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1.
Cadmium sulphide nanorods-reduced graphene oxide-molybdenum sulphide(CdS-rGO-MoS2) composites were successfully synthesized using hydrothermal process for enhancing the interfacial contact between CdS nanorods and MoS2 layer. The good contact between CdS and MoS2 is important for improving the photocatalytic hydrogen (H2) evolution. The morphological and structural studies showed the production of highly pure CdS phase with nanorod-like structure dispersed on rGO-MoS2 layer. X-ray photoelectron spectroscopy (XPS) and Raman results confirmed the reduction of graphene oxide (GO) into reduced graphene oxide (rGO). The higher photocurrent density of CdS-rGO-MoS2 composites compared to CdS/MoS2 and the fluorescence quenching observed for this composite provided some evidence for an inhibition of electron-hole recombination, which leads to a longer life time of the photogenerated carriers. Fast electron transfer can occur from CdS nanorods by the bidimensionnel rGO area to MoS2 layer due to the intimate interfacial contact. Composite CdS-rGO-MoS2 with 20 wt% rGO was found to be the most effective photocatalyst for H2 evolution (7.1 mmol h?1g?1). The good photocatalytic performance arose from the positive synergistic effect between CdS, rGO and MoS2 elements.  相似文献   

2.
g-C3N4 (CN) has attracted extensive attention in photocatalysis field, but its weak visible light absorption and rapid charge recombination limit its application. In this, MoS2 and CoSx (ZIF67 derivatives) as cocatalyst grew on the surface of semiconductor CN in situ to construct CoSx/MoS2/CN double heterojunction. Then the activities of photocatalytic hydrogen evolution and degradation MB were researched. The hydrogen production rate of 5%CoSx/MoS2/CN-2 photocatalyst is 9800 μmol h?1 g?1 and is about 6.5 times as great as CN, 46 times than MoS2 and 98 times than CoSx, respectively. Under natural sunlight and simulated sunlight, the degradation efficiency of MB is 99.95% and 99.50% after 4 h, respectively. Catalyst characterizations have pointed out that CoSx/MoS2/CN catalyst has abundant active sites and larger specific surface area, which increase absorption of water and oxygen. At the same time, internal electric field and S vacancy enhance electrons transfer rate, which effectively inhibit the recombination of e?-h+. This work provides a new idea into the creation of steady, high-efficiency and continuable photocatalytic catalyst for visible light.  相似文献   

3.
Reduced graphene oxide (rGO) supported g-C3N4-TiO2 ternary hybrid layered photocatalyst was prepared via ultrasound assisted simple wet impregnation method with different mass ratios of g-C3N4 to TiO2. The synthesized composite was investigated by various characterization techniques, such as XRD, FTIR, Raman Spectra, FE-SEM, HR-TEM, UV vis DRS Spectra, XPS Spectra and PL Spectra. The optical band gap of g-C3N4-TiO2/rGO nanocomposite was found to be red shifted to 2.56 eV from 2.70 eV for bare g-C3N4. It was found that g-C3N4 and TiO2 in a mass ratio of 70:30 in the g-C3N4-TiO2/rGO nanocomposite, exhibits the highest hydrogen production activity of 23,143 μmol g?1h?1 through photocatalytic water splitting. The observed hydrogen production rate from glycerol-water mixture using g-C3N4-TiO2/rGO was found to be 78 and 2.5 times higher than g-C3N4 (296 μmol g?1 h?1) and TiO2 (11,954 μmol g?1 h?1), respectively. A direct contact between TiO2 and rGO in the g-C3N4-TiO2/rGO nanocomposite produces an additional 10,500 μmol g?1h?1 of hydrogen in 4 h of photocatalytic reaction than the direct contact between g-C3N4 and rGO. The enhanced photocatalytic hydrogen production activity of the resultant nanocomposite can be ascribed to the increased visible light absorption and an effective separation of photogenerated electron-hole pairs at the interface of g-C3N4-TiO2/rGO nanocomposite. The effective separation and transportation of photogenerated charge carriers in the presence of rGO sheet was further confirmed by a significant quenching of photoluminescence intensity of the g-C3N4-TiO2/rGO nanocomposite. The photocatalytic hydrogen production rate reported in this work is significantly higher than the previously reported work on g-C3N4 and TiO2 based photocatalysts.  相似文献   

4.
Perovskite type materials have high potential photocatalytic application towards both hydrogen energy generation and organic dye degradation due to their high stability and good reusability. Here, it is the first analysis of photocatalytic degradation of RhB and hydrogen energy evolution under visible light over MoS2/LaFeO3 nanocomposite. The physicochemical properties of the materials were characterized using a range of techniques such as XRD, TEM, XPS, FTIR, PL, photocurrent, etc. The optical properties of the nanocomposite show good absorption in UV-Vis spectra as compared to the bare LaFeO3. In this study, MoS2/LaFeO3 nanocomposite was synthesized through single step in situ hydrothermal processes with a narrow bandgap, enhanced photocatalytic application under visible light. This novel MoS2/LaFeO3 nanocomposite is an efficient and promising photocatalyst for both hydrogen energy evolution and organic dye degradation.  相似文献   

5.
Lead-free Cs2AgBiBr6 (CABB) double perovskite as a new-type photocatalytic material alternative to lead halide perovskites holds promise to implement the solar-H2 conversion, but the interior recombination of photo-generated carriers and thus low photocatalytic hydrogen evolution reaction (HER) rate of CABB restrict its further industrial applications. Herein, we report the composite fabrication of MoS2/CABB heterostructure for high-efficiency and durable photocatalytic HER by anchoring non-noble MoS2 onto CABB via a facile dissolution-recrystallization method. The optimized MoS2/CABB performs a visible-light HER rate of 87.5 μmol h?1 g?1 in aqueous HBr solution, ca. 20-fold compared to that of pure CABB (4.3 μmol h?1 g?1), and presents a discontinuous 500-h photocatalytic HER stability with no evident loss. The superb performance of MoS2/CABB can be ascribed to the kinetics-facilitated heterostructure consisting of stable CABB and MoS2. This work proposes a facile and versatile tactic to construct a low-cost Cs2AgBiBr6-based heterostructure for efficient and long-term photocatalytic HER.  相似文献   

6.
Photocatalytic water splitting has greatly stimulated as an ideal technique for producing hydrogen (H2) fuel by employing two renewable sources, i.e., water and solar energy. Here, we have adopted a facile hydrothermal approach for the successful synthesis of reduced graphene oxide (rGO) incorporated Fe/MgO nanocomposites followed by thermal treatment at inert atmosphere to investigate their ability for photodegradation and photocatalytic hydrogen evolution via water splitting. Transmission Electron Microscopy images of Fe/MgO-rGO nanocomposite ensured the distribution of Fe/MgO nanoparticles throughout rGO sheets. Notably, all rGO supported nanocomposites, especially the one, thermally treated at 500 °C at Argon (Ar) atmosphere has demonstrated significantly higher photocatalytic efficiency towards the photodegradation of a toxic textile dye, rhodamine B, than pristine MgO and commercially available Degussa P25 titania nanoparticles as well as other composites. Under solar irradiation, Fe/MgO-rGO (500) nanocomposite exhibited 86% degradation of rhodamine B dye and generated almost four times higher H2 via photocatalytic water splitting compared to commercially available P25 titania nanoparticles. This promising photocatalytic ability of the Fe/MgO-rGO(500) nanocomposite can be attributed to the improved morphological and surface features due to heat treatment at inert atmosphere as well as escalated charge carrier separation with increased light absorption capacity imputed to rGO incorporation.  相似文献   

7.
As a promising catalyst for solar hydrogen production, black phosphorus (BP) has received widespread attention due to variable band gaps, high carrier mobility, and strong light absorption performance. Herein, we use MoS2 as a cocatalyst to synthesize BP/MoS2 catalyst with polycrystalline BP to improve photocatalytic performance under visible light irradiation. A small amount of MoS2 can reduce the recombination of electron-hole pairs in the composite, increase carrier transport efficiency, and then improve photocatalytic performance. As expected, the 10/0.5 ratio of BP/MoS2 catalyst exhibits the highest photocatalytic hydrogen evolution performance with a hydrogen evolution rate of 575.4 μmol h?1 g?1, which is 2.5 times of pure BP. Based on the results above, a simple method is provided to synthesize low-cost black phosphorus-based photocatalysts.  相似文献   

8.
Chemical doping of reduced graphene oxide (rGO) oxide has been a major trend as photocatalyst and electrocatalyst owing to large number of active sites they bring in. In the present work ternary copper iron sulphide (Cu5FeS4) has been successfully synthesized using hydrothermal method and incorporated with rGO, N/rGO and B/rGO. The structural, morphological and compositional changes were analyzed using XRD, XPS, SEM, TEM and EDAX results respectively. The bandgap of the materials was confirmed using UV-DRS results. The photoluminescence (PL) spectra of the samples revealed the reduction of recombination with the presence of rGO and doped rGO. The photocatalytic studies of the composites were carried out using methylene blue(MB) as a model pollutant where CFS-N/rGO shows the highest degradation rate of 70%.The electrocatalytic tests were conducted in order to study the performance of the composites as catalyst for HER where CFS-N/rGO showed an enhanced activity with higher current density and lower Tafel slope.The higher Cdl value of CFS-N/rGO indicates the increased number of exposed active sites when doped with N/rGO. The results indicate a considerable amount of change in the photocatalytic and electrocatalytic properties of CFS when doped with rGO, B/rGO and N/rGO.  相似文献   

9.
The construction of heterojunction has been regarded as an effective way to promote photocatalytic H2 evolution activity, in which an intimately interfacial contact between the materials forming heterojunction is a positive effect on enhancing activity. Herein, a ternary 3D interconnected nanocomposite Ti3C2/MoS2/CdS was synthesized by a hydrothermal method. MoS2 nanosheet with a vertically aligned structure grew on the surface of multi-layered Ti3C2 to form 3D Ti3C2/MoS2 with tightly interfacial contact, which works as a cocatalyst for enhancing photocatalytic H2 evolution. CdS as a photocatalyst covered the surface of Ti3C2/MoS2 to absorb light energy. Benefitting to the synergistic effect between Ti3C2 and MoS2, the Ti3C2/MoS2 further accelerates electron transfer and inhibits the recombination of carriers. The H2 evolution rate of Ti3C2/MoS2/CdS reaches 15.2 mmol h?1 g?1 and the apparent quantum yield is 42.1% at λ = 420 nm. The result provides a useful insight for developing cocatalysts with new nanostructures via controlled interfacial engineering.  相似文献   

10.
This study demonstrates a high-performance visible-light-driven photocatalyst for water splitting H2 production. CdS nanorods (30 nm in diameters) with shorter radial transfer paths and fewer defects were prepared by a solvothermal method. To mitigate the recombination of electrons and holes, MoS2 nanosheets with rich active sites were modified on the surface of CdS nanorods by a room-temperature sonication treatment. The photocatalytic water splitting tests show that the MoS2/CdS nanocomposites exhibit excellent H2 evolution rates. The highest H2 evolution rates (63.71 and 71.24 mmol g?1h?1 in visible light and simulated solar light irradiation) was found at the 6% MoS2/CdS nanocomposites, which was 14.61 times and 13.39 times higher than those of the corresponding pristine CdS nanorods in visible light and simulate solar light irradiation, respectively. The apparent quantum efficiency (AQE) of the 6% MoS2/CdS nanocomposites at 420 nm was calculated to be 33.62%. The electrochemistry tests reveal that the enhanced photocatalytic activity is a result of extra photogenerated charge carries, greatly enhanced charge separation and transfer ability of the MoS2/CdS composites. This study may give new insights for the rational design and facile synthesis of high-performance and cost-effective bimetallic sulfide photocatalysts for solar-hydrogen energy conversion.  相似文献   

11.
Nanocomposites of C–Ta4+ co-doped NaTaO3 and reduced graphene oxide (C-NTO/rGO) with highly efficient photocatalytic activity were fabricated by a one-step solvothermal reaction. The optimum composites C-NTO/3rGO (with 3 wt% rGO) exhibited superior photocatalytic activity for the degradation of RhB over a mono-component counterpart under visible light irradiation. The photocatalytic efficiency was found to be as high as 97% for 90 min. Both XRD and XPS characterizations indicated that the doping of carbon into the NaTaO3 lattice leads to the reduction of Ta5+ to Ta4+. Furthermore, the co-doping significantly narrows the band gap (about 2.8 eV). Photo-luminescence (PL), time resolved transient PL decay spectra and photo-current results confirmed that photo-induced hole-electron pairs can be effectively separated resulting from the introduction of rGO. The synergistic effect of a decreased band gap and highly effective separation of photo-generated electrons and holes may be responsible for the enhanced photocatalytic activity of the fabricated nanocomposites. Both h+ and ?OH active radicals were found to be the key factors for the photo-decomposition process of RhB over the nanocomposites, while ?O2? was also involved to a smaller extent. A possible photo-degradation mechanism for C-NTO/rGO was proposed on the basis of the experiments results.  相似文献   

12.
The CdS shows high selectivity on H2 for photocatalytic lactic acid decomposition. However, the low efficiency caused by ultrafast charge recombination was not well addressed. Herein, MoS2/CdS nanoheterostructure with intimate contact interface was synthesized in-situ and used as an efficient photocatalyst for H2 generation. The optimum H2 generation rate of MoS2/CdS is 45.20 mmol g?1 h?1 which significantly boosts the activity of CdS (0.27 mmol g?1 h?1) by more than 167 folds. Band alignment of MoS2 and CdS promoting charge transfer and separation contributes to the enhanced catalytic activity, which was well verified by multiple characterization approaches.  相似文献   

13.
The Thermal polycondensation method was used to make sulfur self-doped graphitic-carbon nitride (SCN) sheets that were anchored with samarium vanadate (SmV). The decorating of SmV nanoparticles on sheets of SCN is confirmed by X-ray diffraction, spectroscopic, and microscopic characterizations. When compared to the bandgap of pure SmV (2.16 eV) and SCN (2.44 eV), SmV decorating decreased the bandgap of SCN to 1.89 eV. The lowered bandgap in SmV/SCN and the formation of type II heterostructure resulted in improved performance in photoelectrochemical and photochemical hydrogen evolution and photocatalytic degradation experiments. The amount of hydrogen evolution was high in SmV/SCN which was found to be 22,618 μmol g?1 of H2 in 4 h under photochemical conditions. The obtained onset potential at 10 mA cm2 is ?190 mV under photoelectrochemical studies. The SmV/SCN was able to absorb visible light and degraded Methyl orange (MO). The reaction conditions were thoroughly optimized, found pH 8, 10 mg L?1 initial concentration of dye and 25 mg of SmV/SCN as an optimum condition under visible light. The degradation efficiency was up to 90% in just 80 min. Scavenger investigations were used to identify the active species (OH. and . O2?) and indicate which were then confirmed by electron spin resonance spectroscopic (ESR) experiments. The mechanism of photocatalysis has been well explored. The obtained results show that the SmV/SCN nanocomposite is capable of serving a choice of material for energy and environmental applications.  相似文献   

14.
Exploiting an inexpensive and high-effective composite catalyst for electrocatalytic hydrogen evolution and elimination of organic contaminant from wastewater has drawn great attentions recently. Herein, a facile two-step hydrothermal process was successfully adopted to realize the growth of MoS2 nanosheet on the surface of unique TNT@CNTs (TC). Remarkable, the optimized MoS2/TNT@CNTs (MTC) catalyst exhibited high-efficient photocatalytic activity for high concentrations (30 mg/L) of methylene blue (MB) and rhodamine B (RhB) with the photodegradation rate of 98.7% and 99.0% in 50 min, which are 2 and 6 times higher than that of pure TiO2 nanotube (TNT), respectively. Meanwhile, the novel composites also showed better hydrogen evolution reaction (HER) activity with the overpotential of 110 mV. The significant enhance in photocatalytic performance and electrocatalytic activity are attribute to formation of chemical bonds and large specific surface area, which effectively separate and transfer interfacial charges. The radical scavenging techniques confirmed that the holes (h+) and ?O2? radicals played a main role in the photocatalytic process. This study suggests that the novel nanocomposite has extensive application to solve environment and energy issues due to the low-cost raw materials, simple and inexpensive synthesizing process and environmental-friendly methods.  相似文献   

15.
Herein, we report the fabrication of type-II FeVO4/CuS heterojunction nanocomposite by a versatile reflux-assisted co-precipitation procedure. The hybrid FeVO4/CuS heterostructure with a band gap of 1.95 eV, demonstrated excellent degradation efficiency of ibuprofen antibiotic (~95%) after 90 min of visible-light irradiation, which displayed remarkably enhanced photocatalytic degradation (1.75 fold higher) in comparison to pristine FeVO4 structure. The superior photocatalytic performance of the FeVO4/CuS nanocomposite is associated with hierarchical flower-like architectures, great visible-light harvesting, and poor electron-hole recombination due to the fabrication of type-II heterojunction. In addition, we introduced an obvious photocatalytic destruction mechanism, which indicated that superoxides (?O2?) and holes (h+) were the invasive species in antibiotic degradation on the FeVO4/CuS photocatalyst. Consequently, the as-prepared FeVO4/CuS heterojunction photocatalyst is a promising candidate for the development of future photocatalysts towards the elimination of antibiotics under sun light irradiation at short process time.  相似文献   

16.
As a two-dimensional material, molybdenum disulfide (MoS2) exhibits great potential to replace metal platinum-based catalysts for hydrogen evolution reaction (HER). However, poor electrical conductivity and low intrinsic activity of MoS2 limit its application in electrocatalysis. Herein, we prepare a defective-MoS2/rGO heterostructures material containing 1T phase MoS2 and evaluate its HER performance. The experimental results shown that defective-MoS2/rGO heterostructures exhibits outstanding HER performance with a low overpotential at 154.77 mV affording the current density of 10 mA cm?2 and small Tafel slope of 56.17 mV dec?1. The unique HER performance of as-prepared catalyst can be attributed to the presence of 1T phase MoS2, which has more active sites and higher intrinsic conductivity. While the defects of as-prepared catalyst fully expose the active sites and further improve catalytic activity. Furthermore, the interaction between MoS2 and rGO heterostructures can accelerate electron transfer kinetics, and effectively ensure that the obtained catalyst displays excellent conductivity and structural stability, so the as-prepared catalyst also exhibits outstanding electrochemical cycling stability. This work provides a feasible and effective method for preparation of defective-MoS2/rGO heterostructures, which also supplies a new strategy for designing of highly active and conductive catalysts for HER.  相似文献   

17.
The construction of heterostructure is an effective strategy to synergetically couple wide-band-gap with the narrow-band-gap semiconductor with a mediate optical property and charge transfer capability. Herein, the Z-Scheme CdS/ZnSnO3 (CdS/ZSO) heterostructures were constructed by anchoring CdS nanoparticles on the surface of double-shell hollow cubic ZnSnO3 via the hydrothermal method. The direct recombination of excited electrons in the conduction band (CB) of ZSO and holes in the valence band (VB) of CdS via d-p conjugation at the interface greatly accelerated the internal electric field (IEF). The transfer mode follows the Z-Scheme mechanism, where CdS/ZSO synergistically facilitates the efficient charges transfer from CdS to ZnSnO3 through the intimate interface. Here, ZnSnO3 and CdS serve as an oxidation photocatalyst (OP) and reduction photocatalyst (RP), respectively. Thus, it can promote synergistically the oxidation half-reaction and reduction half-reaction of H2 evolution. The density-functional theory (DFT) calculation further confirms the charges transfer from CdS to ZnSnO3. The hydrogen evolution of 5% CdS/ZSO heterostructure reached 1167.3 μmol g?1, which was about 8 and 3 folds high compared to pristine ZSO (141.9 μmol g?1) and CdS (315.5 μmol g?1), during 3 h of reaction respectively. Furthermore, the CdS/ZSO heterostructures could suppress the photo corrosion of CdS, resulting in its high stability. This work is expected to enlighten the rational design of heterostructure for OP and RP to promote the hybrid heterostructures photocatalytic H2 evolution.  相似文献   

18.
Cu/TiO2 was modified by adding Rh as co-catalyst and used as a highly efficient photocatalyst for the hydrogen evolution reaction. A low amount of Rh was loaded onto Cu/TiO2 by the deposition-precipitation with urea (DPU) method to observe the effect on the hydrogen production displayed by different samples. The Rh–Cu/TiO2 oxide structure exhibited a remarkably high photocatalytic hydrogen evolution performance, which was about twofold higher than that of the Cu/TiO2 monometallic photocatalyst. This outstanding performance was due to the efficient charge carrier transfer as well as to the delayed electron-hole recombination rate caused by the addition of Rh. The influence of the different parameters of the photocatalyst synthesis and reaction conditions on the photocatalytic activity was investigated in detail. Hydrogen evolution was studied using methanol, ethanol, 2-propanol and butanol as scavengers with an alcohol:water ratio of 20:80. The methanol-water system, which showed the highest hydrogen production, was studied under 254, 365 and 450 nm irradiation; Rh–Cu/TiO2 showed high photocatalytic activity with H2 production rates of 9260, 5500, and 1940 μmol h?1 g?1, respectively. The Cu–Rh/TiO2 photocatalyst was active under visible light irritation due to its strong light absorption in the visible region, low band gap value and ability to reduce the electron (e?) and hole (h+) recombination.  相似文献   

19.
Here, we describe the in-situ synthesis of multicomponent ZnO-based photocatalysts for hydrogen production. We fabricated ZnO coupled with Cu–Cu2O nanoparticles and modified reduced graphene oxide (mRGO) to ameliorate hydrogen production. The simultaneous introduction of mRGO and Cu–Cu2O enhanced the generation rate of photocatalytic hydrogen to 3085.02 μmol g?1 h?1 due to significant alteration of the electronic structure. The bandgap energy of the prepared catalysts decreased from 3.2 eV for pristine ZnO to 2.64 eV for a composite containing 15% Cu–Cu2O. The optimal designed heterostructure efficiently separates photo charge carriers and prevents charge carriers’ recombination by accelerating charge transfer with the help of mRGO and metallic Cu and as a result leading to efficient hydrogen yields.  相似文献   

20.
There are many tremendous challenges to enhance the hydrogen evolution reaction (HER) activity of MoS2. In this study, nanoflower-like Co–MoS2/NiCoS structure supported on reduced Graphene Oxide (rGO) was rationally developed via a simple hydrothermal route, where the synergistic regulations of both interface structural and electronic conductivity were successfully presented by using controllable interface engineering and Co metal ions doped into MoS2 nanosheets. Ascribed to the 3D flower-like nanostructure with massive active sites, the interface coupling effect between MoS2 and Ni–Co–S phase, and Co-doped MoS2 can modulate its surface electronic density. The optimal Co–MoS2/NiCoS/rGO hybrid exhibits excellent HER activity in 1.0 M KOH, with a small overpotential (η10, 84 mV) at 10 mA cm?2 and a low Tafel slope (46 mV dec?1), accompanied by good stability. This work provides an effective route to produce other electrocatalysts based on interface structure and electronic conductivity engineering for HER in the future.  相似文献   

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