Enhanced photoelectrochemical performance of NiO-doped TiO2 nanotubes prepared by an impregnation–calcination method

To improve the photocatalytic activity of TiO2, a series of NiO–TiO2 nanotubes (NTbs) is prepared by impregnating TiO2 nanotubes in a solution of NiCl2·6H2O at different concentrations. Self-organized TiO2 nanotubes are prepared by a two-step anodization process. Scanning electron microscopy images show that large particle agglomerates are formed for higher precursor concentrations, and X-ray energy-dispersive spectroscopy results indicate that the atomic percentages of Ni in the NiO–TiO2 NTbs prepared with precursor concentrations of 100 and 300 mM are 1.95% and 4.23%, respectively. Electronic lifetime measurements show that the recombination rate of photogenerated electron–hole pairs is lower for NiO–TiO2 NTbs compared to that of TiO2. Specifically, the recombination rate of the sample prepared at 50 mM is the lowest, which is associated with the longest electron lifetime. Compared to unmodified TiO2 nanotubes, NiO–TiO2 NTbs exhibit improved results for the photocatalytic degradation of rhodamine B.

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Synthesis of Z-scheme g-C3N4/V2O5photocatalyst with high activity under visible light

Ministry of Science and Technology, Vietnam ◽

10.31276/vjst.63(11db).42-46 ◽

2021 ◽

Vol 63 (11) ◽

pp. 42-46

Author(s):

Hung Thanh Tung Mai ◽

◽

Thi Hong Ngoc Doan ◽

Ngoc Kim Tuyen Nguyen ◽

Minh The Do ◽

...

Keyword(s):

Diffuse Reflectance ◽

Diffuse Reflectance Spectroscopy ◽

Photogenerated Electron ◽

Catalytic Performance ◽

X Ray Diffraction ◽

Electron Hole ◽

X Ray ◽

Photocatalytic Activities ◽

Calcination Method ◽

The Individual

Direct Z-scheme g-C3N4/V2O5 photocatalysts were prepared through a sonication-assisted calcination method. The obtained samples were characterised by X-ray diffraction (XRD),Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS), Scanning electron microscope (SEM), andPhotoluminescence spectroscopy (PL). Oxidations of tetracycline hydrochloride (TC) were employed to evaluate the photocatalytic activities of the obtained g-C3N4/V2O5materials. Different weight ratios (5, 10, 15, and 20%) of g-C3N4/V2O5 loaded composites were prepared, in which a 15% (CV-15) loaded composite was found to show optimal catalytic performance for the reaction. The degradation conversation of TC has achieved approximately 79.67% in CV-15 after a 2-hour reaction. g-C3N4/V2O5 photocatalystwas more active than the individual g-C3N4 and V2O5 materials, which could be attributed to the efficient separation of photogenerated electron-hole pairs shown in the photocatalytic mechanism of TC degradation.

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The Transfer Direction of Photogenerated Electrons in BaTiO3/TiO2 and CaTiO3/TiO2

Australian Journal of Chemistry ◽

10.1071/ch18360 ◽

2018 ◽

Vol 71 (12) ◽

pp. 965

Author(s):

Lingfeng Ruan ◽

Rongying Jiang ◽

Jing Liu ◽

Song Liu

Keyword(s):

Photoelectron Spectroscopy ◽

Photogenerated Electron ◽

Tio2 Films ◽

X Ray Diffraction ◽

Electron Hole ◽

X Ray ◽

Photogenerated Electrons ◽

Microscopy Techniques ◽

Transfer Direction ◽

Physical Principles

BaTiO3/TiO2 and CaTiO3/TiO2 bilayer-type photocatalyst films have been prepared and characterised by X-ray diffraction, Raman, X-ray photoelectron spectroscopy, UV-vis, and scanning electron microscopy techniques. The photodeposition of silver was done to confirm the reduction positions of the titanate/TiO2 films. Silver deposited preferentially on the side of TiO2 for BaTiO3/TiO2 whereas on the side of CaTiO3 for CaTiO3/TiO2. These results imply that the direction of photogenerated electron transfer is coincident with the semiconductor physical principles. Upon exposure to light, electron–hole pairs are generated and subsequently separated by an internal electrostatic field in the titanate–TiO2 heterojunction.

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Preparation of g-C3N4/MoS2 Composite Material and Its Visible Light Catalytic Performance

10.21203/rs.3.rs-627855/v1 ◽

2021 ◽

Author(s):

Yu Fan ◽

Yan-ning Yang ◽

Chen Ding

Keyword(s):

Electron Microscopy ◽

Photocatalytic Activity ◽

Visible Light ◽

Photoelectron Spectroscopy ◽

Photogenerated Electron ◽

Catalytic Performance ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Calcination Method

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.

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Synthesis and photocatalytic activity of ZnO/CuO composite for the degradation of methyl blue under vilsible light iradiation

Vietnam Journal of Catalysis and Adsorption ◽

10.51316/jca.2020.056 ◽

2020 ◽

Vol 9 (3) ◽

pp. 94-100

Author(s):

Kim Nguyen Van ◽

Nga Nguyen Thi Viet ◽

Tuyen Vo Thi Thanh ◽

Vien Vo

Keyword(s):

Photocatalytic Activity ◽

Diffuse Reflectance ◽

Diffuse Reflectance Spectroscopy ◽

Photogenerated Electron ◽

Reflectance Spectroscopy ◽

X Ray Diffraction ◽

Electron Hole ◽

X Ray ◽

Microwave System ◽

Direct Formation

Composite ZnO/CuO was prepared by direct formation of ZnO from Zn(OOCCH3)2 precursor in the presence of CuO with the assistant of the microwave system. The obtained composite was characterized by X-Ray Diffraction (XRD) and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-vis DRS), which shows that the composite with a bandgap of 3.27 eV contains two components, ZnO and CuO. The photocatalytic activity of ZnO/CuO was assessed by the degradation of methylene blue (MB) in water under visible light, shows that the photocatalytic activity for the ZnO/CuO composite was remarkably improved compared to single ZnO and CuO. This result is attributed to the reduced recombination rate of photogenerated electron-hole pairs by the presence of CuO in the composite, therefore photocatalysis activity increases.

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Synthesis and Photocatalytic Properties of SnSe2/Se Heterojunction Films

NANO ◽

10.1142/s1793292018500455 ◽

2018 ◽

Vol 13 (04) ◽

pp. 1850045

Author(s):

Jing Li ◽

Hongxiao Zhao ◽

Yan Lei ◽

Qingyuan Yang ◽

Zhi Zheng

Keyword(s):

Dye Degradation ◽

Photogenerated Electron ◽

X Ray Diffraction ◽

Surface Layers ◽

Electron Hole ◽

X Ray ◽

Transient Photovoltage ◽

One Step ◽

Degradation Properties ◽

First Time

SnSe2/Se heterojunction films were successfully grown on fluorine-doped tin oxide (FTO) glass for the first time via a one-step solvothermal route using magnetron sputtered Sn metallic precursors, Se powders as selenium source, cyclohexanol as solvent and cyclohexanol as auxiliary solvent, respectively. The SnSe2/Se heterojunction films consisted of Se nanoparticles or nanorods cluster and SnSe2 network surface layers. The crystalline phase and morphology of SnSe2/Se films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), respectively. The photocatalysis measurements of the products for rhodamine Blue (RhB) demonstrated that SnSe2/Se heterojunction films revealed better dye degradation properties than SnSe2 nanosheet films due to the higher separation rates of photogenerated electron–hole pairs of SnSe2/Se heterojunction films, which can be confirmed by surface transient photovoltage (TPV) analyzer.

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Preparation of Magnetic Ni0.5Zn0.5Fe2O4/ZnO Nanocomposites and Their Photocatalytic Performances for Methylene Blue in Aqueous Solution

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.18876 ◽

2020 ◽

Vol 20 (12) ◽

pp. 7506-7515

Author(s):

Wei Huang ◽

Qing-Mei Yu ◽

Yan-Yan Wang ◽

Yue-Yang Xu ◽

Wei Zhou ◽

...

Keyword(s):

Methylene Blue ◽

Photocatalytic Activity ◽

Photogenerated Electron ◽

Diffuse Reflection Spectroscopy ◽

X Ray Diffraction ◽

Electron Hole ◽

X Ray ◽

Coprecipitation Process ◽

Size Of Particles ◽

The Fourier Transform

Magnetic Ni0.5Zn0.5Fe2O4/ZnO-R (NZFO/ZnO-R) nanocomposites are prepared via the rapid combustion-coprecipitation process, and they are characterized by the Fourier Transform Infrared Spectroscopy (FTIR), the X-ray Diffraction (XRD), the Scanning Electron Microscopy (SEM), the Energy Dispersive X-ray Detector (EDX), the Specific Surface Area (BET), the UV-vis Diffuse Reflection Spectroscopy (DRS), and the Vibrating Sample Magnetometer (VSM). The photocatalytic activity of NZFO/ZnO-R nanocomposites is assessed in ultraviolet light (365 nm) by decoloration of methylene blue (MB). The results show that the magnetic NZFO/ZnO-0.2 nanocomposites consist of particles and rods. The size of particles is 18 nm. The width and length of rods are 66 nm and 198 nm, respectively. NZFO/ZnO-0.5 nanocomposites have better photocatalytic performance than that of NZFO, ZnO and NZFO/ZnO-R (R = 0.2, 0.3, 0.4, 0.6, or 0.7) from the results. Through careful investigation of influencing parameters (the amount of catalysts, pH and concentration of MB solution), the degradation efficiency of MB is closely connected with the transparency of solution and surface charge of catalysts. The enhanced photocatalytic activity of NZFO/ZnO-0.5 nanocomposites can be ascribed to the matching band positions between ZnO and NZFO, which results in a low recombination between the photogenerated electron-hole pairs. The possible mechanism is proposed for the improved ultraviolet photocatalytic activity of NZFO/ZnO-0.5 nanocomposites.

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Constructing Two-Dimensional Carbonitride Carbon/Cuprous Oxide Nanoheterostructures Toward Enhanced Visible Light Photodegradation of Organic Pollutants

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2020.2816 ◽

2020 ◽

Vol 15 (7) ◽

pp. 819-830

Author(s):

Jie Zhang ◽

Jingzhi Tian ◽

Tao Jing ◽

Shuo Li ◽

Yong Ma ◽

...

Keyword(s):

Methyl Orange ◽

Visible Light ◽

Organic Pollutants ◽

Visible Light Irradiation ◽

Cuprous Oxide ◽

Recombination Rate ◽

Photogenerated Electron ◽

Two Dimensional ◽

Electron Hole ◽

Degradation Ability

Small specific surface area as well as fast recombination rate of photoelectron–hole pairs deteriorated the photocatalytic performances of carbonitride carbon (g-C3N4) in solving environmental pollution and energy crises. In this study, cuprous oxide (Cu2O) nanocubes grew on the g-C3N4 porous nanosheet to form a n–p nanoheterostructure. This unique structure of the prepared g-C3N4/Cu2O photocatalyst resulted in the photogenerated electron–hole pairs having enhanced separation rates. Under visible light irradiation, heterojunction degradation ability of methyl orange was significantly increased and its enhanced mechanism was systematically studied.

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Preparation of Visible Light Responsive Photocatalyst from Titanium Dioxide Nanotubes Modified with Antimony Trisulfide

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.792.98 ◽

2018 ◽

Vol 792 ◽

pp. 98-103

Author(s):

Narudon Saijaioup ◽

Puangrat Kajitvitchyanukul ◽

Apichon Watcharenwong

Keyword(s):

Titanium Dioxide ◽

Visible Light ◽

Anatase Phase ◽

Visible Region ◽

Light Response ◽

Ethanol Solution ◽

Halogen Lamp ◽

X Ray ◽

Self Organized ◽

Anodization Process

Titanium dioxide (TiO2) nanotubes with a highly ordered structure were grown by a self-organized anodization process. The photodeposition process was used to improve the visible light response of titanium dioxide (TiO2) nanotubes. The irradiation was carried out with 500 W halogen lamp for 1, 5, 15, 30 and 60 min in the mixed ethanol solution of antimony trisulfide (Sb2S3). The obtained samples were annealed at 250 °C for 30 min. The morphology of the fabricated sample was characterized by a field emission scanning electron microscope (FE-SEM). The phase of samples was determined by X- ray diffractometer (XRD). The weight percentages of a component in the sample were measured by X-ray fluorescence spectrometry (XRF). UV-Vis diffuse reflectance spectra (DRS) of the samples were recorded. All titanium dioxide (TiO2) nanotube samples prepared by anodization process were anatase phase. All composite titanium dioxide (TiO2) nanotube /Sb2S3samples were a crystalline phase. The percentage of Sb and S increase with increasing of photodeposition’s time. The increasing photodeposition of antimony trisulfide (Sb2S3) on titanium (TiO2) nanotubes from 1 to 60 min lead to increasing of photoabsorption property of the material in the visible region.

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Fe-Doped g-C3N4: High-Performance Photocatalysts in Rhodamine B Decomposition

Polymers ◽

10.3390/polym12091963 ◽

2020 ◽

Vol 12 (9) ◽

pp. 1963

Author(s):

Minh Nguyen Van ◽

Oanh Mai ◽

Chung Pham Do ◽

Hang Lam Thi ◽

Cuong Pham Manh ◽

...

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Recombination Rate ◽

High Performance ◽

Area Measurement ◽

Bet Surface Area ◽

Xenon Lamp ◽

Electron Hole ◽

X Ray

Herein, Fe-doped C3N4 high-performance photocatalysts, synthesized by a facile and cost effective heat stirring method, were investigated systematically using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurement, X-ray photoelectron (XPS), UV–Vis diffusion reflectance (DRS) and photoluminescence (PL) spectroscopy. The results showed that Fe ions incorporated into a g-C3N4 nanosheet in both +3 and +2 oxidation states and in interstitial configuration. Absorption edge shifted slightly toward the red light along with an increase of absorbance in the wavelength range of 430–570 nm. Specific surface area increased with the incorporation of Fe into g-C3N4 lattice, reaching the highest value at the sample doped with 7 mol% Fe (FeCN7). A sharp decrease in PL intensity with increasing Fe content is an indirect evidence showing that electron-hole pair recombination rate decreased. Interestingly, Fe-doped g-C3N4 nanosheets present a superior photocatalytic activity compared to pure g-C3N4 in decomposing RhB solution. FeCN7 sample exhibits the highest photocatalytic efficiency, decomposing almost completely RhB 10 ppm solution after 30 min of xenon lamp illumination with a reaction rate approximately ten times greater than that of pure g-C3N4 nanosheet. This is in an agreement with the BET measurement and photoluminescence result which shows that FeCN7 possesses the largest specific surface area and low electron-hole recombination rate. The mechanism of photocatalytic enhancement is mainly explained through the charge transfer processes related to Fe2+/Fe3+ impurity in g-C3N4 crystal lattice.

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Amorphous Co3S4 nanoparticle-modified tubular g-C3N4 forms step-scheme heterojunctions for photocatalytic hydrogen production

Catalysis Science & Technology ◽

10.1039/d0cy02009e ◽

2021 ◽

Author(s):

Yuanpeng Wang ◽

Xuqiang Hao ◽

Lijun Zhang ◽

Zhiliang Jin ◽

Tiansheng Zhao

Keyword(s):

Hydrogen Production ◽

Band Structure ◽

Recombination Rate ◽

Photogenerated Electron ◽

Electron Hole ◽

Photocatalytic Hydrogen Production

An effective method to reduce the recombination rate of photogenerated electron–hole pairs was developed by the construction of heterojunctions with rationally designed photocatalysts having a matched band structure.

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