Composites Li1-xVxCryFe1-yPO4/C(x=0.01, 0.02; y = 0.01, 0.02) were synthesized by solid-state reaction method. The influence of the content of doping vanadium and chromium on the structure of Li1-xVxCryFe1-yPO4/C was investigated by XRD, while the morphology of powders was observed by SEM. The investigation of the electrochemical performances showed that the Li0.99V0.01Cr0.02Fe0.98PO4/C material has a higher capacity. At 0.1 C discharging rate, it is capable of delivering reversible specific capacity of 163.8 mAh/g with fairly stable cycleability. 相似文献
Constructing a Z-scheme is a significant approach to improve the separation of photogene rated carriers for effective organic pollutant degradation.Herein,a BiVO4/ZnIn2S4(BZ) Z-scheme composite was successfully synthesized,and applied to photodegrade methyl orange(MO) irradiated by a LED lamp.Anchoring the BiVO4 on the ZnIn2S4 nanoparticles promoted the separation of photogenerated electronholes and broadened the light response range.The detailed characterizations,including surface morphology,elements valence state,and photocurrent performance,demonstrated that the enhanced separation of photogenerated carriers was the pivotal reason for the enhanced photocatalysis reaction.Benefiting from the excellent photocatalytic characteristics,the 5% mass ratio of BZ composite presented the highest MO degradation rate of 0.00997 min^-1,which was 1.9 and 10.3 times greater than the virgin ZnIn2S4 and BiVO4,respectively.Furthermore,the BZ hybrid materials indicated a well photo-stability in the four recycling tests. 相似文献
The threat and global concern of energy crises have significantly increased over the last two decades. Because solar light and water are abundant on earth, photocatalytic hydrogen evolution through water splitting has been considered as a promising route to produce green energy. Therefore, semiconductor photocatalysts play a key role in transforming sunlight and water to hydrogen energy. To date, various photocatalysts have been studied. Among them, TiO2 has been extensively investigated because of its non-toxicity, high chemical stability, controllable morphology, and high photocatalytic activity. In particular, 1D TiO2 nanofibers (NFs) have attracted increasing attention as effective photocatalysts because of their unique 1D electron transfer pathway, high adsorption capacity, and high photoinduced electron–hole pair transfer capability. However, TiO2 NFs are considered as an inefficient photocatalyst for the hydrogen evolution reaction (HER) because of their disadvantages such as a large band gap (~3.2 eV) and fast recombination of photoinduced electron–hole pairs. Therefore, the development of a high-performance TiO2 NF photocatalyst is required for efficient solar light conversion. In recent years, several strategies have been explored to improve the photocatalytic activity of TiO2 NFs, including coupling with narrow-bandgap semiconductors (such as ZnIn2S4). Recently, microwave (MW)-assisted synthesis has been considered as an important strategy for the preparation of photocatalyst semiconductors because of its low cost, environment-friendliness, simplicity, and high reaction rate. Herein, to overcome the above-mentioned limiting properties of TiO2 NFs, we report a 2D/1D ZnIn2S4/TiO2 S-scheme heterojunction synthesized through a microwave (MW)-assisted process. Herein, the 2D/1D ZnIn2S4/TiO2 S-scheme heterojunction was constructed rapidly by using in situ 2D ZnIn2S4nanosheets decorated on 1D TiO2 NFs. The loading of ZnIn2S4 nanoplates on the TiO2 NFs could be easily controlled by adjusting the molar ratios of ZnIn2S4 precursors to TiO2 NFs. The photocatalytic activity of the as-prepared samples for water splitting under simulated solar light irradiation was assessed. The experimental results showed that the photocatalytic performance of the ZnIn2S4/TiO2 composites was significantly improved, and the obtained ZnIn2S4/TiO2 composites showed increased optical absorption. Under optimal conditions, the highest HER rate of the ZT-0.5 (molar ratio of ZnIn2S4/TiO2= 0.5) sample was 8774 μmol·g-1·h-1, which is considerably higher than those of pure TiO2 NFs (3312 μmol·g-1·h-1) and ZnIn2S4nanoplates (3114 μmol·g-1·h-1) by factors of 2.7 and 2.8, respectively. Based on the experimental data and Mott-Schottky analysis, a possible mechanism for the formation of the S-scheme heterojunction between ZnIn2S4 and TiO2 was proposed to interpret the enhanced HER activity of the ZnIn2S4/TiO2heterojunctionphotocatalysts.相似文献
The application of transition metal dichalcogenides(TMDs) as anode materials in sodium-ion batteries (SIBs) has been hindered by low conductivity and poor cyclability. Herein, we report the synthesis of CoxFe1-xS2 bimetallic sulfide/sulfur-doped Ti3C2 MXene nanocomposites(CoxFe1-xS2@S-Ti3C2) by a facile co-precipitation process and thermal-sulfurization reaction. The interconnected 3D frameworks consisting of MXene nanosheets can effectively buffer the volume change and enhance the charge transfer. In particular, sulfur-doped MXene nanosheets provide rich active sites for sodium storage and restrain sulfur loss during charging/discharging processes, leading the increase of specific capacity and cycling the stability of anode materials. As a result, CoxFe1-xS2@S-Ti3C2 anodes exhibited high capacity, high rate capability and long cycle life(399 mA·h/g at 5 A/g with an 94% capacity retention after 600 cycles). 相似文献
Different from the traditional pyrometallurgical recovery process of Li and Co from spent lithium-ion batteries, a new recovery method for Li and Co was established by converting LiCoO2 into water-soluble metal sulfates by roasting a mixture of LiCoO2 and NaHSO4·H2O. The evolution law of the mixture with increased roasting temperature was investigated by thermogravimetry-differential scanning calorimetry(TG-DSC), in situ X-ray diffraction(XRD), XRD, and X-ray photoelectron spectroscopy(XPS). The results show that the phase transition of LiCoO2 mixed with NaHSO4·H2O with increased temperature proceeded as follows:LiCoO2, NaHSO4·H2O→LiCoO2, NaHSO4→Li1-xCoO2, LiNaSO4, Na2S2O7, Na2SO4→Li1-xCoO2, Co3O4, LiNaSO4, Na2SO4→Co3O4, LiNaSO4. The reaction mechanism of this roasting process may be as follows:LiCoO2+NaHSO4·H2O→1/2Li2SO4+ 1/2Na2SO4+1/3Co3O4+1/12O2+3/2H2O, Li2SO4+Na2SO4=2LiNaSO4. 相似文献
Ferrocenyl-1,2-diketones FcCOCOR, 3, [Fc = (C5H5)Fe(C5H4)] can be prepared by oxidation of acylferrocenes FcCOCH2R or, more efficiently, by oxidation of the isomeric ketones FcCH2COR, 2. The ketones 2 are in turn readily synthesized from the salt (FcCH2PPh3)+I− via the acylated salts [FcCH(COR)PPh3]+I−. The haloacylferocenes FcCOCClx H3−x (x = 1, 2, 3, of which the x = 2 example is synthetically equivalent to a diketone) are synthesized by Friedel—Crafts acylation of ferrocene using CClxH3−xCOCl/AlCl3, but the reaction proceeds via two parallel pathways, one giving the normal acyl derivatives FcCOCClxH3−x and the other giving the reduced products FcCOCClx−1H4−x. Two diketones FcCOCOFc 3b and FcCOCOC6H4Ph 3c have been structurally characterised by single-crystal X-ray diffraction. 相似文献
The applicability of positron annihilation spectroscopy for chemical structural problems is demonstrated by two examples: For the swelling dynamics of an amphiphilic polymer network, very quick structural changes were indicated by positronium lifetime parameters at very low swelling ratios and a hydration mechanism was proposed accordingly. For the series [FexZn1−x(propyltetrazole)6](BF4)2(x=1, 0.6, 0.4, 0.1, 0), changes in the dynamic structure were revealed by positronium lifetime spectroscopy. For compounds of x>0, temperature-induced spin-crossover was detected. 相似文献
The preparation and characterization by X-ray crystallography of transition metal sulfur dioxide hexafluoroarsenates of the general formula [M(SO2)x](AsF6)2 1 (1a: M=Mn, x=2; 1c: M=Co, x=4; 1e: M=Cu, x=4) and the hexafluoroantimonate [Co(SO2)2](SbF6)2 3 is reported. The structural features of the compounds mentioned are compared with those of [Fe(SO2)4](AsF6)2 (1b) and [Ni(SO2)6](AsF6)2 (1d), reported previously. The structural diversity of transition metal sulfur dioxide complexes is discussed. 相似文献
Excess molar enthalpies HE and excess molar volumes VE have been measured, as a function of mole fraction x1, at 298.15 K and atmospheric pressure for the five liquid mixtures (x11,4-C6H4F2 + x2n-ClH2l+2), l = 7, 8, 10, 12 and 16. In addition, HE and excess molar heat capacities CPE at constant pressure have been determined for the two liquid mixtures (x1C6F6 + x2n-ClH2l+2), l = 7 and 14, at the same temperature and pressure. The instruments used were flow microcalorimeters of the Picker design (the HE version was equipped with separators) and a vibrating-tube densimeter, respectively.
The excess enthalpies of the five difluorobenzene mixtures are all positive and quite large; they increase with increasing chain length l of the n-alkane from HE(x1 = 0.5)/(J mol−1) = 1050 for l = 7 to 1359 for l = 16. The corresponding excess volumes VE are all positive and also increase with increasing l: VE(x1 = 0.5)/(cm3 mol−1) = 0.650 for l = 7 and 1.080 for l = 16. Interestingly, the excess enthalphies of the corresponding mixtures with hexafluorobenzene are only about 5% larger, whereas the excess volumes of (x1C6F6 + x2n-ClH2l+2) are roughly twice as large as those of their counterparts in the series containing 1,4-C6H4F2. Specifically, at 298.15 K HE(x1 = 0.5)/(J mol−1) = 1119 for (x1C6F6 + x2n-C7H16) and 1324 for (x1C6F6 + x2n-C14H30), and for the same mixtures VE(x1 = 0.5)/(cm3 mol−1) = 1.882 and 2.093, respectively. The excess heat capacities for both systems are negative and of about the same magnitude as the excess heat capacities of mixtures of fluorobenzene with the same n-alkanes (Roux et al., 1984): CPE(x1 = 0.5)/(J K−1 mol−1) = −1.18 for (x1C6F6 + x2n-C7H16), and −2.25 for (x1C6F6 + x2n-C14H30). The curve CPE vs. (x1 for x1C6F6 + x2n-C14H30) shows a sort of “hump” for x1 0.5, which is presumed to indicate emerging W-shape composition dependence at lower temperatures. 相似文献
Titanate nanotubes were synthesized in hydrothermal treatment of anatase titania powders and concentrated NaOH solution and their structure was investigated. It was suggested that the nanotubes might be constructed from lepidocrocite HxTi2− x/4□x/4O4 (x0.7, □: vacancy) sheets. The newly proposed lepidocrocite titanate nanotube model was supported by X-ray diffraction, electron diffraction, and thermogravimetry studies. 相似文献
Synthesis of colloidal heterostructures with rational design and controllable precision represents a promising strategy for achieving novel properties and applications. Most recently, Zhuang et al. reported a "double-buffer-layer engineering" concept that was capable of regioselectively growing magnetic Fe3O4 nanodomains only at single ends of semiconductor ZnxCd1-xS(0 ≤ x ≤ 1) nanorods. The resulting composite nanostructures exhibited chiroptical activity due to the local magnetic fields introduced by regiospecific magnetic nanodomains, highlighting the promise of controlled colloidal chemistry in synthesizing chiroptical nanostructures in the absence of chiral molecules and helical geometries. The work has been published online in Nature Nanotechnology on January 20, 2020. 相似文献
A series of CexPr1−xO2−δ mixed oxides were synthesized by a sol–gel method and characterized by Raman, XRD and TPR techniques. The oxidation activity for CO, CH3OH and CH4 on these mixed oxides was investigated. When the value x was changed from 1.0 to 0.8, only a cubic phase CeO2 was observed. The samples were greatly crystallized in the range of the value x from 0.99 to 0.80, which is due to the formation of solid solutions caused by the complete insertion of Pr into the CeO2 crystal lattices. Raman bands at 465 and 1150 cm−1 in CexPr1−xO2−δ samples are attributed to the Raman active F2g mode of CeO2. The broad band at around 570 cm−1 in the region of 0.3 ≤ x ≤ 0.99 can be linked to oxygen vacancies. The new band at 195 cm−1 may be ascribed to the asymmetric vibration caused by the formation of oxygen vacancies. The TPR profile of Pr6O11 shows two reduction peaks and the reduction process is followed: . The reduction temperature of CexPr1−xO2−δ mixed oxides is lower than those of Pr6O11 or CeO2. TPR results indicate that CexPr1−xO2−δ mixed oxides have higher redox properties because of the formation of CexPr1−xO2−δ solid solutions. The presence of the oxygen vacancies favors CO and CH3OH oxidation, while the activity of CH4 oxidation is mostly related to reduction temperatures and redox properties. 相似文献