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1.
Titanium nitride (TiN) decorated N-doped titania (N-TiO2) composite (TiN/N-TiO2) is fabricated via an in situ nitridation using a hydrothermally synthesized TiO2 and melamine (MA) as raw materials. After the optimization of the reaction condition, the resultant TiN/N-TiO2 composite delivers a hydrogen evolution activity of up to 703 μmol/h under the full spectrum irradiation of Xe-lamp, which is approximately 2.6 and 32.0 times more than that of TiO2 and TiN alone, respectively. To explore the underlying photocatalytic mechanism, the crystal phase, morphology, light absorption, energy band structure, element composition, and electrochemical behavior of the composite material are characterized and analyzed. The results indicate that the superior activity is mainly caused by the in situ formation of plasmonic TiN and N-TiO2 with intimate interface contact, which not only extends the spectral response range, but also accelerates the transfer and separation of the photoexcited hot charge carrier of TiN. The present study provides a fascinating approach to in situ forming nonmetallic plasmonic material/N-doped TiO2 composite photocatalysts for high-efficiency water splitting.  相似文献   

2.
In this study, TiO2 photocatalysts with nickel sulfide cocatalyst are prepared by loading nickel sulfide on TiO2 with solvothermal synthesis approach. The materials were prepared by glycol solvothermal method using anatase, nickel nitrate, thiourea as precursor. The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), and X-ray photoelectron spectroscopy (XPS). This is the first time to report that NiS is used as a cocatalyst with TiO2 for the photocatalytic production of H2. The results revealed that the structure and the amount of the cocatalyst loaded on TiO2 play important roles in the photocatalytic activity of NiS/TiO2 composite. The maximum evolution of H2 was obtained when NiS had hexagonal structure with content in the composite of 7 at% in relation to TiO2. The rate of H2 evolution was increased up to about 30 times than that of TiO2 alone.  相似文献   

3.
CuCr2O4/TiO2 heterojunction has been successfully synthesized via a facile citric acid (CA)-assisted sol-gel method. Techniques of X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-vis diffuse reflectance spectrum (UV-vis DRS) have been employed to characterize the as-synthesized nanocomposites. Furthermore, photocatalytic activities of the as-obtained nanocomposites have been evaluated based on the H2 evolution from oxalic acid solution under simulated sunlight irradiation. Factors such as CuCr2O4 to TiO2 molar ratio in the composites, calcination temperature, photocatalyst mass concentration, and initial oxalic acid concentration affecting the photocatalytic hydrogen producing have been studied in detail. The results showed that the nanocomposite of CuCr2O4/TiO2 is more efficient than their single part of CuCr2O4 or TiO2 in producing hydrogen. The optimized composition of the nanocomposites has been found to be CuCr2O4·0.7TiO2. And the optimized calcination temperature and photocatalyst mass concentration are 500 °C and 0.8 g l−1, respectively. The influence of initial oxalic acid concentration is consistent with the Langmuir model.  相似文献   

4.
One-dimensional (1D) Pt/TiO2 hybrid nanofibers (HNFs) with different concentrations of Pt were fabricated by a facile two-step synthesis route combining an electrospinning technique and calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) results showed that the Pt nanoparticles (NPs) with the size of 5–10 nm were well dispersed in the TiO2 nanofibers (NFs). Further investigations from the UV–Vis diffuse reflectance (DR) and X-ray photoelectron spectroscopy (XPS) analysis revealed that some Pt ions were incorporated into the TiO2 lattice as Pt4+ state, which contributed to the visible light absorption of TiO2 NFs. Meanwhile, the Pt2+ ions existing on the surface of Pt NPs resulted in the formation of Pt–O–Ti bond at Pt NPs/TiO2 NFs interfaces that might serve as an effective channel for improving the charge transfer. The as-electrospun Pt/TiO2 HNFs exhibited remarkable activities for photocatalytic H2 evolution under visible light irradiation in the presence of l-ascorbic acid as the sacrificial agent. In particular, the optimal HNFs containing 1.0 at% Pt showed the H2 evolution rate of 2.91 μmol h−1 and apparent quantum efficiency of 0.04% at 420 nm by using only 5 mg of photocatalysts. The higher photocatalytic activity could be ascribed to the appropriate amount of Pt ions doping and excellent electron-sink effect of Pt NPs co-catalysts.  相似文献   

5.
Cu2O/TiO2 nanoparticles were prepared by solvothermal method, which formed the heterostructure of Cu2O/TiO2. Due to the heterostructure, the H2 evolution rate under simulated solar irradiation was increasingly promoted. Meanwhile a certain amount of Cu particles which were confirmed by Transmission Electro Microscopy (TEM) and X-Ray Photoelectron Spectroscopy (XPS), formed on the surface of Cu2O/TiO2, and the photoactivity was accordingly further enhanced. The stabilized activity was maintained after many times irradiation. It is interesting that after a few hours irradiation the amount of Cu particles on the surface kept unchanged in the presence of Cu2O and TiO2. The Cu particles that formed during hydrogen generation reaction play a key role in the further enhancement of the hydrogen production activity. In this study, it is the first time to study the details on the formation of the stable ternary structure under simulated solar irradiation and their synergistic effect on the photoactivity of the water splitting.  相似文献   

6.
Photocatalytic hydrogen production from water or organic compounds is a promising way to resolve our energy crisis and environmental problems in the near future. Over the past decades, many photocatalysts have been developed for solar water splitting. However, most of these photocatalysts require cocatalyst to facilitate H2 evolution reaction and noble metals as key cocatalysts are widely used. Consequently, the condition of noble metal cocatalyst including the size and valence state etc plays the key role in such photocatalytic system. Here, the size and valence state effect of Pt on photocatalytic H2 evolution over platinized TiO2 photocatalyst were studied for the first time. Surprisingly, it was found that Pt particle size does not affect the photoreaction rate with the size range of several nanometers in this work, while it is mainly depended on the valence state of Pt particles. Typically, TOFs of TiO2 photodeposited with 0.1–0.2 wt% Pt can exceed 3000 h−1.  相似文献   

7.
A photocatalyst composed of graphite-like carbon nitride (g-C3N4) and TiO2 was fabricated by a simple method to calcine the mixture of melamine and TiO2 precursor. The photocatalyst has enhanced photoactivity for hydrogen evolution from water. Characterization by XRD, FTIR, SEM and elemental analysis showed that the crystal structure and morphologies of composites were affected by the amount of melamine in the composite. The UV–Vis characterization displayed that the optical absorption range of g-C3N4/TiO2 hybrid was broadened with a synergistic effect. The photoactivity for H2 evolution was shown that the best result obtained from the composite with 67 wt% melamine has about 5 times improvement compared with bare TiO2 or pure g-C3N4. The enhanced photoactivity might be related with the favorable structure resulted from heat-treatment temperature, and the content of g-C3N4 participating in wide optical absorption, separation and transportation of electronic-holes, as well as morphology of composite.  相似文献   

8.
TiO2 with exposed (001) facets were composited with CdS nanorods to construct 2D/1D heterojunction. As comparison, P25 with mainly exposed (101) facets were employed to combine with CdS nanorods. The 2D/1D heterojunction of TiO2 nanosheets and CdS nanorod displayed 3.7 times higher hydrogen generation than that of P25/CdS composites. The results indicated that TiO2 with exposed (001) facets were favorable for enhancing the photocatalytic activity of CdS via optimizing the heterojunction between TiO2 and CdS. Photoluminescence and photoelectrochemical characteristics results demonstrated that the 2D-TiO2/1D-CdS heterojunction exhibits higher separation efficiency of photoinduced carriers and superior electron transfer ability. This work exemplifies that heterojunction modification is an effective strategy to improve the efficiency of the photocatalyst composites.  相似文献   

9.
An ultrathin MoS2 was grown on CdS nanorod by a solid state method using sulfur powder as sulfur source for photocatalytic H2 production. The characterization result reveals that the ultrathin MoS2 nanosheets loaded on CdS has a good contact state. The photoelectrochemical result shows that MoS2 not only are beneficial for charge separation, but also works as active sites, thus enhancing photocatalytic activity. Compared with pure CdS, the photocatalytic activity of MoS2 loaded CdS was significantly improved. The hydrogen evolution rate on m(MoS2): m(CdS) = 1: 50 (m is mass) reaches 542 μmol/h, which is 6 times of that on pure CdS (92 μmol/h). This work provides a new design for photocatalysts with high photocatalytic activities and provides a deeper understanding of the effect of MoS2 on enhancing photocatalytic activity.  相似文献   

10.
TiO2/reduced graphene oxide composite (T-rGO) was synthesized and its performance was evaluated with photocatalytic hydrogen evolution. It was found that the hydrogen evolution rate of T-rGO increased significantly after injecting small amount of air into the vacuum pumped and UV irradiated sealed reaction cell. The IR, XPS, Raman and ESR spectra analysis indicated that the O2•−, which generated from the reaction of photoinduced electrons and the injected O2 can moderately and controllably increase the oxygen groups on graphene planar of T-rGO at ambient condition. The amount of oxygen groups on graphene planar of T-rGO will affect the p-doping concentration of graphene, thus affect the p–n junction and the performance of T-rGO for photocatalytic hydrogen evolution.  相似文献   

11.
In this study, the electronic and photocatalytic properties of core-shell heterojunctions photocatalysts with reversible configuration of TiO2 and Bi2O3 layers were studied. The core-shell nanostructure, obtained by efficient control of the sol-gel polymerization and impregnation method of variable precursors of semiconductors, makes it possible to study selectively the role of the interfacial charge transfer in each configuration. The morphological, optical, and chemical composition of the core-shell nanostructures were characterized by high-resolution transmission electron microscopy, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The results show the formation of homogenous TiO2 anatase and Bi2O3 layers with a thickness of around 10 and 8 nm, respectively. The interfacial charge carrier dynamic was tracked using time resolved microwave conductivity and transition photocurrent density. The charge transfer, their density, and lifetime were found to rely on the layout layers in the core-shell nanostructure. In optimal core-shell design, Bi2O3 collects holes from TiO2, leaving electrons free to react and increase by 5 times the photocatalytic efficiency toward H2 generation. This study provides new insight into the importance of the design and elaboration of optimal heterojunction based on the photocatalyst system to improve the photocatalytic activity.  相似文献   

12.
Anatase TiO2 films were obtained on glass substrates using a sol–gel method using titanium isopropoxide as a precursor. The thickness of the film was about 140 nm for one coating, and the thickness is controlled by the number of coating cycles. The spectra of UV-VIS absorption indicated that the absorption edge of the TiO2 films is ca. 385 nm, corresponding to the band gap energy of 3.20 eV. We obtained TiO2 films having a high activity for the hydrogen evolution from photocatalytic water cleavage. By loading with 0.3 wt% Pt rate of hydrogen production increases. No influence of film thickness and calcination temperature on the photocatalytic property is observed.  相似文献   

13.
An efficient visible-light active photocatalyst of multilayer-Eosin Y-sensitized TiO2 is prepared through linkage of Fe3+ between not only TiO2 and Eosin Y but also different Eosin Y molecules to form three-dimensional polymeric dye structure. The multilayer-dye-sensitized photocatalyst is found to have high light harvesting efficiency and photocatalytic activity for hydrogen evolution under visible light irradiation (λ > 420 nm). On the optimum conditions (1:1 initial molar ratio of Eosin Y to Fe(NO3)3, initial 10 × 10−3 M Eosin Y, and 1.0 wt% Pt deposited by in situ photoreduction), its maximal apparent quantum yield for hydrogen evolution is 19.1% from aqueous triethanolamine solution (TEOA aq). The present study highlights linking between dye molecules via metal ions as a general way to develop efficient visible-light photocatalyst.  相似文献   

14.
Well-defined SnNb2O6 nanoplates are synthesized here by a facile template-free solvothermal route in a mixed solvent of water and ethanol without an organic surfactant. The synthesized nanoplates have widths ranging from 200 to 400 nm and thicknesses in a range of 20–30 nm. The nanoplates were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–Vis spectroscopy, Raman spectrometry, and by the Brunauer–Emmett–Teller method. The variation of the lattice parameters and the optical properties of the nanoplates were discussed in detail based on the crystal and electronic structure. The SnNb2O6 nanoplates exhibited greatly enhanced photocatalytic activity in terms of the reduction of water for H2 generation under visible light irradiation as compared to the same compound prepared by a solid–state reaction method. This was mainly attributed to its higher surface area and extremely high two-dimensional anisotropy, which provided a short migration distance along the thickness direction.  相似文献   

15.
The photocatalytic evolution of hydrogen from water was investigated under various conditions over 0.6 wt% Pt-loaded nanocrystalline mesoporous TiO2 photocatalyst prepared by a single-step sol–gel process with a surfactant template. The highly crystalline photocatalyst possessed a mesoporous characteristic with high surface area and narrow monomodal pore size distribution. More specifically, the influence of the following operational parameters, namely sacrificial reagent type, initial solution pH, photocatalyst concentration, initial sacrificial reagent concentration (of the best sacrificial reagent studied), and irradiation time, was the main focus. The hydrogen evolution was experimentally found to be strongly affected by all of the above parameters. The optimum values of initial solution pH, photocatalyst concentration, and sacrificial reagent concentration, as well as the appropriate type of sacrificial reagent, were obtained. The results showed that the utilization of the photocatalyst with the proper selection of optimum operational conditions could lead to considerably high photocatalytic hydrogen evolution activity.  相似文献   

16.
Photocatalytic hydrogen generation is one of the most promising solutions to convert light energy into green chemical energy. In the present work, methoxy ethyl methyl imidazolium methyl sulphonate ionic liquid is used for the synthesis of i-TiO2 nanoparticles via ionothermal method at 120 °C. The obtained products were characterized by various spectroscopic techniques like XRD, FTIR, Raman, UV–visible, DRS, TEM and TG-DSC analysis. XRD pattern confirmed the anatase phase with minor rutile phase having average crystallite size of 5 nm. From the FTIR spectrum, the band appeared at ~547 cm?1 confirmed the Ti–O–Ti stretching and also few bands of ionic liquid. UV–vis spectrum clearly reveals the blue shift due to size effect of TiO2. The spherical surface structure and particle size (15–30 nm) have been studied in detail using TEM images. Finally, the practical applicability of the as synthesized i-TiO2 nanoparticles is shown by using it as a photocatalyst towards the generation of H2 through water splitting reaction and it is found to be 462 μmol h?1g?1.  相似文献   

17.
Quality of interfaces is a key factor determining photoexcited charge transfer efficiency, and in turn photocatalytic performance of heterostructure photocatalysts. In this paper, we demonstrated CdS-MoS2/RGO-E (RGO-E: reduced graphene oxide modified by ethylenediamine) nanohybrid synthesized by using a facile one-pot solvethermal method in ethylenediamine, with CdS nanoparticles and MoS2 nanosheets intimately growing on the surface of RGO. This unique high quality heterostructure facilitates charge separation and transportation, and thus effectively suppressing charge recombination. As a result, the CdS-MoS2/RGO-E exhibits a state-of-the-art H2 evolution rate of 36.7 mmol g?1 h?1 and an apparent quantum yield of 30.5% at 420 nm, which is the advanced performance among all the same-type photocatalysts (see Table S1), and far exceeding that of bare CdS by higher than 104 times. This synthesis strategy gives an inspiration for the synthesis of other compound catalysts, and higher performance photocatalyst may be obtained.  相似文献   

18.
MoS2 is a promising electrocatalyst for hydrogen evolution reaction and a good candidate for cocatalyst to enhance the photoelectrochemical (PEC) performance of Si-based photoelectrode in aqueous electrolytes. The main challenge lies in the optimization of the microstructure of MoS2, to improve its catalytic activity and to construct a mechanically and chemically stable cocatalyst/Si photocathode. In this paper, a highly-ordered mesoporous MoS2 was synthesized and decorated onto a TiO2 protected p-silicon substrate. An additional TiO2 necking was introduced to strengthen the bonding between the MoS2 particles and the TiO2 layer. This meso-MoS2/TiO2/p-Si hybrid photocathode exhibited significantly enhanced PEC performance, where an onset potential of +0.06 V (versus RHE) and a current density of −1.8 mA/cm2 at 0 V (versus RHE) with a Faradaic efficiency close to 100% was achieved in 0.5 mol/L H2SO4. Additionally, this meso-MoS2/TiO2/p-Si photocathode showed an excellent PEC ability and durability in alkaline media. This paper provides a promising strategy to enhance and protect the photocathode through high-performance surface cocatalysts.  相似文献   

19.
The photocatalytic activity for H2 evolution from pure water over Pd loaded TiO2 prepared by gardenia extract (Pd-Gardenia-TiO2) is systematically investigated. The as-prepared photocatalysts are characterized by X-ray diffraction, high resolution transmission electron microscopy, Fourier transform infrared spectra, and X-ray photoelectron spectroscopy. Gardenia extract functions as reducing and stabilizing agents simultaneously. The mean size of the as-prepared Pd nanoparticles is in the range of 2.3 ± 0.5 nm based on TEM images. The Pd-Gardenia-TiO2 catalyst exhibits good photocatalytic activity for H2 evolution (93 μmol · h−1 · g−1), which is much higher than that of Pd photodeposited on TiO2. Possible factors for its photocatalytic activity from pure water are also investigated.  相似文献   

20.
SnO2, a promising candidate for photocatalytic water splitting, displays poor activity due to insufficient light utilization and rapid electron-hole recombination of charge carriers. Herein, one-dimensional heterostructures of SnO2/SnS2 nanotubes was designed and synthesized through a facile electrospinning followed by vulcanized method. The unique heterostructured SnO2/SnS2 could simultaneously promote photocarrier transport and suppress charge recombination through the uniquely coupled SnO2/SnS2 heterogeneous interface. Additionally, the optimized type-II heterostructure could also improve light absorption and weak the barrier of photocharge transfer. As a result, the SnO2/SnS2 exhibited excellent photocatalytic H2 evolution performance under simulated light irradiation with high H2 production rate of 50 μmol h?1 without the use of any noble metal co-catalyst, which is 4.2 times higher than that of pure SnO2 under the same condition.  相似文献   

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