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1.
Molybdenum trioxide (MoO3) has attracted considerable attention due to their typical two-dimensional layered structure consisting of double layers of edge- and vertex-sharing MoO6 octahedral being weakly held together by van der Waals bonds. These MoO3 nanostructures and their polymer composites are currently drawing interest for the potential applications of Li batteries, supercapacitors, and other electrochemical as well as electrochromic display devices. In this paper, we report the synthesis of MoO3 nanobelts and polyethylene glycol (PEG) surfactant MoO3 nanobelts by hydrothermal method. Structure and morphology of the samples were investigated by X-ray diffraction, Fourier transform spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The pure MoO3 nanobelts show an initial specific capacity of 275 mAh g−1, whereas the 0.5 mol% PEG surfactant MoO3 nanobelts show 307 mAh g−1 at constant current density of 30.7 mA g−1 with the 1.0–3.0 V vs. Li/Li+ potential range. It was found that PEG surfactant MoO3 nanobelts show not only a high initial specific capacity but also show better cyclic performance compared with that of pure MoO3 nanobelts. The PEG surfactant MoO3 nanobelts show stability and improvement of the specific capacity due to decreasing the length, width, and thickness of the nanobelts by surface reaction. Electrochemical impedance spectroscopy reveals that the PEG surfactant MoO3 nanobelts exhibit low electrode resistance compared with pure MoO3 nanobelts.  相似文献   

2.
Bare TiO2 and Cu-doped TiO2 nanoparticles with different nominal doping amounts of Cu ranging from of 0.5 to 5.0 mol% were synthesized using the modified sol–gel method. The samples were physically characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller-specific surface area, UV–Vis diffuse reflectance spectroscopy, zeta potential, X-ray photoelectron spectroscopy, inductively coupled plasma, and photoluminescence techniques. The Cu-doped TiO2 exhibited good photocatalytic activity in mineralization of oxalic acid and formic acid under visible light irradiation. Photomineralization of oxalic and formic acids under visible light irradiation revealed greatly enhanced photoactivity exhibited by the 2.0 mol% Cu-doped TiO2 photocatalyst compared to bare TiO2 . The enhanced photocatalytic performance arises from copper ion doping in the TiO2 structure, leading to an extended photoresponsive range, enhanced photogenerated charge separation, and transportation efficiency.  相似文献   

3.
Ag/Bi2WO6 nanocomposites were successfully synthesized by a combination of hydrothermal method and ultrasonic vibration. The phases, vibration modes, constituents and morphologies were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The visible-light-driven photocatalytic activitiy of 0–10 wt% Ag/Bi2WO6 samples was studied by determining the photodegradation of rhodamine B under xenon lamp. In this research, 10 wt% Ag/Bi2WO6 nanocomposites exhibit the highest efficiency and have the promising photocatalytic properties for waste water treatment.  相似文献   

4.
In3+-doped BiVO4 nanoparticles with enhanced visible light activity have been successfully synthesized by a hydrothermal method. The synthesized materials were characterized by X-ray diffraction, Raman, X-ray photoelectron spectroscopy, scanning electron microscopy, BET surface areas analysis, and ultraviolet–visible diffuse reflectance spectra. In comparison with pure BiVO4, the In3+-doped BiVO4 displayed greater photocatalytic activity in the degradation of methyl blue under visible light illumination. All samples possessed a single monoclinic structure. The introduction of In ions resulted in structural distortion and the decreased band gap energy, producing more electrons and holes for photocatalytic reaction. In the meantime, the doping In ions entails a red shift in the absorption edge and an increase in the intensity of light absorption. The best photocatalytic performance was obtained with the BiVO4 sample containing 5.0 mol% In ions.  相似文献   

5.
Molybdenum trioxide (MoO3) represented an excellent photocatalytic performance with many applications, including degradation of organic contaminants and splitting of water. This paper presented a new route to synthesize MoO3 nanobelts with high aspect ratios and crystallinity by a hydrothermal technique. This work showed that the as-synthesized nanobelts exhibited strong photocatalytic activity to degrade an organic dye of Rhodamine B (RhB) in aqueous solution under the exposure of the light source in the near infrared wavelength range, significantly improving the photocatalytic activity of the nanobelts. The results also showed that for a small concentration of RhB at 7.5 mg/L a complete photodegradation (for a given MoO3 nanobelts quantity of 0.1 g) can be reached after exposing for 60 min. For all concentrations of the RhB solution, the photodegradation exhibited an exponential dependence on the exposure time followed by a sudden shutdown, but no complete photodegradation can be reached. Also, the residual quantity of RhB in solution after the photocatalytic reaction was determined by the initial RhB concentration. The photocatalytic degradation can be interpreted by the pseudo–first-order equation for the absorption of liquid/solid based on solid capacity; thus, photocatalytic degradation can be attributed to the interaction between the photoexcited electrons in the substrate and the antibonding orbital of the RhB in solution. The sudden shutdown was due to the inability of the photoexcited electrons in the substrate hopping to the antibonding orbital of RhB in the presence of the RhB intermediate products from the degraded RhB. In addition, this work showed that the photocatalytic reaction can be recovered after a thermal treatment of postreacted MoO3 nanobelts, enhancing the utilization efficiency of the catalysis.  相似文献   

6.
The physical and electrochemical properties of sol-gel synthesized nickel-doped tin oxide (NTO) thin films were investigated. The X-ray diffraction results showed that NTO samples exhibited a tetragonal structure. The average crystallite size and the unit cell volume of the films were reduced by Ni increment, while the stacking fault probability was increased. Furthermore, the field-emission scanning electron microscopy images clearly displayed that the worm-like surface morphology of the SnO2 thin films was altered to the spherical feature in 3 and 10 mol% NTO samples. Moreover, by virtue of Ni incorporation, the average transparency of the SnO2 thin films rose up from 67 to 85% in the visible region; also, the optical band gap of the SnO2 sample (3.97 eV) increased and the thin film with 3 mol% dopant concentration showed a maximum value of 4.22 eV. The blue/green emission intensities of photoluminescence spectra of SnO2 thin film changed via Ni doping. The Hall effect measurements revealed that by Ni addition, the electrical conductivity of tin oxide thin films altered from n- to p-type and the carrier concentration of the films decreased due to the role of Ni2+ ions which act as electron acceptors in NTO films. In contrast, 20 mol% Ni-doped sample had the highest mobility about 9.65 cm2 (V s)?1. In addition, the cyclic voltammogram of NTO thin films in KOH electrolyte indicated the charge storage capacity and the surface total charge density of SnO2 thin films enhanced via Ni doping. Moreover, the diffusion constant of the samples increased from 2?×?10?15 to 6.5?×?10?15 cm2 s?1 for undoped and 5 mol% dopant concentration. The electrochemical impedance spectroscopy of the NTO thin films in two different potentials showed the different electrochemical behaviors of n- and p-type thin films. It revealed that the 20 mol% NTO thin film had maximum charge transfer at lower applied potential.  相似文献   

7.
Spindle-like TiO2 nanostructures was prepared by a simple one pot solvothermal method followed by calcination at 400 °C for 3 h. The sample was characterized using various techniques such as X-ray diffractometer, transmission electron microscopy, Fourier transform infrared spectroscopy and UV–Vis absorption spectroscopy. The crystal structure of TiO2 nanostructure was measured by X-ray diffractometer. According to the XRD result, the peaks in the sample can be indexed to anatase phase of TiO2. The morphological characterization of TiO2 sample was examined by transmission electron microscopy. The synthesized sample consisted of spindle-like shape with size in the range of 50–70 nm. The band gap value of Spindle-like TiO2 nanostructures is 2.92 eV, which is lower than that of bulk TiO2 of 3.2 eV. The FTIR bands observed at 493, 443 and 428 cm?1 confirms the presence of TiO2. The Spindle-like TiO2 nanostructures showed photodegradation ability for methyl orange and methyl blue dye. The reuse evaluation of the Spindle-like TiO2 nanostructures showed that their photocatalytic activity had good durability.  相似文献   

8.
CdS-ZIF-8 photocatalyst was prepared by introducing a ZnO-rich zeolitic imidazolate framework-8 (ZIF-8) during synthesis of CdS by a facile solvothermal method, using ZnO-rich ZIF-8 and cadmium acetate [Cd(Ac)2] as support and CdS precursor, respectively. The introduction of ZnO-rich ZIF-8 and the photodegradation performance of the catalyst for methylene blue (MB) organic dye were systemically investigated. The CdS-ZIF-8 catalysts were also characterized using X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy, N2 adsorption–desorption measurements, Fourier-transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy. The results indicated that CdS-ZIF-8 contained ZIF-8, CdS, and ZnO phases. The CdS in CdS-ZIF-8 catalysts exhibited smaller particle size compared with pure CdS. Furthermore, compared with pure CdS, CdS-ZIF-8-30 with introduction of ZnO-rich ZIF-8 exhibited higher surface area (77.3 m2/g) and pore volume (0.103 cm3/g). EDX and FT-IR results suggested that a CdS/ZnO heterostructure was formed, which effectively reduced recombination of photogenerated electron–hole pairs. Radical trapping experimental data and band edge position analysis revealed that Z-scheme behavior also played a role in the system. Relying on the combined effect of their structure, the photodegradation efficiency of all the CdS-ZIF-8 catalysts was obviously superior to that of pure CdS for degradation of MB under visible-light irradiation. Photodegradation results illustrated that CdS-ZIF-8 with introduction of 30 mg ZnO-rich ZIF-8 (denoted as CdS-ZIF-8-30) exhibited optimal photodegradation activity.  相似文献   

9.
Large-scale Li1+x V3O8 nanobelts were successfully fabricated using filter paper as deposition substrate through a simple surface sol–gel method. The nanobelts were as long as tens of micrometers with widths of 0.4–1.0 μm and thickness of 50–100 nm. The nanobelts were characterized by X-ray diffration (XRD), Fourier infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM). The formation mechanism of the nanobelts was investigated, showing that the morphology of the nanobelts is mainly determined by the calcination temperature. Electrochemical properties of the Li1+x V3O8 nanobelts were characterized by charge–discharge experiments, and the results demonstrate that the Li1+x V3O8 nanobelts exhibit a high discharge capacity (278 mAh g−1) and excellent cycling stability.  相似文献   

10.
The orthorhombic molybdenum trioxide (α-MoO3) nanobelts and polyvinyl pyrrolidone (PVP) surfactant MoO3 nanobelts with high quality were prepared through hydrothermal synthesis. The morphology and microstructure of the samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The nanobelts with rectangular cross-section have an orthorhombic phase structure, preferentially grow in [001] direction. The results showed that the H atoms in polyvinyl pyrrolidone are H-bonded with the O atoms in the MoO bonds of MoO3 nanobelts. When MoO3 is modified by the intercalation of PVP, it is effectively shielded against electrostatic interaction between the MoO3 interlayer and Li+ ions. The specific capacity of pure MoO3 nanobelts battery and (PVP)0.2MoO3 nanobelts exhibit as 195 mAh g−1 and 237 mAh g−1, respectively after 14 cycles, suggests that the stability of surfactant material is worthy.  相似文献   

11.
The paper investigates the structural, optical and photocatalytic activity of large surface area single crystalline copper (Cu) doped SnO2 nanorods (NRs) synthesized by a novel one-step microwave irradiation method. Powder X-ray diffraction (XRD) analysis confirms that both pure and Cu doped SnO2 are tetragonal rutile type structure (space group P42/mnm) formed during the microwave process within 10 min without any post annealing treatment. Transmission electron microscopy (TEM) reveals that the as synthesized Cu doped SnO2 samples exhibited rod-like shape and the length was less than 80 nm and diameter was about few nanometers. Typical selected-area electron diffraction (SAED) pattern indicates that, the growth direction of Cu–SnO2 nanorod is along [110] direction. The variety of phonon interaction in the pure and Cu doped SnO2 is observed by Raman spectroscopy. Electron paramagnetic resonance and X-ray photoelectron spectroscopy (XPS) confirms that the presence of copper and tin as Cu2+ and Sn4+ in state, respectively. The photocatalytic activity was monitored via the degradation of methylene blue (MB) and Rhodamine B (RhB) dyes and the Cu–SnO2 showed better photocatalytic activity than that of pure SnO2. This could be attributed to the effective electron–hole separation by surface modification.  相似文献   

12.
SiO2/TiO2 hybrid nanofibers were prepared by electrospinning and applied for photocatalytic degradation of methylene blue (MB). The phase structure, specific surface area, and surface morphologies of the SiO2/TiO2 hybrid nanofibers were characterized through thermogravimetry (TG), X-ray diffraction (XRD) analysis, Brunauer–Emmett–Teller (BET) analysis, scanning electron microscopy (SEM), etc. XRD measurements indicated that doping of silica into TiO2 nanofibers can delay the phase transition from anatase to rutile and decrease the grain size. SEM and BET characterization proved that silica doping can remarkably enhance the porosity of the SiO2/TiO2 hybrid nanofibers. The MB adsorption capacity and photocatalytic activity of the SiO2/TiO2 hybrid nanofibers were distinguished experimentally. It was found that, although increased silica doping content could enhance the MB adsorption capacity, the intrinsic photocatalytic activity gradually dropped. The SiO2 (10 %)/TiO2 composite nanofibers exhibited the highest MB degradation rate, being superior to SiO2 (20 %)/TiO2 or pure TiO2.  相似文献   

13.
The main objective of this work is to control the structural, textural and electrical properties of the system prepared by mixing molybdenum oxide with different amounts of germanium. The system is expected to be suitable as a catalyst for the photodegradation of methyl red (one of the dyes group) and the results of this study can throw some light on the relationship between the properties of this system and the extent of the dye degradation as indicated by the measurements of the photocatalytic activity. The composite materials (GexMoO3) were prepared by solid-state reaction between germanium and molybdenum oxide. The mixtures were made in Ge/MoO3 molar ratios of 0.01, 0.05, 0.1, 0.2, 0.5, and 1.0. The reaction was conducted in air at 700°C. The prepared samples were characterized by X-ray powder diffraction, micro-Raman spectroscopy, nitrogen adsorption measurements, diffuse reflectance spectrometry and UV-Vis absorption spectrophotometry. The addition of germanium has affected the photocatalytic activity of MoO3 as evidenced by an increase in the degradation extent of methyl red from about 14% (for pure oxide) to about 97% for GexMoO3 (x = 1). An enhancement in the photocatalytic activity was attributed to the change in the band gap and modification of the textural properties associated with the formation of GexMoO3 composites.  相似文献   

14.
Calcium stannate (CaSnO3) was successfully synthesized in the solutions containing different surfactants by cyclic microwave and calcination combination. Phase, morphology and vibration mode were characterized by X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. Growth mechanism of the products was also explained according to the analytical results. Their photocatalytic activities were tested through methylene blue (MB) degradation induced by UV radiation. In the MB solution with pH 6, the S-CTAB product showed the highest decolorization efficiency of 89.1% and the highest rate constant of 4.374?×?10?3 min?1.  相似文献   

15.
In this study, we have introduced iodine into Bi4Ti3O12 (BTO) crystals with the aim of improving their photocatalytic activities in decomposing organic pollutants. The as-prepared Idoped-BTO photocatalysts were systematically analyzed by various techniques (e.g. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy), as well as density functional theory calculation. It is confirmed that I element is successfully doped, as an I? oxidation state, in the BTO crystals by substituting the O in the perovskite-like (Bi2Ti3O10)2? blocks. The photocatalytic activities between the Ix-BTO (x = 0, 0.2, 0.4, 0.6, and 0.8) samples were compared by the photodegradation of methylene blue (MB) under simulated-sunlight irradiation, revealing that I0.4-BTO is the optimal photocatalyst having a photocatalytic activity about 3.0 times higher than that of parent BTO. Based on the experimental data and density functional theory calculation, the enhanced photocatalytic mechanism for the Idoped-BTO photocatalysts was proposed and discussed. To promote the potential application of the optimal I0.4-BTO photocatalyst, its photocatalytic performances were further investigated by the photodegradation of ciprofloxacin, tetrabromobisphenol A, tetracycline hydrochloride and methyl orange/rhodamine B (RhB)/MB mixture dyes; moreover, the effect of inorganic anions and pH values on the MB photodegradation was also investigated.  相似文献   

16.
This work reports the reforming of bio-ethanol on chitosan–TiO2 hybrid photocatalysts at ambient temperature. The influence of chitosan composition on the photocatalytic performance of chitosan–TiO2 hybrid was studied. The hybrids were characterized by CHN elemental analysis, nitrogen adsorption–desorption isotherms, thermogravimetric analysis, diffuse reflectance spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the preparation variables used for the incorporation of chitosan on TiO2 promoted changes in the morphology, superficial area, crystal size and porosity of the photocatalyst, affecting the band gap of this semiconductor and consequently the reactivity of the chitosan–TiO2 hybrids. The catalysts were evaluated for hydrogen production from ethanol under visible light. It was demonstrated that the calcination temperature of 623 K and a chitosan content of 20% were the most appropriate preparation conditions and the resulting product displays a pore size of 1.9 nm, crystal size of 11.3 nm, BET area of 178 m2 g?1 and band gap of 2.92 eV. The calcination temperature of 623 K and incorporation of 20% of chitosan obtained the same results in the conversion rate of hydrogen in comparison to the pure TiO2 P25.  相似文献   

17.
Highly efficient visible-light-driven Ag3PO4/Bi2MoO6 hybrid photocatalysts with different mole ratios of Ag3PO4 were prepared via sonochemical method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that product are cubic Ag3PO4 nanoparticles supported on orthorhombic Bi2MoO6 nanoplates. Under visible light irradiation (>420 nm), the Ag3PO4/Bi2MoO6 photocatalysts displayed the higher photocatalytic activity than pure Bi2MoO6 for the decolorization of rhodamine B (RhB). Among the hybrid photocatalysts, 10% Ag3PO4/Bi2MoO6 exhibited the highest photocatalytic activity for the decolorization of RhB due to the efficient separation of electron–hole pairs.  相似文献   

18.
以六水合硝酸锌和六水合硝酸铈?髥为原料,通过共沉淀法制备了一系列稀土Ce掺杂的纳米ZnO,并采用X射线粉末衍射(XRD)、傅里叶红外光谱(IR)、扫描电镜(SEM)、X射线能谱分析(EDS)、紫外可见漫反射光谱对其进行了全面表征。部分样品还通过X射线光电子能谱(XPS)和光致荧光光谱(PL)进行了进一步分析。分别在日光和紫外光条件下,对这一系列Ce掺杂的ZnO进行了光催化降解亚甲基蓝的性能研究,得出当Ce的掺杂量为3%(n/n)时(ZnO-3%Ce),其光催化活性最佳,光催化降解亚甲基蓝的效率均超过98%。选取ZnO-3%Ce作为催化剂,分别进一步考察其在日光和紫外光下对罗丹明B和甲基橙的光催化降解性能。研究结果表明,ZnO-3%Ce在日光和紫外光下均表现出较好的光催化降解效果,体现出良好的光降解普适性。日光下光降解效率顺序为:亚甲基蓝>罗丹明B>甲基橙,而紫外光下降解效率顺序为:罗丹明B>亚甲基蓝>甲基橙。最后,我们研究了催化剂ZnO-3%Ce的循环利用及稳定性性能。实验结果表明:该催化剂循环使用3次之后,光催化效率仍然稳定在97%以上,并且其结构和组成保持不变,体现出优异的稳定性和应用前景。  相似文献   

19.
A novel plasmonic photocatalyst, i.e., acid-etched TiO2 nanobelts attached with Ag/AgI nanoparticles (NPs) was prepared by deposition–precipitation-photoreduction method. Such surface-modified nanobelts had larger area than the normal one. Ag NPs were formed from AgI by photo-reduction under Xenon lamp irradiation. X-ray diffraction, scanning electron microscopy analysis, UV–Vis diffuse reflectance spectra and fluorescence spectra were used to characterize the structure and optical properties of the sample. The obtained sample exhibited strong photodegradation of methyl orange (MO) under visible light irradiation, which were attributed to both the surface plasmon resonance of Ag NPs and the visible light actived AgI. The photodegradation was accomplished by the transfer of photoexcited electrons from the Ag NPs to the acid-etched TiO2 nanobelts. After four cycles of photodegradation the photocatalyst was still stable. This novel photocatalyst had a high potential application in wastewater-treatment and biomedical engineering.  相似文献   

20.
以水杨酸为模板剂和还原剂,采用水热法制备得到了一种MoO3纳米带/RGO复合材料。利用XRD、SEM、TEM、拉曼光谱、恒流充放电、交流阻抗等手段对样品的结构、形貌以及电化学性能进行表征。测试结果表明,MoO3纳米带/RGO复合材料作为锂离子电池负极材料,在50mA·g-1的电流密度下可逆比容量为1000mAh·g-1,循环50次后比容量还保持在950mAh·g-1,相比于MoO3纳米带其容量保持能力和循环性能得到了显著改善。  相似文献   

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