查看更多>>摘要：The unique structure of benzene ring and chloride ion makes chlorophenol pollutants have a great influence on biology and ecology. Due to its environmental friendliness, electrochemical methods have been widely used to degrade chlorophenol pollutants. Herein, the palladium/polyaniline/titanium (Pd/PANI/Ti) composite electrodes were prepared by the constant current method due to the high catalytic activity of palladium and the high specific surface area of polyaniline. The morphology, crystal structure, element valence, and functional groups of the composite electrodes were observed and analyzed by SEM, XRD, XPS, and FT-IR. The degradation efficiency of 2, 4-DCP in NaCl solution was up to 96.54% for 8 min and 100% for 10 min, respectively. The results show that the best removal efficiency of 2, 4-DCP by Pd/PANI/Ti electrode is as follows: the aniline concentration is 5 mL/L, the preparation voltage is 20 V, the concentration of PdCl2 is 10 μmol/L, the pH is 3, and the electrolyte NaCl concentration is 0.20 mol/L. The kinetics of the 2, 4-DCP degraded by Pd/PANI/Ti electrode was found to be pseudo-first-order kinetics and was fitted to the Langmuir–Hinshelwood model. The degradation products were analyzed by LC-EIS-MS. The removal efficiency of 2,4-DCP remained basically unchanged after 20 times of continuous use. The good removal efficiency of 2, 4-DCP indicates that this electrode is a promising material in the practical application of removing chlorophenol pollutants from water. Finally, the degradation pathway of 2,4-DCP was put forward.
查看更多>>摘要：The blue-green emitting La2MgZr1-xSnxO6: 0.02Bi3+ (x = 0–1, abbreviated as LMZ: Bi3+, xSn4+) phosphors with a double-perovskite structure were prepared through a conventional high-temperature solid-state method. A complex ionic substitution phenomenon of selective occupation of Bi3+ in the host of LMZ was observed with Sn4+ doping which was explained on the basis of Rietveld refinement, density functional theory (DFT) calculation and UV–vis spectroscopy results. Fluorescence spectrum analysis showed that LMZ: 0.02Bi3+ emitted a broad green light band with a range of 375–650 nm. With the increase of the Sn4+ concentration replacing Zr4+, the intensity of green light was firstly enhanced and then gradually decreases until disappeared. The emission peak of blue light appears near 400 nm and then its intensity gradually increased. Through Gaussian deconvolution and fluorescence decay curve, it was found that there were two luminescence centers in LMZ: 0.02Bi3+, and three luminescence centers in LMZ: 0.02Bi3+,0.6Sn4+, respectively, which were determined by the Van Uitert empirical formula combined with the energy level splitting theory. The above results demonstrate that how to tune emission color by the substitution of B-site in double perovskite phosphors, which is attractive for future applications.
查看更多>>摘要：The cost associated with hole-transporting materials (HTMs) and electrodes made of noble metals is a recurrent problem for the widespread application of perovskite solar cells (PSCs). Biomass-derived carbons are green materials that have been incorporated in the electrodes of diverse electrochemical devices to reduce cost, improve environmental sustainability, and augment the specific surface area (SSA). Here, carbonized bacterial cellulose (CBC) and carbonized macadamia nutshell (CMNS) were combined with commercial carbon paste (CP) to fabricate counter electrodes (CEs) integrated into highly-stable all-inorganic CsPbBr3 PSCs synthesized by thermal evaporation. When electrically-conductive CP was mixed with either 0.1% CBC or CMNS, the power conversion efficiency was improved to 4.76% and 6.18%, respectively, compared to 4.45% for a PSC equipped with pure CP. The better performance of CMNS versus CBC in the CEs can be explained by a larger SSA, a more suitable work function, and a lower sheet resistance. The outstanding surface area of CMNS is likely to improve hole scavenging efficiency in the PSCs by increasing the number of contacts with CsPbBr3. The long-term stability of the all-inorganic CsPbBr3 PSC at high temperature was also improved with the CP CE modified with CMNS. These results demonstrate that adding CBC or CMNS to CP for the fabrication of CEs in a suitable ratio improves the photoelectric properties of all-inorganic PSCs and thus opens possibilities for novel applications for renewable and earth-abundant biomass-derived carbons.
查看更多>>摘要：Aiming for efficient cold cathode applications in low dimension, pure and rGO wrapped gallium oxide micro/nanobricks were synthesized via cost-effective solid-state and hydrothermal routes. The synthesized samples were characterized using X-ray diffractometry, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy for phase, morphology, composition, and structure-related investigations. In addition, all samples were thoroughly investigated, and as a result, experimental modifications were adapted accordingly for improving the field emission properties. Remarkable enhancement of field-emission performances with a high emission current-density of 1.08 mA/cm2 and enhancement factor of 7400 has been observed as an effect of rGO wrapping. The results have been correlated with the increase in the availability of emission sites and proper charge carrier transport between the components in the hybrid structure. Furthermore, the probability of charge carrier transport across Ga2O3 /rGO junction was validated using theoretical analysis via DFT calculations. Moreover, the improvement of field emission properties due to rGO wrapping was also predicted from ANSYS simulations. Hence, 3.5 times increment of current density and 2.5 times lowering of turn-on field, the Ga2O3/rGO hybrid system emerged as one of the most functional future cold cathodes. This work opens up new applications for Ga2O3-based composites beyond the sensing and catalysis sectors.
查看更多>>摘要：A mercury-based sulfate nonlinear optical (NLO) material, HgSO4, was successfully grown using a hydrothermal method. It crystallizes in the polar space group Pmn21 and forms a three-dimensional spatial network structure consisting of [HgO8] polyhedras and [SO4] polyhedras. The powder second harmonic generation (SHG) measurement showed that HgSO4 is a phase-matching material and has a very strong SHG efficiency of 11 times that of KDP. Such a remarkable SHG response is due to the well-ordered arrangement of the distorted [HgO8] and [SO4] polyhedras. In parallel, large bandgap (4.13 eV) and laser damage threshold (26.5 × AgGaS2) are exhibited. Further characterizations showed that this compound possesses a large birefringence and a wide transmission window from the near-UV to mid-IR, suggesting that HgSO4 may be an excellent mid-IR NLO crystal.
查看更多>>摘要：In the present work, the ultrasonic-assisted co-precipitation method was applied to synthesize pure Mn3O4, Samarium-doped Mn3O4, and Zirconium-doped Mn3O4. Furthermore, as an additional stage, the hydrothermal method was utilized to prepare zeolite 4 A exploiting a natural zeolite (clinoptilolite). Afterward, some of the prepared Mn3O4-based photocatalysts were immobilized using the synthesized zeolite 4 A as a proficient support, resulting in the synthesis of some novel Mn3O4-based nanocomposites (including Sm(0.02)-Mn3O4/Zeolite 4 A and Zr(0.02)-Mn3O4/Zeolite 4 A). X-ray diffraction (XRD), Diffuse Reflectance Spectroscopy analysis (DRS), Scanning Electron Microscopy (SEM) as well as Energy Dispersive X-Ray Spectroscopy (EDX) were the techniques utilized for the characterization of the prepared samples. The XRD patterns of the doped Mn3O4 samples validated the presence of Hausmannite structure, excluding any impurities. Eventually, to evaluate the photocatalytic performance of synthesized photocatalysts, methylene blue (MB) aqueous solution as an organic pollutant was chosen to study. According to the results, Sm(0.02)-Mn3O4/Zeolite 4 A nanocomposite and Zr(0.1)-Mn3O4 nanoparticles revealed an outstanding photocatalytic efficiency of 95. 5% and 98.4% in photocatalytic removal of MB in the 210 min, respectively.
查看更多>>摘要：Titanium dioxide (TiO2) is a typical lithium-ion storage material with the advantages of stable structure, abundant source and easy preparation. To further improve the lithium-ion diffusion, we employ a sol-gel method with a silicon dioxide (SiO2) template to prepare flower-like TiO2 hollow microspheres (TiO2 HM) with a loose surface structure composed of nanosheets. The as-prepared TiO2 exhibits a large specific surface area (120.3 m2/g) and pore volume (0.13 cm3/g), which favors the penetration of electrolyte. Moreover, the TiO2(B)/anatase/amorphous mixed phases have multitudes active sites for rapid lithium-ion diffusion. As an anode for lithium-ion batteries (LIBs), TiO2 HM deliver a high first discharge specific capacity (721 mAh/g, 0.1 A/g), superior rate capacity (84 mAh/g, 2.0 A/g) and long life (121 mAh/g, 1000 cycles, 1.0 A/g). Electrochemical analysis proves that Li+ ions storage of TiO2 HM is mainly dependent on pseudocapacitance (87%, 2.0 A/g). Therefore, it is an effective way to regulate morphology, composition and pseudocapacitance property with the SiO2 template of TiO2 for promising LIB anodes.
查看更多>>摘要：Tin-doped spinel has been reported as a classical soft magnetic material. In this study, series spinels of Fe3-xSnxO4 were synthesized via a novel low-temperature solid-state reaction process from natural magnetite and cassiterite. The substitution mechanisms between Sn4+ and Fe3+ were investigated by means of XRD, TEM, XPS, M?ssbauer, FT-IR analysis, etc. The results indicated that the maximum doping stoichiometric content of tin was 0.5 in Fe3-xSnxO4. The substitution occurred prior to proceeding in the octahedral void between Sn4+ and Fe3+, because the ion radius of Sn4+ is very similar to Fe3+ and much smaller than Fe2+. In addition, the effects of tin content on the magnetic properties were revealed. The optimal coercivity value of 10.2 Oe was obtained for Fe2.9Sn0.1O4, which can be used as soft magnetic material. This is related to the lattice distortion caused by Sn4+.
查看更多>>摘要：A novel strategy of incorporating conducting additive to enhance the performance of NaMnPO4-based Na-ion supercapacitors is presented. It is observed that forming composite with a conducting polymer, leads to nearly two-fold increment in the specific capacitance of a Na-ion based system. The higher conductivity, fast Faradaic response alongside with greater number of ion transport channels lead to this improvement. Here, the best performance is obtained at an optimized polyaniline (PANi) percentage of 30 wt%, where a specific capacitance of 201 F g?1 at 1 A g?1 current density was observed. This is more than twice the value obtained by pure NaMnPO4. The fabricated supercapacitors also deliver 26.5 W h kg?1 specific energy and high cycling stability.
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Elsevier