scholarly journals Construction of Direct Z-Scheme Photocatalyst by Mg1.2Ti1.8O5 and g-C3N4 Nanosheets toward Photocatalytic H2 Production and Disinfection

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Sijia Gu ◽  
Dan Zhang ◽  
Shirong Luo ◽  
Heng Yang

Exploring a novel and efficient photocatalyst is the key research goal to relieve energy and environmental issues. Herein, Z-scheme heterojunction composites were successfully fabricated by loading g-C3N4 nanosheets (CN) on the surface of Mg1.2Ti1.8O5 nanoflakes (MT) through a simple sol-gel method followed by the calcination method. The crystalline phase, morphologies, specific surface area, and optical and electrochemical performance of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-disperse X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET), diffuse reflectance spectroscopy (DRS), and electrochemical measurements. Considering the suitable band structures of the components, the photocatalytic performance was evaluated by photocatalytic H2O splitting and photocatalytic inactivation of Escherichia coli (E. coli). Among the samples, MT/CN-10 (the molar percentage of melamine to as-obtained Mg-Ti gel was 10%) shows superior photocatalytic performance, which the average H2 production rate was 3.57 and 7.24 times higher than those of MT and CN alone. Additionally, the efficiency of inactivating Escherichia coli (E. coli) over MT/CN-10 was 1.95 and 2.06 times higher as compared to pure MT and CN, respectively. The enhancement of the photocatalytic performance was attributed to the advantages of the extremely negative conduction band (CB) of CN and the extremely positive valence band (VB) of MT, the enhanced light absorption, and more efficient photogenerated charge carrier separation.

2020 ◽  
Vol 20 (3) ◽  
pp. 1447-1453 ◽  
Author(s):  
De-Shuai Zhen ◽  
Xiao-Hu Luo ◽  
De Yang ◽  
Hong-Tao Zou ◽  
Er-Hu Xiong ◽  
...  

In present work, a novel Nd@TiO2 Nanocomposite, synthesized successfully by a facile sol–gel method, reveals significant light-activated antibacterial activity. The X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) show the anatase phase and globular shape of Nd@TiO2. UV-vis diffuse reflectance spectroscopy and low temperature N2 adsorption (BET) indicate Nd0.02@TiO2 has the narrow band gap (3.0 eV) and a high specific surface area (121.1 m2·g-1). Furthermore, the prepared Nd@TiO2 exhibits unprecedented higher photocatalytic activity than P25 TiO2. In water, Nd@TiO2 has higher inactivation against Escherichia coli (E. coli) bacteria under simulated solar light irradiation 70 min than TiO2, and the highest antibacterial efficiency (91.5%) of E. coli was achieved on Nd0.02@TiO2.


2018 ◽  
Vol 876 ◽  
pp. 15-19
Author(s):  
Jian Wen Shi ◽  
Dan Dan Ma ◽  
Ya Jun Zou

The meso-porous TiO2 and Sm-doped meso-porous TiO2 were synthesized by a sol-gel method. Polyethylene glycol, with different added content, was added as a structure-directing agent. The prepared meso-porous TiO2 was characterized by nitrogen adsorption, X-ray diffraction and ultraviolet-visible diffuse reflectance spectroscopy, and the photocatalytic performance was evaluated by the decomposition of methyl orange. The results revealed that PEG plays a key role in creating porous structure during the heat-treatment. The photocatalytic performance of TiO2 is improved by adding proper content PEG, and Sm-doping can further promote the photocatalytic performance.


2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Eric S. Agorku ◽  
Bhekie B. Mamba ◽  
Avinash C. Pandey ◽  
Ajay K. Mishra

A series of S/Gd3+-codoped TiO2photocatalysts were synthesized by a modified sol-gel method. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse reflectance spectroscopy, scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM)/energy-dispersive spectroscopy (EDS). Laboratory experiments with Indigo Carmine chosen as a model for organic pollutants were used to evaluate the photocatalytic performance of S/Gd3+-codoped TiO2under visible-light with varying concentrations of Gd3+ions in the host material. XRD and Raman results confirmed the existence of anatase phase TiO2with particle size ranging from 5 to 12 nm. Codoping has exerted a great influence on the optical responses along with red shift in the absorption edge. S/Gd3+-codoped TiO2showed significant visible-light induced photocatalytic activity towards Indigo Carmine dye compared with S-TiO2or commercial TiO2. TiO2-S/Gd3+(0.6% Gd3+) degraded the dye (ka= 5.6 × 10−2 min−1) completely in 50 min.


Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 943
Author(s):  
Katalin Majrik ◽  
Zoltán Pászti ◽  
László Korecz ◽  
Judith Mihály ◽  
Zoltán May ◽  
...  

The influence of the semiconductor microstructure on the photocatalytic behavior of Pt-PtOx/TiO2 catalysts was studied by comparing the methanol-reforming performance of systems based on commercial P25 or TiO2 from sol–gel synthesis calcined at different temperatures. The Pt co-catalyst was deposited by incipient wetness and formed either by calcination or high-temperature H2 treatment. Structural features of the photocatalysts were established by X-ray powder diffraction (XRD), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS), optical absorption, Raman spectroscopy and TEM measurements. In situ reduction of Pt during the photocatalytic reaction was generally observed. The P25-based samples showed the best H2 production, while the activity of all sol–gel-based samples was similar in spite of the varying microstructures resulting from the different preparation conditions. Accordingly, the sol–gel-based TiO2 has a fundamental structural feature interfering with its photocatalytic performance, which could not be improved by annealing in the 400–500 °C range even by scarifying specific surface area at higher temperatures.


2020 ◽  
Vol 993 ◽  
pp. 1391-1400
Author(s):  
Yu Quan Ren ◽  
Shi Yong Sun ◽  
Edward Opong Acheampong ◽  
Fa Qin Dong ◽  
Biao Biao Ma ◽  
...  

A one-step synthesis of visible light responsive diatomite/g-C3N4 composite material was prepared by impregnation-calcination method. The products were characterized by Scanning electron microscope, X-ray diffractometer, Ultraviolet diffuse reflectance spectroscopy, Fourier transform infrared spectrometer, and Photoluminescence spectrometer. The SEM results showed that g-C3N4 was successfully attached onto the surface of the diatomite. Also the composite materials were more light-responsive compared with the single phase material. The composite materials had a maximum degradation efficiency up to nearly 91.79%. The significant improvement in photocatalytic performance was due to the porous structure of diatomite, increase of contact area of carbon nitride.


Author(s):  
Henrique Gonçalves ◽  
Denilson Freitas ◽  
Emanuely Souza ◽  
Mauricio Melo ◽  
Johan Gonzalez-Moya ◽  
...  

Forming semiconductor heterojunction is promising for improved photocatalytic performance due to synergistic combination of the best properties of each material. The present study reports a simple hydrothermal strategy to form n-n heterojunction of Ta2O5 nanotubes and BiVO4 microstructures. The Ta2O5/BiVO4 heterojunctions were characterized by Raman spectroscopy, UV‑Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and their photocatalytic activity was evaluated by hydrogen production and photodegradation of methylene blue (MB) dye in aqueous medium under AM 1.5 G (100 mW cm‑2) condition. The heterojunctions have optical absorption in the visible region (200‑500 nm) with crystal structures defined as monoclinic for BiVO4 and orthogonal for Ta2O5. For MB photodegradation, the Ta2O5/BiVO4 obtained via hydrothermal route showed a photodegradation of 72.3%, compared to 28.3% presented by the sample produced through the mechanical mixture, with the maintenance of 86.4% of its photocatalytic performance after 3 cycles of photodegradation. For H2 production, hydrothermally prepared Ta2O5/BiVO4 generated 10.2 μmol g-1 of H2 in 3 h; while Ta2O5 nanotubes and mechanical Ta2O5/BiVO4 mixture shows 6.82 and 2.80 μmol g-1, respectively. The results suggest that Ta2O5/BiVO4 is a promising material for applications in photocatalysis, promoting sustainable energy production through hydrogen and for the treatment of effluents containing cationic dyes.


Separations ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 25
Author(s):  
Chukwuka Bethel Anucha ◽  
Ilknur Altin ◽  
Emin Bacaksız ◽  
Tayfur Kucukomeroglu ◽  
Masho Hilawie Belay ◽  
...  

Abatement of contaminants of emerging concerns (CECs) in water sources has been widely studied employing TiO2 based heterogeneous photocatalysis. However, low quantum energy yield among other limitations of titania has led to its modification with other semiconductor materials for improved photocatalytic activity. In this work, a 0.05 wt.% CuWO4 over TiO2 was prepared as a powder composite. Each component part synthesized via the sol-gel method for TiO2, and CuWO4 by co-precipitation assisted hydrothermal method from precursor salts, underwent gentle mechanical agitation. Homogenization of the nanopowder precursors was performed by zirconia ball milling for 2 h. The final material was obtained after annealing at 500 °C for 3.5 h. Structural and morphological characterization of the synthesized material has been achieved employing X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) N2 adsorption–desorption analysis, Scanning electron microscopy-coupled Energy dispersive X-ray spectroscopy (SEM-EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy (UV-vis DRS) for optical characterization. The 0.05 wt.% CuWO4-TiO2 catalyst was investigated for its photocatalytic activity over carbamazepine (CBZ), achieving a degradation of almost 100% after 2 h irradiation. A comparison with pure TiO2 prepared under those same conditions was made. The effect of pH, chemical scavengers, H2O2 as well as contaminant ion effects (anions, cations), and humic acid (HA) was investigated, and their related influences on the photocatalyst efficiency towards CBZ degradation highlighted accordingly.


2014 ◽  
Vol 809-810 ◽  
pp. 890-894
Author(s):  
Dan Li ◽  
Lian Wei Shan ◽  
Gui Lin Wang ◽  
Li Min Dong ◽  
Wei Li ◽  
...  

Boron-BiVO4 samples were synthesized by sol-gel method. They were characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction. Photocatalytic activity of the obtained BiVO4 samples was investigated through degrading methylene blue (MB). The results reveal that boron-BiVO4 catalysts have monoclinic scheelite structure. The BiVO4 and Co-BiVO4 photocatalysts were responsive to visible light. Co-BiVO4 photocatalyst showed higher photocatalytic activity than pure BiVO4, resulting in the significantly improved efficiency of degradation of MB.


2014 ◽  
Vol 609-610 ◽  
pp. 250-254
Author(s):  
Ya Bin Li ◽  
Jin Tian Huang ◽  
Yan Fei Pan

In the paper, the TiO2nanomaterials adopted the microcrystalline cellulose as the template by the template method and sol-gel method was prepared. Through the infrared spectrometer (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD), the surface morphology, composition and the type of the samples were characterized respectively. The influence of the macro morphology of TiO2photocatalytic performance to use the reaction of decolorization and degradation of methyl orange as model was analyzed. The results showed that TiO2which was produced by the template of sallix fiber was Rod-shaped and the average diameter size of nanocomposite structure was 20.592 nm, which can provide a new method of producing other morphology of TiO2.


2011 ◽  
Vol 399-401 ◽  
pp. 722-726 ◽  
Author(s):  
Jiang Ping Zhao ◽  
Xiao Ni Yang ◽  
Hao Zhang

In this paper, Cu-Ce/TiO2nano-particles, whose molar ratio account for 2%,2.5%,3%,3.5% and 4% respectively, were synthesized by sol-gel method, using Ti(C4H9O)4as the raw material, And the photocatalytic activities of the prepared samples were investigated by degrading formaldehyde gas under pure visible light through simulating indoor environment in the environmental test chamber. Moreover, X-Ray Powder Diffraction (XRD) and Ultraviolet-visible spectrophotometer were applied to analyze the crystallite size and optical properties of the samples. It is indicated that the sample of 2.5% performs best in the test. Besides, photocatalytic mechanism of co-doping of Cu-Ce was discussed.


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