and cobalt (K sp = 2.0 × 10‒15, 1.6 × 10‒15). Here, we propose a novel electrodeposition method assisted by F‒ to control Al3+ content in NiCoAl-LDHs. By adjusting the concentration of F‒ in the electrolyte, Al3+ content, as well as the morphology and electrochemical performance of the electrodes, could be manipulated. With the optimum ratio of F− to Al3+, the as-obtained electrode shows high specific capacitance along with a long lifespan (54.1%, 10000 cycles). An asymmetric supercapacitor is assembled using active carbon as the negative electrodes, which displays the maximal energy density of 35.5 Wh kg−1 at the power density of 477.3 W kg−1, with a long lifespan (75%, 10000 cycles).

Simultaneous fluorination and purification of natural block coaly graphite into fluorinated graphene with tunable fluorination degree

Fluorinated graphene (FG) holds great promise for various applications, but the cost-effective production of FG is still challenging because of the high cost of the starting material such as fluorinated graphite, graphene and graphene oxide. Herein, a novel approach to prepare FG through electrochemical exfoliation of the starting natural block coaly graphite (NBCG) mineral, followed by a hydrothermal reaction is reported. This method uses NH4F solution in the whole process as fluorinating agent to provide fluoride source and purification agent to remove impurity minerals in natural graphite. The morphology, chemical composition and microstructure of the starting NBCG, a series of fluorinated graphene oxide (FGO) samples after electrochemical exfoliation and FG samples after hydrothermal process were characterized in detail by a number of analytical techniques such as TEM, SEM, XPS, TGA, XRD and Raman. The thick and compact graphitic platelets of NBCG have a considerable decrease in the thickness and lateral size during the process, and the prepared FG consists of thin separated nanosheet with a low ash content. Moreover, this method is effective in tuning the fluorination degree of FG with tunable electrical conductivity through the control of the electrolyte concentration in the first step of electrochemical exfoliation. The formation mechanism of FG from NBCG is proposed. It reveals that the electrochemical process results in the oxidation of NBCG and the adsorption of fluorine ions, and those oxygen-containing groups are essential for the further fluorination in subsequent hydrothermal process. Overall, this method paves a way to prepare FG with a low cost due to the avoid of prerequisite of crushing, grinding and purifying procedures for NBCG.

A new era in fundamentals of bone homeostasis: biocompatibility of bone mineral doped fluoride ions with osteoblast cells in the balance of calcium and phosphate metabolism

Aim: The use of biocompatible bone tissue grafts, filling materials, bone minerals, and implants, particularly in medicine and dentistry studies, has expanded significantly in recent years, as have expectations from the materials. We aimed to test the biocompatibility and wound and tissue biocompatibility of many grafts and similar materials used in medicine and dentistry with tests such as cytotoxicity, scratch assay, cell adhesion, and hemolysis.&#x0D; Material and Method: In this study, the interaction of fluorine ions with a dental material was investigated by biological activity experiments. In addition, studies were carried out on important osteoblast cells for tissue regeneration control. For this process, cell migration analysis, which we do not encounter frequently in the literature, was used to examine the interaction of cells with biomaterials more sharply.&#x0D; Results: Flor ions do not create a cytotoxic effect and also increase the viability of osteoblasts which is important for tissue regeneration and are bone precursor cells.&#x0D; Conclusions: In this study, in which the efficiency of osteoblast cells was discussed, it was concluded that 2% fluorine added material had more effective biological results compared to the increase in fluorine ion ratio.

Study on the galvanic corrosion of titanium and stainless steel couple with the synergistic effect of proton and fluoride ion

The galvanic corrosion of titanium/304 stainless steel (TA1/304SS) couple was investigated in neutral and acidic solution with and without fluorine ion (F-) using macro-electrochemical technique and scanning electrochemical microscope (SECM). The results show that the synergistic effect of H+ and F- affects the passive film on the surface of galvanic couple, resulting in a great change in heterogeneous reaction rate constant and surface electrochemical activity characterized by approach curve and surface mapping of SECM in feedback mode. In addition, a typical polarity reversal occurs in pH = 2.0 acidic solution with adding F- which the TA1 is anodic to 304SS.

F−@d4r, a New Type of Acidic Catalytic Site in Zeolite

As a solid acid, zeolite has been widely used in many fields such as tail gas treatment, petrochemical engineering, and the fine chemical industry. F− has been widely used in the synthesis of pure silica or high silica zeolites. To balance the charge of organic structure directing agents (OSDA), F− is often found located at the center of the double-4-rings (d4r) of the as-made zeolites. During calcination, fluorine ion is removed with the OSDA. We screened a series of composition building units and found that d4r is capable to retain F− in zeolite structure. We introduce the F− back after the calcination to create an unprecedented type of acid site, i.e., F−@d4r in pure silica zeolites ITQ-12. The F−@d4r species is thermal stable up to 300 °C. ITQ-12 with F−@d4r shows substantial catalytic activity in Biginelli reaction. Furthermore, the catalytic performance is proved to be positive correlated with the presence of F−@d4r, indicating the mild acid catalytic property of F−@d4r.

Fluorine-plasma treated AlGaN/GaN high electronic mobility transistors under off-state overdrive stress

Influences of off-state overdrive stress on the fluorine-plasma treated AlGaN/GaN high-electronic mobility transistors (HEMTs) are experimentally investigated. It is observed that the reverse leakage current between the gate and source decreases after the off-state stress, whereas the current between the gate and drain increases. By analyzing those changes of the reverse currents based on the Frenkel–Poole model, we realize that the ionization of fluorine ions occurs during the off-state stress. Furthermore, threshold voltage degradation is also observed after the off-state stress, but the degradations of AlGaN/GaN HEMTs treated with different F-plasma RF powers are different. By comparing the differences between those devices, we find that the F-ions incorporated in the GaN buffer layer play an important role in averting degradation. Lastly, suggestions to obtain a more stable fluorine-plasma treated AlGaN/GaN HEMT are put forwarded.

Removal of Fluoride from Phosphogypsum Leaching Solution with Phosphate Tailing Based Layered Double Hydroxides: Kinetics and Equilibrium Isotherms

In this work, ternary and quaternary layered double oxides (PTB-LDO3 and PTB-LDO4) based on phosphate tailings were synthesized by the coprecipitation method. The as-prepared samples were characterized and applied to remove fluorine ions from a phosphogypsum leaching solution. The results indicated that both the precursor of PTB-LDO3 and PTB-LDO4 showed a layered structure with characteristic diffraction peaks of hydrotalcite. Compared with PTB-LDO4, PTB-LDO3 exhibited better adsorption performance at pH 5–6 and a dosage of 0.04 mg L−1. The adsorption kinetics results revealed that the adsorption of fluorine by PTB-LDO3 and PTB-LDO4 reached the adsorption equilibrium in about 3 h, and followed the pseudo-second-order model. The adsorption data could be fitted better with the Langmuir isotherm with the maximum adsorption amounts of 26.03 mg g−1 and 15.66 mg g−1 for PTB-LDO3 and PTB-LDO4, respectively. The adsorption of fluorine by PTB-LDO3 and PTB-LDO4 were both spontaneous and exothermic, and exhibited excellent reusability and stability. This study provides a possibility for the combined treatment of phosphorus chemical solid waste (phosphorus tailings) and phosphorus chemical wastewater (phosphogypsum leaching liquid).

Bimetallic sulfide nanoneedle arrays for lithium ion storage: monocrystalline versus polycrystalline

Growing mixed metal sulfides onto conductive substrates is promising in constructing self-supported flexible electrodes. However, most mixed metal sulfides grown on conductive substrates exhibit polycrystalline properties, while single crystallites are rarely reported due to the Kirkendall effect during the anion exchange process. In this work, single-crystalline CoNi2S4 directly grown on carbon cloth is obtained via tuning the diffusion of involved species with the help of fluorine ions during the anion exchange process. The received single-crystalline CoNi2S4 exhibits better electrochemical properties than the polycrystalline counterpart, establishing its significance as an electroactive material for lithium-ion batteries. Ex-situ data indicate that the single-crystalline CoNi2S4 particles exhibit local homogeneity and higher active material utilization upon lithiation/delithiation process, accounting for the enhanced electrochemical performance. These results highlight the importance of single-crystal active materials in constructing self-supported electrodes and reveal a promising opportunity for obtaining high-performance flexible electrodes.