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1.
Electroless and electroplated nickel electrodes are extensively used for hydrogen evolution reaction (HER). In the present work, TiO2-supported IrO2 mixed oxide composite was prepared and used to reinforce Ni–P electroless plates to be used as catalytic electrodes for HER. The electrodes exhibited high electrocatalytic activity when the electrodes were used for HER. All the parameters including particle size of the catalyst, surface roughness, and surface active sites were studied. The particle size of the IrO2 catalyst in the mixed oxide was found to have high influence on the catalytic activity of the electrodes. Low overpotential as low as 70 mV at a current density of 200 mA cm−2 was achieved with the mixed oxide-reinforced Ni–P electrodes.  相似文献   

2.
Bi2O2.7/Bi2Ti2O7 composite photocatalyst films are synthesized by sol–gel dip-coating. The ratio of adding Bi and Ti precursors can be controlled during the preparation process. The phase structure is confirmed by X-ray diffraction. The UV–visible diffuse reflectance spectrum shows that the composite catalysts present light absorption in the visible region. The obtained Bi2O2.7/Bi2Ti2O7 composite films possess superior photocatalytic degradation of rhodamine B, owing to the visible light response of Bi2O2.7 and the separation of photogenerated electrons and holes between the two components. As a result, the Bi2O2.7/Bi2Ti2O7 (Bi/Ti = 1:1) displays the highest photocatalytic activity under visible light or UV light irradiation for the degradation of different organic dyes, including methyl blue, methyl orange and acid orange 7.  相似文献   

3.
Novel La-doped Bi2WO6 composites were successfully prepared via a facile solvothermal method and well characterized by X-ray diffraction, Brunner?Emmet?Teller measurements, scanning electron microscopy, transmission electron microscopy/high-resolution, energy dispersive spectrometry, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, and Fourier transform infrared spectroscopy. The photocatalytic activity of modified catalysts was evaluated by degrading tetracycline hydrochloride under visible light (450?W Xe lamp irradiation). It was found 5%La-Bi2WO6 had the highest light-absorption ability, great morphology, and microstructures. The La dopant enlarged surface area and increased crystal defects, which may enhance the optical absorption activity and inhibit the recombination of the photo-generated charge carrier, respectively. After 150?min illumination, the photocatalysts that 5%La-Bi2WO6 and pure Bi2WO6 exhibited the best and worst photocatalytic performance, respectively (96.25% vs. 88.92%).  相似文献   

4.
AgBr@TiO2/GO (graphene oxide) ternary composite photocatalyst was synthesized by fabricating core–shell-structured AgBr@TiO2 and anchoring it onto the surface of GO. The obtained samples were characterized by transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, ultraviolet–visible (UV–Vis) diffuse reflectance spectrum, and photoluminescence (PL) spectroscopy. It was found that the AgBr nanoparticles were prone to aggregation while the core–shell-structured AgBr@TiO2 possessed excellent dispersity. PL analysis revealed that the ternary-structured AgBr@TiO2/GO could effectively promote the separation rate of electron–hole pairs. Photocatalytic oxidation of benzyl alcohol to benzaldehyde under visible-light irradiation was selected as probe reaction to evaluate the photocatalytic activity of the different samples. It was found that the AgBr@TiO2/GO ternary composite exhibited evidently improved photocatalytic activity compared with AgBr, AgBr@TiO2, and AgBr/GO. On the basis of the experiment results, the photocatalytic oxidation mechanism of benzyl alcohol over AgBr@TiO2/GO is tentatively discussed.  相似文献   

5.
The application of electrochemically enhanced photocatalysis in air treatment using a Nafion-based photoelectrochemical cell and TiO2/WO3 photoanodes for organic vapor photooxidation under both UV and visible light irradiation is briefly presented. In that direction, the obtained results regarding the preparation and characterization of the TiO2/WO3 photoanodes with enhanced photocatalytic activity are reviewed. Particular emphasis is given in the comparison of the photocatalytic behavior of bilayer TiO2/WO3 coatings, electrosynthesized on stainless steel mesh and powder C + mixed (WO3 + TiO2) photoanodes. The advantages of using a high surface area C + mixed (WO3 + TiO2) powder catalysts as photoanodes against their plain TiO2 + C and WO3 + C analogues are discussed.  相似文献   

6.
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   

7.
Molybdenum disulfide (MoS2) or tungsten disulfide (WS2), as a promising catalyst, is widely investigated for hydrogen evolution reaction (HER). In this work, a composite electrocatalysts MoxW1-xS2 is successfully decorated on carbon fiber paper (CFP) through a facile hydrothermal method. The three-dimensional porous CFP can enable the diffusion and penetration of electrolyte. Comparing with MoS2 and WS2 catalyst, the composite electrocatalyst MoxW1-xS2 nanosheets can expose the large number of electrochemically active sites. Hence, the as-prepared MoxW1-xS2/CFP (3:1) exhibit the outstanding HER catalytic activity with the small Tafel slope of 68 mV dec?1 and the low overpotential of ??178.4?±?0.5 mV at a current density of 10 mA cm?2. Chronoamperometric current test for 18 h confirm the long-term stability of the composite electrocatalyst.  相似文献   

8.
Most of research has been carried out for the development of electrocatalysts for hydrogen evolution reaction (HER), which are high activity and low cost. In this study, a practical, usable, highly active, cheap, and none noble metal catalyst was developed for HER. To this end, tungsten disulfide supported on silicon (WS2/Si) and on silicon nanoparticles (WS2/nano-Si) were prepared. To increase the catalytic activity of WS2/nano-Si, chemical etching was used to prepare WS2/nano-Si etched. The synthesized electrocatalysts were characterized using Fortier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction methods. To evaluate the electrochemical attributes of WS2/Si and WS2/n-Si before and after chemical etching, electrochemical impedance spectroscopy, linear sweep, and cyclic voltammetry were used. The electrochemical measurements indicated an intense activity of the WS2/nano-Si/etched, through a high density of the current and low overpotential for HER, with a small overpotential of 0.14 V, Tafel slopes as small as 45 mV dec?1, and large cathodic currents. These results show that through etching process of silicon in HF the quantities of the active sites have been changed and increased considerably.  相似文献   

9.
Noble metal-free, Cd1 − x Zn x S-based photocatalysts for hydrogen evolution from aqueous solutions of sodium sulfide and sodium sulfite upon irradiation with visible light (λ > 420 nm) have been synthesized and characterized by a complex of physicochemical methods. The effects of pH and catalyst and substrate concentrations on the rate of photocatalytic hydrogen evolution have been investigated. Under the optimal conditions, the quantum efficiency of the process is up to 12.9%.  相似文献   

10.
The conductivity and transport number of oxygen ions of Bi2O3-(10, 30, 50) vol % NiO composites are measured using the four-probe and coulomb-volumetric methods at various temperatures. It is shown that the Bi2O3-50 vol % NiO composite exhibits a high mixed ionic-electronic conductivity in the temperature range from 730 to 800°C.  相似文献   

11.
Fundamental aspects of electro deposition of PbO2-based composites containing titanium dioxide particles were studied. The content of the dispersed phase in the composite depends on the electrolyte composition and deposition conditions. Incorporation of titanium dioxide particles into PbO2 leads to significant changes in the morphology and structure of the deposit.  相似文献   

12.
Sn-doped Li-rich layered oxides of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 have been synthesized via a sol-gel method, and their microstructure and electrochemical performance have been studied. The addition of Sn4+ ions has no distinct influence on the crystal structure of the materials. After doped with an appropriate amount of Sn4+, the electrochemical performance of Li1.2Mn0.54-x Ni0.13Co0.13Sn x O2 cathode materials is significantly enhanced. The optimal electrochemical performance is obtained at x = 0.01. The Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode delivers a high initial discharge capacity of 268.9 mAh g?1 with an initial coulombic efficiency of 76.5% and a reversible capacity of 199.8 mAh g?1 at 0.1 C with capacity retention of 75.2% after 100 cycles. In addition, the Li1.2Mn0.53Ni0.13Co0.13Sn0.01O2 electrode exhibits the superior rate capability with discharge capacities of 239.8, 198.6, 164.4, 133.4, and 88.8 mAh g?1 at 0.2, 0.5, 1, 2, and 5 C, respectively, which are much higher than those of Li1.2Mn0.54Ni0.13Co0.13O2 (196.2, 153.5, 117.5, 92.7, and 43.8 mAh g?1 at 0.2, 0.5, 1, 2, and 5 C, respectively). The substitution of Sn4+ for Mn4+ enlarges the Li+ diffusion channels due to its larger ionic radius compared to Mn4+ and enhances the structural stability of Li-rich oxides, leading to the improved electrochemical performance in the Sn-doped Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials.  相似文献   

13.
14.
Selective catalytic reduction (SCR) with ammonia has been considered as the most promising technology, as its effect deals with the NOX. Novel Fe-doped V2O5/TiO2 catalysts were prepared by sol–gel and impregnation methods. The effects of iron content and reaction temperature on the catalyst SCR reaction activity were explored by a test device, the results of which revealed that catalysts could exhibit the best catalytic activity when the iron mass ratio was 0.05%. It further proved that the VTiFe (0.05%) catalyst performed the best in denitration and its NOX conversion reached 99.5% at 270 °C. The outcome of experimental procedures: Brunauer–Emmett–Teller surface area, X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction and adsorption (H2-TPR, NH3-TPD) techniques showed that the iron existed in the form of Fe3+ and Fe2+ and the superior catalytic performance was attributed to the highly dispersed active species, lots of surface acid sites and absorbed oxygen. The modified Fe-doped catalysts do not only have terrific SCR activities, but also a rather broad range of active temperature which also enhances the resistance to SO2 and H2O.  相似文献   

15.
Nanosized cobalt aluminate (CoAl2O4) was prepared by thermolysis of heteronuclear coordination compound, namely [Al2Co(C2O4)4(OH2)6]. The synthesized precursor was characterized by chemical analysis, vibrational spectra and thermal analysis. The cobalt aluminate obtained after a heating treatment of the precursor at 700 °C was characterized by IR, XRD, TEM coupled with SAED measurements. Two types of carbon-based electrodes, glassy carbon and boron-doped diamond electrodes were decorated with the obtained cobalt aluminate in order to enhance the electroanalytical performance for the tetracycline (TC) detection in the aqueous solutions. Cyclic voltammetry technique was used to determine the effect of the nanosized CoAl2O4 on the electrochemical oxidation of TC and as consequence, for TC detection at both carbon-based electrodes. The obtained cobalt aluminate exhibited the electrocatalytic activity toward TC detection in direct relation with the type of the carbon substrate, which allowed enhancing the electroanalytical parameters of TC detection in the aqueous solution.  相似文献   

16.
Two kinds of electrode materials Ni(OH)2 and Ni(OH)2@Zn(OH)2 composite are fabricated on nickel foam. Electrochemical experiments indicate Ni(OH)2@Zn(OH)2 composite deserves further study due to high specific capacitance and good cycle stability, so that it can achieve energy storage and conversion as much as possible. When the hydrothermal time is different, the electrochemical performance of the sample is also different. Accurately, samples can obtain better electrochemical performance at 15 h, and the maximum specific capacitance of Ni(OH)2@Zn(OH)2 is 7.87 F cm?2 compared to Ni(OH)2 (0.61 F cm?2) at 5 mA cm?2. Even at 50 mA cm?2, specific capacitance is 5.24 F cm?2 and rate capability is 66.6%. Furthermore, Ni(OH)2@Zn(OH)2-15 h loses 19.8% after 1000 cycles, revealing the composite has an outstanding stable cycle. These properties also indicate Ni(OH)2@Zn(OH)2-15 h is a promising electrode material.  相似文献   

17.
Li4Ti5O12/Li2TiO3 composite nanofibers with the mean diameter of ca. 60 nm have been synthesized via facile electrospinning. When the molar ratio of Li to Ti is 4.8:5, the Li4Ti5O12/Li2TiO3 composite nanofibers exhibit initial discharge capacity of 216.07 mAh g?1 at 0.1 C, rate capability of 151 mAh g?1 after being cycled at 20 C, and cycling stability of 122.93 mAh g?1 after 1000 cycles at 20 C. Compared with pure Li4Ti5O12 nanofibers and Li2TiO3 nanofibers, Li4Ti5O12/Li2TiO3 composite nanofibers show better performance when used as anode materials for lithium ion batteries. The enhanced electrochemical performances are explained by the incorporation of appropriate Li2TiO3 which could strengthen the structure stability of the hosted materials and has fast Li+-conductor characteristics, and the nanostructure of nanofibers which could offer high specific area between the active materials and electrolyte and shorten diffusion paths for ionic transport and electronic conduction. Our new findings provide an effective synthetic way to produce high-performance Li4Ti5O12 anodes for lithium rechargeable batteries.  相似文献   

18.
The sequence of phases occurring during treatment of lanthanum sulfate, La2(SO4)3 and lanthanum oxysulfate, La2O2SO4 in a hydrogen flow is established. The temperature ranges in which homogeneous La2O2S is produced are revealed: when La2(SO4)3 is a precursor, the range is 770–1220 K; in the case of La2O2SO4, the interval is 950–1220 K. The kinetic curves showing the time dependence of the yield of La2O2S is constructed and treated using the Avrami-Erofeev and contracting volume equations. The activation energies of the reactions are determined.  相似文献   

19.
Model reaction mechanisms in the biosynthesis of prostaglandin D2 (PGD2) and prostaglandin E2 (PGE2) from prostaglandin H2 with PGD2/E2 synthase were examined using the ab initio second-order Møller–Plesset perturbation method and density functional theory. The reaction was modeled similar to the isomerization of 2,3-dioxabicyclo[2.2.1]heptane to 3-hydroxycyclopentanone in the presence of MeS?. An explicit solvation of two H2O molecules was also considered, and two probable types of reaction mechanisms were demonstrated. One mechanism starts with proton abstraction from an oxygen-bound carbon at the endoperoxide by a thiolate ion and the other is stepwise and involves attack of a thiolate anion on an oxygen of the endoperoxide group in the first step with protonation of the other oxygen, followed by deprotonation from a carbon-attached oxygen to break an O–S bond to yield PGD2 or PGE2. We also found that the mPW1LYP hybrid method was superior to the B3LYP functional for systems with respect to the state-of-the-art CCSD(T) energetics.  相似文献   

20.
The three-dimensional porous Li3V2(PO4)3/nitrogen-doped reduced graphene oxide (LVP/N-RGO) composite was prepared by a facile one-pot hydrothermal method and evaluated as cathode material for lithium-ion batteries. It is clearly seen that the novel porous structure of the as-prepared LVP/N-RGO significantly facilitates electron transfer and lithium-ion diffusion, as well as markedly restrains the agglomeration of Li3V2(PO4)3 (LVP) nanoparticles. The introduction of N atom also has positive influence on the conductivity of RGO, which improves the kinetics of electrochemical reaction during the charge and discharge cycles. It can be found that the resultant LVP/N-RGO composite exhibits superior rate properties (92 mA h g?1 at 30 C) and outstanding cycle performance (122 mA h g?1 after 300 cycles at 5 C), indicating that nitrogen-doped RGO could be used to improve the electrochemical properties of LVP cathodes for high-power lithium-ion battery application.
Graphical abstract The three-dimensional porous Li3V2(PO4)3/nitrogen-doped reduced graphene oxide composite with significantly accelerating electron transfer and lithium-ion diffusion exhibits superior rate property and outstanding cycle performance.
  相似文献   

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