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1.
A novel molybdenum disulfide (MoS 2) and graphitic carbon nitride (g-C 3N 4) composite photocatalyst was synthesized using a low temperature hydrothermal method. MoS 2 nanoparticles formed on g-C 3N 4 nanosheets greatly enhanced the photocatalytic activity of g-C 3N 4. The photocatalyst was tested for the degradation of methyl orange (MO) under simulated solar light. Composite 3.0 wt.% MoS 2/g-C 3N 4 showed the highest photocatalytic activity for MO decomposition. MoS 2 nanoparticles can increase the interfacial charge transfer and thus prevent the recombination of photo-generated electron–hole pairs. The novel MoS 2/g-C 3N 4 composite is therefore shown as a promising catalyst for photocatalytic degradation of organic pollutants using solar energy. 相似文献
2.
As an effective semiconductor catalyst, cadmium sulfide (CdS) is used in the field of split water hydrogen evolution because of its suitable band gap (~2.4 eV), good photocatalysis activity. However, the rapid recombination of photogenerated electron–hole pairs limits the application of CdS in the field of catalytic hydrogen evolution. Here, we synthesize a CdS/MoS 2 mixed-dimensional heterojunction by a simple hydrothermal method. In this process, CdS nanoparticles were supported on MoS 2 nanosheets, where MoS 2 acts as a loading platform and co-catalyst to improve the photocatalytic performance of CdS. A series of characterizations confirmed that CdS nanoparticles with a size of approximately 130 nm were uniformly grown on the surface of MoS 2 nanosheets. Photoelectrochemical (PEC) tests show that this CdS/MoS 2 mixed-dimensional heterojunction has enhanced photocatalysis hydrogen evolution activity, which is due to the CdS/MoS 2 mixed-dimensional heterojunction can promote the separation of photogenerated electron–hole pairs and positive synergy of MoS 2 nanosheets as a co-catalyst. In addition, a new electrically assisted method is used to enhance the photocatalytic activity, and the photocatalytic performance of the CdS/MoS 2 mixed-dimensional heterojunction is improved by nearly four times when a voltage of 0.6 V is applied. This phenomenon is attributed to the fact that providing an appropriate voltage can further promote the separation of photogenerated electron–hole pairs and rapid carrier mobility, thereby effectively improve the photocatalytic activity of the photocatalyst. This work provides a good guiding significance for the design and construction of high-performance hydrogen evolution catalysts. 相似文献
3.
Films and particles of MoS 2 on graphene (G) showing synergy for photocatalytic H 2 evolution due to the strong interaction between the two layered components have been obtained by pyrolysis at 900 °C under argon flow of ammonium alginate, films or powders, containing variable proportions of (NH 4) 2MoS 4. X-ray diffraction shows that under these conditions (NH 4) 2MoS 4 decomposes to MoS 2, while simultaneously alginate forms few layers G or graphitic carbon residues. Sonication of MoS 2–G powders in water produces exfoliation of the material leading to few-layers platelets of MoS 2–G heterostructures. MoS 2 is considered as an alternative of noble metals for H 2 evolution in dye-sensitized photocatalytic systems. In the present case, MoS 2–G heterostructures exhibit more than double photocatalytic activity for H 2 generation than pristine MoS 2 particles. 相似文献
4.
The development of heterostructured semiconductor photocatalysts makes a noteworthy advancement in environmental purification technology. In this work, a novel heterostructured Bi 2O 3−CeO 2−ZnO, fabricated by a combination of microwave-assisted hydrothermal and thermal decomposition methods, showed an enhanced photocatalytic activity for Rhodamine B (RhB) degradation under sunlight, as compared to pristine ZnO, Bi 2O 3, CeO 2, and commercial Degussa TiO 2-P25. The obtained products were thoroughly characterized by various techniques including X- ray powder diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), elemental color mapping, energy-dispersive X-ray spectroscopy (EDAX), Raman spectrometry, Fourier transform infrared (FT-IR) spectroscopy, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and photoluminescence (PL) spectroscopy. PXRD analysis reveals that the heterostructure has the monoclinic lattice phase of α-Bi 2O 3, the cubic phase of CeO 2 and the hexagonal wurtzite phase of ZnO. FE-SEM images show that Bi 2O 3−CeO 2−ZnO has an ordered mixture of nanorod and nanochain structures. EDAX, elemental color mapping, Raman and FT-IR analyses confirm the successful formation of the heterostructured Bi 2O 3−CeO 2−ZnO. The UV–Vis DRS results demonstrate that Bi 2O 3−CeO 2−ZnO exhibits wide visible-light photoabsorption in 400–780 nm range. Moreover, the reduction in PL intensity of the heterostructured Bi 2O 3−CeO 2−ZnO, when compared to the pristine Bi 2O 3, CeO 2, and ZnO, indicates enhanced charge separation. The study on the mechanism displayed that the improved photocatalytic activity of Bi 2O 3−CeO 2−ZnO could be attributed to (1) the efficient separation of photoinduced electrons and holes of the photocatalysts, caused by the vectorial transfer of electrons and holes among ZnO, CeO 2 and Bi 2O 3, and (2) the wide visible-light photoabsorption range. This study introduces a new class of promising sunlight-driven photocatalysts. 相似文献
5.
In this study, ZnO nanoparticles were successfully deposited on the surface of ZnMgAl–CO 3–LDHs microspheres to form ZnO/ZnMgAl–CO 3–LDHs heterojunction photocatalysts by coprecipitation process. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The results show that ZnO nanoparticles with diameters about 10–80 nm are tightly grown on the nanosheets of the ZnMgAl–CO 3–LDHs microspheres. Compared with the pristine ZnMgAl–CO 3–LDHs microspheres and pure ZnO, the photocatalytic activity of the heterojunction ZnO/ZnMgAl–CO 3–LDHs photocatalyst is significantly enhanced towards the degradation of phenol under UV light irradiation. The enhancement of the photocatalytic activity of the heterojunction catalysts can be ascribed to their improved light absorption property and the lower recombination rate of the photoexcited electrons and holes during the photocatalytic reaction. The optimal molar ratio of ZnO/ZnMgAl–CO 3–LDHs for the photocatalysis is 3. The heterojunction photocatalyst ZnO/ZnMgAl–CO 3–LDHs may be a promising photocatalyst for future application in water treatment due to its excellent performance in degradation of phenol. 相似文献
6.
Environment-friendly photocatalysts with wide spectral responses for water decontamination are currently in demand. Ternary iron–zinc–copper mixed oxides with various molar ratios of Fe 3O 4/CuO to ZnO and ternary mixed oxides incorporated on graphene were synthesized using sol–gel and hydrothermal methods. The physicochemical properties of these magnetically separable materials were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, infrared absorption spectroscopy, UV–Vis spectroscopy, vibrating sample magnetometry, and Brunauer–Emmett–Teller (BET) surface area analysis. Furthermore, their photocatalytic and adsorptive properties were investigated using methylene blue as a model organic pollutant. Owing to their higher specific surface area and saturation magnetization, the ternary mixed oxides incorporated on graphene served as better adsorbents and photocatalysts than those without graphene. The adsorption process followed a pseudo-second-order kinetic model and Langmuir adsorption isotherm model, with a maximum adsorption capacity of 68.03 mg/g. The ternary mixed oxide with an Fe 3O 4/CuO to ZnO molar ratio of 1:3 showed better photocatalytic activity under both UV and visible light irradiation, and the efficiency increased with increasing graphene incorporation in the photocatalyst. Moreover, the photocatalyst maintained high efficiency with repetitive use. Radical scavenging experiments revealed that holes were the predominant oxidative species involved in the photodegradation of methylene blue. Thus, these magnetically separable photocatalysts are effective for the removal of organic pollutants from wastewater. 相似文献
7.
Constructing multi-component photocatalyst is an efficient method to achieve high photocatalytic efficiency. In this work, CdS nanorods modified with NiS nanoparticles are first prepared to improve the photocatalytic performance, as no H 2 generates on single NiS or CdS catalyst from glucose solution. MoS 2 and NiP x, as the cocatalysts for H 2 production, are loaded on the surface of NiS/CdS composite. With step-by-step solvothermal synthesis, four components (CdS, NiS, Mo 2S, and NiP x) are fully combined in the NiP x/MoS 2/NiS/CdS nanorods, generating many intimate contact interfaces. Moreover the optimized NiP x/MoS 2/NiS/CdS performs a significantly increased photocatalytic activity, with H 2 production rate at 297 µmol h –1 g –1. The synergistic effects of heterostructure (NiS/CdS) and cocatalysts (MoS 2 and NiP x) are the main reasons in enhancing photocatalytic performance, which facilitate the separation of charge carriers and prolong their lifetimes. This work provides an effective strategy to design photocatalysts with multiple components and fast charge separation for highly efficient H 2 production. 相似文献
8.
As an efficient cocatalyst, the 2D MoS 2 is thought to be a promising substitute to noble metals in the hydrogen evolution reaction (HER). In the past few years, single and few‐layer MoS 2 nanosheets have attracted a wide range of concerns for HERs. In this paper, single crystalline ZnO nanowires and MoS 2 nanosheets are fabricated to form MoS 2 nanosheet/ZnO nanowire hybrid nanostructure to enhance the hydrogen photogeneration. The results show that the hybridization of ZnO with moderate MoS 2 loading could enhance the PEC activity by producing more electrons and holes and reducing their recombination. The synthesis of MoS 2/ZnO composites proposed an effective way to build low cost and highly active HER catalysts. Moreover, the study on MoS 2/ZnO composites sheds light to the deep insight into the mechanism of photoelectrocatalytic HERs. 相似文献
9.
The development of highly efficient and multifunctional composite photocatalysts for both energy conversion and environmental governance has obtained great concerns. Here, a novel CdIn 2S 4/TiO 2 (CIS/THS) hollow composite photocatalyst was firstly designed and synthesized via a facile in-situ growth process, where the CdIn 2S 4 nano-octahedra densely attached on the surface of TiO 2 hollow spheres to form the unique hybrid heterostructure. The as-synthesized CIS/THS heterojunctions exhibit much superior photocatalytic activities for hydrogen evolution and Methyl Orange (MO) decomposition in comparison to pure CdIn 2S 4 and TiO 2 hollow spheres. The experimental results display that the CIS/THS-3 sample with the 30 wt% of TiO 2 presents the optimal photocatalytic H 2 production efficiency and its generation rate is 3.38 and 2.56 times as high as those of pure TiO 2 and CdIn 2S 4. Besides, the as-synthesized CIS/THS-3 hybrid also possesses the best MO photodegradation performance and its rate constant is 11.43 and 8.34 times higher than those of pure TiO 2 and CdIn 2S 4. The enhanced photocatalytic activities can be assigned to the synergistic effect, optimized light-harvesting capacity and the formation of hybrid heterostructure for boosting interfacial charge transfer and separation. Furthermore, based on the trapping experiments and ESR analysis, the possible type-Ⅱ interface charge transport mechanism was also proposed. Our study may provide the direct guidance for constructing other hollow TiO 2-based composite photocatalysts with superior photocatalytic water splitting and degradation performances. 相似文献
10.
A series of novel TiO 2-BiOCl-ZnCr-Ex composites for use as photocatalysts were synthesized via a facile solvothermal process using an exfoliated ZnCr-LDH (ZnCr-Ex) and depositing BiOCl and TiO 2 sequentially on the surface of ZnCr-Ex. The composites were characterized by XRD, TEM, SEM-EDS and UV–vis diffuse reflectance spectroscopy. In these composites, the BiOCl nanosheets were deposited first on the surfaces of ZnCr-Ex and then the TiO 2 nanoparticles were dispersed on the surface of BiOCl-ZnCr-Ex material as were seen from SEM and TEM analyses. The photocatalytic degradation of Rhodamine B (RhB) indicated that the TiO 2-BiOCl-ZnCr-Ex composite showed much higher visible-light photocatalytic activity for degradation of RhB than TiO 2 alone, BiOCl alone or the BiOCl-ZnCr-Ex by itself. The possible mechanisms of photocatalytic activity were discussed. Moreover, the present composite photocatalysts exhibited satisfactory re-usability for at least three cycles. Because of the facile synthesis process, higher photocatalytic activity under visible light irradiation and satisfactory re-usability of these composites, they can be touted as potential catalysts for degradation of organic pollutants in wastewater treatment. 相似文献
11.
In the present study, we have fabricated a new Z-scheme BiFeWO 6/MoS 2 composite for photocatalytic elimination of organic contaminants from the waste-water. A series of BiFeWO 6/MoS 2 composites were obtained by changing the amounts of BiFeWO 6 from 1 to 10 mg through a facile hydrothermal method. The phase structures and morphologies of these BiFeWO 6/MoS 2 composites were analyzed by SEM, HR-TEM, XRD, UV–vis DRS, element mapping and XPS techniques. Afterward, the dye-degradation experiments were conducted for the removal of Rhodamine B (RhB) using as-obtained BiFeWO 6/MoS 2 composite samples under visible-light illumination to evaluate their photocatalytic activity. It is found that the BiFeWO 6/MoS 2 composites exhibited great photocatalytic behavior than the pure BiFeWO 6 and MoS 2 samples. In particular, the BiFeWO 6/MoS 2 composite with 5 mg of BiFeWO 6 showed a quickly complete photocatalyst degradation ability of RhB in 75 min with high photo-stability and reusability behavior. This superior catalytic response of BiFeWO 6/MoS 2 composite may be contributed by its high light harvesting capacity as well as fast separation and movement of photo-generated electron-hole pairs. This proposed BiFeWO 6/MoS 2 composite is a very promising photocatalyst for environmental remediation work. 相似文献
12.
In this work, coupled ZnO/SnO 2 photocatalysts were prepared in a rotating packed bed (RPB) via co-precipitation. The precursors of coupled ZnO/SnO 2 photocatalysts were formed from solutions of zinc sulfate, tin tetrachloride and sodium hydroxide. The calcinations of these precursors yielded coupled ZnO/SnO 2 photocatalysts. The effect of calcination temperature on the characteristics and photocatalytic activity of coupled ZnO/SnO 2 photocatalysts was studied. The photocatalytic activity of coupled ZnO/SnO 2 photocatalysts was evaluated using the photocatalytic decolorization of methylene blue. The experimental results reveal that coupled ZnO/SnO 2 photocatalysts that were obtained by calcination at 600 °C for 10 h were the most efficient in decolorizing methylene blue. 相似文献
13.
Novel photocatalysts based on silver (Ag), TiO 2, and graphene were successfully synthesized by microwave-assisted hydrothermal method. The prepared photocatalysts were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) specific surface area analysis, X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The influence of silver loading and graphene incorporation on photocatalytic hydrogen (H 2) production of as-prepared samples was investigated in methanolic aqueous solution under visible light irradiation (λ≥420 nm). The results showed that Ag–TiO 2/graphene composite had appreciably enhanced photocatalytic H 2 production performance under visible light illumination compared to pure TiO 2, Ag–TiO 2 and TiO 2/graphene samples. The enhanced photocatalytic hydrogen production activity of Ag–TiO 2/graphene composite under visible light irradiation could be attributed to increased visible light absorption, reduced recombination of photogenerated charge carriers and high specific surface area. This novel study provides more insight for the development of novel visible light responsive TiO 2− graphene based photocatalysts for energy applications. 相似文献
14.
The g-C3N4 nanosheet was prepared by calcination method, the MoS2 nanosheet was prepared by hydrothermal method. The g-C3N4/MoS2 composites were prepared by ultrasonic composite in anhydrous ethanol. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, and photoluminescence techniques were used to characterize the materials. The photocatalytic degradation of Rhodamine B (Rh B) by g-C3N4/MoS2 composites with different mass ratios was investigated under visible light. The results show that a small amount of MoS2 combined with g-C3N4 can significantly improve photocatalytic activity. The g-C3N4/MoS2 composite with a mass ratio of 1:8 has the highest photocatalytic activity, and the degradation rate of Rh B increases from 50 to 99.6%. The main reason is that MoS2 and g-C3N4 have a matching band structure. The separation rate of photogenerated electron–hole pairs is enhanced. So the g-C3N4/MoS2 composite can improve the photocatalytic activity. Through the active material capture experiment, it is found that the main active material in the photocatalytic reaction process is holes, followed by superoxide radicals. 相似文献
15.
In this work, a two-step synthesis route combining an electrospinning method and a hydrothermal process was used to prepare MoS 2/CNFs hybrid. CNFs was applied as the matrix for the nucleation and growth of MoS 2 nanosheets. In this hybrid, the crisscrossed MoS 2 nanosheets were randomly aligned and densely packed over the surface of CNFs. We probed the photocatalytic activity of MoS 2/CNFs hybrid to degrade rhodamine B (Rh B) in an aqueous solution under visible light irradiation. The hybrid displayed higher photodegradation performance relative to MoS 2 and mechanical mixture of MoS 2 with CNFs, with 67% Rh B completely degraded over 5 h-period. We attributed such enhancement in photocatalytic activity to the enhanced absorption property and electrical conductivity due to the synergy between MoS 2 and CNFs. The hybrid can furthermore be easily separated from the solution and reused for the subsequent photodegradation cycles. We verified the negligible loss in the photodegradation activity of MoS 2/CNFs hybrid towards Rh B during the three subsequent cycles. The high photocatalytic activity and recyclability of the hybrid render its practical application to degrade organic pollutants (i.e., dye compounds) in industrial wastewater. 相似文献
16.
TiO 2/MoS 2 composite was encapsulated by hydrophobic SiO 2 nanoparticles using a sol–gel hydrothermal method with methyltriethoxysilane (MTES), titanium tetrachloride (TiCl 4), and molybdenum disulfide (MoS 2) as raw materials. Then, a novel dual functional composite film with hydrophobicity and photocatalytic activity was fabricated on a glass substrates via the combination of polydimethylsiloxane adhesives and hydrophobic SiO 2@(TiO 2/MoS 2) composite particles. The influence of the mole ratios of MTES to TiO 2/MoS 2 (M:T) on the wettability and photocatalytic activity of the composite film was discussed. The surface morphology, chemical compositions, and hydrophobicity of the composite film on the glass substrate were investigated by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and water contact angle (water CA) measurements. The results indicated that the composite film exhibited stable superhydrophobicity and excellent photocatalytic activity for degradation of methyl orange (MO) even after five continuous cycles of photocatalytic reaction when M/T was 7:1. The water CA and degradation efficiency for MO remained at 154° and 94%, respectively. Further, the composite film showed a good non-sticking characteristic with the water sliding angle (SA) at about 4°. The SiO 2@(TiO 2/MoS 2) composite consisting of hydrophobic SiO 2 nanoparticles and TiO 2/MoS 2 heterostructure could provide synergistic effects for maintaining long-term self-cleaning performance. 相似文献
17.
Highly photosensitive ZnO/WO 3 photocatalysts were fabricated by wet impregnation of zinc oxide (ZnO) in different contents. Tungsten trioxide (WO 3) was synthesized by hydrothermal route. The presence of ZnO inhibited the crystallization of WO 3 and caused agglomeration of WO 3 nanoparticles surface. The formation of Zn-O-W linkage was studied by X-ray photoelectron emission (XPS) and Fourier transforms Infra-red spectra (FTIR). These linkages were responsible for red shift of absorption peak of composites as compared to individual ZnO and WO 3. The band gap was decreased due to incorporation of ZnO in WO 3 which promoted the separation of photo-generated carriers. As a result, ZnO/WO 3 composite showed extremely high efficiency for MO degradation in comparison with Degussa P25, pure ZnO and WO 3. 2.0% ZnO/WO 3 composite displayed the highest activity in photocatalytic decomposition of methyl orange (MO) dye. 相似文献
18.
TiO 2 particles supported on multi-walled carbon nanotubes (MWCNTs) were prepared using a sol–gel method to investigate their photocatalytic activity under simulated solar irradiation for the degradation of methyl orange (MO) in aqueous solution. The prepared composites were analyzed using XRD, SEM, EDS and UV–vis absorption spectroscopy. The results of this study indicated that there was little difference in the shape and structure of MWCNTs/TiO 2 composite and pure TiO 2 particles. The composite exhibited enhanced absorption properties in the visible light range compared to pure TiO 2. The degradation of MO by MWCNTs/TiO 2 composite photocatalysts was investigated under irradiation with simulated solar light. The results of this study indicated that MWCNTs played a significant role in improving photocatalytic performance. Different amounts of MWCNTs had different effects on photodegradation efficiency, and the most efficient MO photodegradation was observed for a 2% MWCNT/TiO 2 mass ratio. Photocatalytic reaction kinetics were described using the Langmuir–Hinshelwood (L–H) model. The photocatalyst was reused for eight cycles, and it retained over 95.2% photocatalytic degradation efficiency. Possible decomposition mechanisms were also discussed. The results of this study indicated that photocatalytic reactions with TiO 2 particles supported on MWCNTs under simulated solar light irradiation are feasible and effective for degrading organic dye pollutants. 相似文献
19.
The presence of gold nanoparticles (Au) on the zinc oxide (Zn)-titanium oxide nanotubus (TiNTs) composites to form the Z-scheme type photocatalysts has been investigated for photocatalytic reduction of CO 2 to methanol. In this study, the commercial titanium dioxide powder (P-25) was first treated under a strong basic environment and applied a hydrotherrmal method to systhsize TiNTs, and calcined to use as a support. Then, various ratios of ZnO and TiNTs from 0.1 to 0.5 were also prepared by hydrothermal method to form TiNTs-ZnO-X (TZ-X, X is equal to the ZnO/TiNTs weight ratio) composites, and 1 to 5 wt % of Au were impregnated on the TiNTs-ZnO support to form the ZnO–Au-TiNTs composite photocatalysts.The catalysts will be characterized by x-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible spectroscopy (UV–Vis) and photoluminescence spectroscopy (PL) techniques to determine the structures and morphology of the ZnO–Au-TiNTs composites. The catalytic results have revealed that the TZ-0.20–2 wt% Au catalyst has the best photocatalysis activity with a 7777.1μmole/(g-cat) (hr) CH 3OH production yield.The formation of the ZnO–Au-TiNTs Z-scheme type heterostructure results in an efficient electron transfer pathway and electron-hole separation inside the composite catalyst which lead to a highly efficient CO 2 reduction and excellent improvement in methanol yield. 相似文献
20.
The multifunctional air filter, which can provide low resistance to airflow, was prepared from polyacrylonitrile (PAN) nanofibers (NFs) by impregnating zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activity. Incorporation of ZnO NPs improved the surface roughness and electrostatic charge of electrospun NFs. The PAN/ZnO composite filter with 12 wt%-ZnO showed a filtration efficiency of 98.8% and a pressure drop of 48 Pa for 300 nm aerosol particles, resulting in a quality factor of 0.092 Pa −1. In addition, PAN/ZnO composite exhibited excellent photocatalytic activity in methylene blue (MB) decomposition at 100 and 70.2% efficiencies, respectively, under UV and visible light. 相似文献
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