scholarly journals One-Step Synthesis of MoS2/TiSi2 via an In Situ Photo-Assisted Reduction Method for Enhanced Photocatalytic H2 Evolution under Simulated Sunlight Illumination

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 299 ◽  
Author(s):  
Chunyong Zhang ◽  
Aijuan Liu ◽  
Kezhen Li ◽  
Yukou Du ◽  
Ping Yang

A new MoS2/TiSi2 complex catalyst was designed and synthesized by a simple one-step in situ photo-assisted reduction procedure. The structural and morphological properties of the composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and ultraviolet-visible diffused reflectance spectroscopy (UV-vis DRS), which proved the formation of MoS2/TiSi2. MoS2/TiSi2 with optimized composition showed obviously enhanced photocatalytic activity and superior durability for water reduction to produce H2. The H2 generation rate over the MoS2/TiSi2 photocatalyst containing 3 wt % MoS2 reached 214.1 μmol·h−1·g−1 under visible light irradiation, which was ca. 5.6 times that of the pristine TiSi2. The improved photocatalytic activity of MoS2/TiSi2 could be related to the broad response spectrum, large visible light absorption, and synergies among MoS2 and TiSi2 that enhance photoexcited charge transfer and separation.

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650114 ◽  
Author(s):  
Dan Li ◽  
Jianwei Li ◽  
Caiqin Han ◽  
Xinsheng Zhao ◽  
Haipeng Chu ◽  
...  

Few-layered MoS2 nanostructures were successfully synthesized by a simple hydrothermal method without the addition of any catalysts or surfactants. Their morphology, structure and photocatalytic activity were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electrochemical impedance spectra and UV-Vis absorption spectroscopy, respectively. These results show that the MoS2 nanostructures synthesized at 180[Formula: see text]C exhibit an optimal visible light photocatalytic activity (99%) in the degradation of Rhodamine B owing to the relatively easier adsorption of pollutants, higher visible light absorption and lower electron–hole pair recombination.


2014 ◽  
Vol 898 ◽  
pp. 23-26
Author(s):  
Jing Li ◽  
Wei Sun ◽  
Wei Min Dai ◽  
Yong Cai Zhang

TiO2/SnS2 nanocomposite was synthesized via hydrothermal treatment of tin (IV) chloride pentahydrate, thioacetamide and TiO2 nanotubes in deionized water at 150 °C for 3 h. The structure, composition and optical property of the as-synthesized nanocomposite were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and UV-vis diffuse reflectance spectra, and its photocatalytic property was tested in the reduction of aqueous Cr6+ under visible-light (λ > 420 nm) irradiation. It was observed that TiO2 nanotubes exhibited no photocatalytic activity, whereas TiO2/SnS2 nanocomposite exhibited photocatalytic activity in the reduction of aqueous Cr6+ under visible-light (λ > 420 nm) irradiation.


2021 ◽  
Author(s):  
Yu Fan ◽  
Yan-ning Yang ◽  
Chen Ding

Abstract 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 (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-Vis), and photoluminescence (PL) 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. The photocatalytic mechanism was proposed through the active matter capture experiment.


2014 ◽  
Vol 496-500 ◽  
pp. 297-300 ◽  
Author(s):  
Bi Tao Liu ◽  
Liang Liang Tian ◽  
Ling Ling Peng

A series of composites of the high photoactivity of {001} facets exposed BiOCl and grapheme sheets (GS) were synthesized via a one-step hydrothermal reaction. The obtained BiOCl/GS photocatalysts were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy. The as-prepared BiOCl/GS photocatalyst showed enhanced photocatalytic activity for the degradation of methyl orange (MO) under UV and visible light (λ > 400 nm). The enhanced photocatalytic activity could be attributed to oxygen vacancies of the {001} facets of BiOCl/GS and the high migration efficiency of photo-induced electrons, which could suppress the charge recombination effectively.


Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 118 ◽  
Author(s):  
Hailong Wang ◽  
Longjun Xu ◽  
Chenglun Liu ◽  
Yuan Lu ◽  
Qi Feng ◽  
...  

A new composite magnetic photocatalyst, Bi5O7I/MnxZn1−xFe2O4, prepared by a hydrothermal-roasting method was studied. The photocatalytic properties of Bi5O7I/MnxZn1−xFe2O4 were evaluated by degradation of Rhodamine B (RhB) under simulated sunlight irradiation, and the structures and properties were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible light (UV-Vis) diffuse reflectance spectra (DRS), and a vibrating sample magnetometer (VSM). The results indicated that Bi5O7I/MnxZn1−xFe2O4 was an orthorhombic crystal, which was similar to that observed for Bi5O7I. Bi5O7I/MnxZn1−xFe2O4 consisted of irregularly shaped nanosheets that were 40–60 nm thick. The most probable pore size was 24.1 nm and the specific surface area was 7.07 m2/g. Bi5O7I/MnxZn1−xFe2O4 could absorb both ultraviolet and visible light, and the energy gap value was 3.22 eV. The saturation magnetization, coercivity and residual magnetization of Bi5O7I/MnxZn1−xFe2O4 were 3.9 emu/g, 126.6 Oe, and 0.7 emu/g respectively, which could help Bi5O7I/MnxZn1−xFe2O4 be separated and recycled from wastewater under the action of an external magnetic field. The recycling experiments revealed that the average recovery rate of the photocatalyst was 90.1%, and the photocatalytic activity was still more than 81.1% after five cycles.


NANO ◽  
2019 ◽  
Vol 14 (08) ◽  
pp. 1950096 ◽  
Author(s):  
Wen Gao ◽  
Chengjia Zhang ◽  
Sainan Cui ◽  
Qian Liang ◽  
Song Xu ◽  
...  

In this study, LaFeO3/ZnIn2S4 composites were synthesized via in situ synthesis. The composition, structure and optical absorption properties of LaFeO3/ZnIn2S4 were characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy, fluorescence spectroscopy (PL), Fourier Transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The photocatalytic activity of the LaFeO3/ZnIn2S4 photocatalyst was determined based on the degradation of methyl orange (MO). LaFeO3/ZnIn2S4 composites showed much better photocatalytic performance compared with pure LaFeO3 and ZnIn2S4. The enhanced photocatalytic performance was attributed to intimately contacted interfaces and charge transfer channels which can effectively transfer and separate the photogenerated charge carriers.


2018 ◽  
Vol 77 (5) ◽  
pp. 1441-1448 ◽  
Author(s):  
Yuejin Li ◽  
Xili Shang ◽  
Changhai Li ◽  
Xiaoming Huang ◽  
Jingjing Zheng

Abstract Novel visible-light-induced UiO-66/BiOI photocatalysts with a p–n junction structure have been prepared for the first time through a facile hydrothermal method. The prepared photocatalysts were characterized using the powder X-ray diffraction, high resolution transmission electron microscopy, scanning electron microscopy, UV–visible diffuse reflectance spectra, and N2 adsorption–desorption (Brunauer–Emmett–Teller) techniques respectively. The photodegradation performances of UiO-66/BiOI photocatalysts were evaluated by photodegrading salicylic acid under visible-light irradiation. The UiO-66/BiOI composites displayed much higher photocatalytic efficiencies than pure BiOI under visible light. When the content of UiO-66 was 5.2 wt%, the composite (UiO-66/BiOI-2) has the best photocatalytic activity. Most of the salicylic acid molecules can be degraded in 100 min. The degradation rate of UiO-66/BiOI-2 samples is higher than single BiOI and UiO-66. The enhanced photocatalytic performance of UiO-66/BiOI may be ascribed to the formation of p–n heterojunctions between BiOI and UiO-66, which facilitates the transfer and separation of the photogenerated charge carriers. After recycling of the photocatalyst for five times for the photodegradation of salicylic acid, more than 85% of salicylic acid could still be degraded in the fifth cycle, implying that the as-prepared photocatalysts are highly stable.


Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 579
Author(s):  
Xu Zhang ◽  
Min Cai ◽  
Naxin Cui ◽  
Guifa Chen ◽  
Guoyan Zou ◽  
...  

Black TiO2 with doped nitrogen and modified carbon (b-N-TiO2/C) were successfully prepared by sol-gel method in the presence of urea as a source of nitrogen and carbon. The photocatalysts were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, electron paramagnetic resonance (EPR), and UV-vis diffuse reflectance spectra (DRS). The doped nitrogen, introduced defects, and modified carbon played a synergistic role in enhancing photocatalytic activity of b-N-TiO2/C for the degradation of chlorophyll-a in algae cells. The sample, with a proper amount of phase composition and oxygen vacancies, showed the highest efficiency to degrade chlorophyll-a, and the addition of H2O2 promoted this photocatalysis degradation. Based on the trapping experiments and electron spin resonance (ESR) signals, a photocatalytic mechanism of b-N-TiO2/C was proposed. In the photocatalytic degradation of chlorophyll-a, the major reactive species were identified as OH and O2−. This research may provide new insights into the photocatalytic inactivation of algae cells by composite photocatalysts.


Author(s):  
Yaping Guo ◽  
Jianyang Sun ◽  
Hui Chang ◽  
Xu Zhao

A simple, effective and environmental-friendly method was adopted for enhancing the photocatalytic activity of g-C3N4 in the reduction of aqueous Cr(Ⅵ) under visible-light irradiation. The enhancement was achieved via treatment of g-C3N4 in organic solvent with addition of NaOH particles by ultrasonic process for two hours. The results demonstrated that the treated g-C3N4 exhibited much higher photocatalytic activity than pristine g-C3N4 in the reduction of Cr(VI) . Under visible light irradiation for 120 min, the reduced ratios of Cr(VI) with the initial concentration of 50 mg/L in the presence of the treated g-C3N4and pristine g-C3N4 were 100% and 37.1%, respectively. With the addition of fulvic acid, Cr(VI) was efficiently removed at 40 min. Based on the characterization results of the structures and other physiochemical properties of the treated g-C3N4 and pristine g-C3N4 by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and UV Vis diffuse reflectance, the possible reasons responsible for the enhanced photocatalytic activity of the treated g-C3N4 were proposed. The yield and mechanism of different exfoliation methods were compared by semi-quantitative method.


2013 ◽  
Vol 12 (05) ◽  
pp. 1350035 ◽  
Author(s):  
GENGPING WAN ◽  
GUIZHEN WANG

Bi 2 WO 6 microspheres constructed from nanosheets have been synthesized by a controllable solvothermal route in a large scale. The structure characterizations of the microspheres were investigated in detail by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). On the basis of XRD analysis and SEM observation of the products at different reaction time periods, a growth mechanism of Bi 2 WO 6 microspheres was proposed. UV-Visible diffuse reflectance (DR) spectrum of the prepared Bi 2 WO 6 microspheres demonstrates that they have absorption in the visible light region. The photocatalytic activity of Bi 2 WO 6 microspheres toward Rhodamine-B ( RhB ) degradation was investigated and the as-prepared products exhibited good photocatalytic activity in degradation of RhB under 300 W Xe lamp light irradiation.


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