Synthesis and characterization of black TiO2/graphene composites with enhanced photocatalysis

Abstract According to the composite design, a series of black TiO2/graphene composites were synthesized to improve its photocatalytic activity. TiO2 is generated in situ on the surface of graphene by a facile sol-gel method. The combination of graphene and TiO2 was beneficial for eliminating the opportunity of photogenerated electron-hole recombination due to the excellent conductivity of graphene. In the subsequent hydrogenation process, the self-doping Ti3+ was introduced accompanied by the crystallization of amorphous TiO2. The narrowed bandgap caused by self-doping Ti3+ enhanced the visible light absorption and make the composites appear black. Both of them improved the photocatalytic performance of the synthesized black TiO2/graphene composites. The band structure of the composite was analyzed by valence band XPS, revealing the reason for the high visible light catalytic performance of the composite. The results proved that the black TiO2/graphene composites synthesized show attractive potential for applications in environmental and energy issues.

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Construction of Ag3PO4/SnO2 Heterojunction on Carbon Cloth with Enhanced Visible Light Photocatalytic Degradation

Applied Sciences ◽

10.3390/app10093238 ◽

2020 ◽

Vol 10 (9) ◽

pp. 3238

Author(s):

Min Liu ◽

Guangxin Wang ◽

Panpan Xu ◽

Yanfeng Zhu ◽

Wuhui Li

Keyword(s):

Visible Light ◽

Photocatalytic Performance ◽

Separation Efficiency ◽

Photogenerated Electron ◽

Carbon Cloth ◽

Electron Hole ◽

Step Process ◽

Photogenerated Electrons ◽

Rapid Transfer ◽

Visible Light Photocatalytic

In this study, the Ag3PO4/SnO2 heterojunction on carbon cloth (Ag3PO4/SnO2/CC) was successfully fabricated via a facile two-step process. The results showed that the Ag3PO4/SnO2/CC heterojunction exhibited a remarkable photocatalytic performance for the degradation of Rhodamine B (RhB) and methylene blue (MB), under visible light irradiation. The calculated k values for the degradation of RhB and MB over Ag3PO4/SnO2/CC are 0.04716 min−1 and 0.04916 min−1, which are higher than those calculated for the reactions over Ag3PO4/SnO2, Ag3PO4/CC and SnO2/CC, respectively. The enhanced photocatalytic activity could mainly be attributed to the improved separation efficiency of photogenerated electron-hole pairs, after the formation of the Ag3PO4/SnO2/CC heterojunction. Moreover, carbon cloth with a large specific surface area and excellent conductivity was used as the substrate, which helped to increase the contact area of dye solution with photocatalysts and the rapid transfer of photogenerated electrons. Notably, when compared with the powder catalyst, the catalysts supported on carbon cloth are easier to quickly recycle from the pollutant solution, thereby reducing the probability of recontamination.

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Preparation and Photocatalytic Performance for Degradation of Rhodamine B of AgPt/Bi4Ti3O12 Composites

Nanomaterials ◽

10.3390/nano10112206 ◽

2020 ◽

Vol 10 (11) ◽

pp. 2206

Author(s):

Gaoqian Yuan ◽

Gen Zhang ◽

Kezhuo Li ◽

Faliang Li ◽

Yunbo Cao ◽

...

Keyword(s):

Visible Light ◽

Noble Metal ◽

Rhodamine B ◽

Photocatalytic Performance ◽

Bimetallic Nanoparticles ◽

Resonance Effect ◽

Visible Region ◽

Photogenerated Electron ◽

Pt Nanoparticles ◽

Electron Hole

Loading a noble metal on Bi4Ti3O12 could enable the formation of the Schottky barrier at the interface between the former and the latter, which causes electrons to be trapped and inhibits the recombination of photoelectrons and photoholes. In this paper, AgPt/Bi4Ti3O12 composite photocatalysts were prepared using the photoreduction method, and the effects of the type and content of noble metal on the photocatalytic performance of the catalysts were investigated. The photocatalytic degradation of rhodamine B (RhB) showed that the loading of AgPt bimetallic nanoparticles significantly improved the catalytic performance of Bi4Ti3O12. When 0.10 wt% noble metal was loaded, the degradation rate for RhB of Ag0.7Pt0.3/Bi4Ti3O12 was 0.027 min−1, which was respectively about 2, 1.7 and 3.7 times as that of Ag/Bi4Ti3O12, Pt/Bi3Ti4O12 and Bi4Ti3O12. The reasons may be attributed as follows: (i) the utilization of visible light was enhanced due to the surface plasmon resonance effect of Ag and Pt in the visible region; (ii) Ag nanoparticles mainly acted as electron acceptors to restrain the recombination of photogenerated electron-hole pairs under visible light irradiation; and (iii) Pt nanoparticles acted as electron cocatalysts to further suppress the recombination of photogenerated electron-hole pairs. The photocatalytic performance of Ag0.7Pt0.3/Bi4Ti3O12 was superior to that of Ag/Bi4Ti3O12 and Pt/Bi3Ti4O12 owing to the synergistic effect between Ag and Pt nanoparticles.

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Synthesis and characterization of Z-scheme heterostructure CoWO4/g-C3N4 as a visible-light photocatalyst for removal of organic pollutant

Vietnam Journal of Catalysis and Adsorption ◽

10.51316/jca.2021.029 ◽

2021 ◽

Vol 10 (2) ◽

pp. 59-63

Author(s):

Hai Pham Viet ◽

Anh Dao Thi Ngoc ◽

Viet Nguyen Minh ◽

Ha Tran Thi Viet ◽

Dang Do Van ◽

...

Keyword(s):

Visible Light ◽

Rhodamine B ◽

High Performance ◽

Organic Pollutant ◽

Photogenerated Electron ◽

Morphological Properties ◽

Electron Hole ◽

Visible Light Photocatalyst ◽

Photocatalytic Activities

In this study, direct Z–scheme heterostructure CoWO4/g-C3N4 was synthesized by a facile hydrothermal method. The structural, morphological properties of the prepared samples were characterised by XRD, SEM, UV–Vis and PL measurements. The as-obtained heterostructure CoWO4/g-C3N4 exhibited enhanced photocatalytic activities toward the degradation of Rhodamine B under visible light irradiation with 92% Rhodamine B removal after 80 minutes irritation, which exceeded pristine g-C3N4 and CoWO4. The enhanced photocatalytic performance ascribed to interfacial contact between g-C3N4 and CoWO4, thus further inhibiting the recombination of photogenerated electron/hole pairs. It is anticipated that the construction of Z–scheme heterostructure CoWO4/g-C3N4 is an effective strategy to develop high-performance photocatalysts for the degradation of organic pollutants in water.

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Synthesis and Photocatalytic Degradation Performance of g-C3N4/ CoAPO-5/rGO Ternary Composite

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.281.848 ◽

2018 ◽

Vol 281 ◽

pp. 848-853

Author(s):

Ling Fang Qiu ◽

Xiao Bin Qiu ◽

Zhi Wei Zhou ◽

Shu Wang Duo

Keyword(s):

Visible Light ◽

Carbon Nitride ◽

Photocatalytic Performance ◽

Doping Content ◽

Electron Mediator ◽

Electron Hole ◽

Obvious Effect ◽

Ternary Composite ◽

Hole Recombination ◽

Binary Composite

Graphitic carbon nitride is a promising photocatalyst for environmental purification, but the photocatalytic performance is limited significantly due to its narrow visible-light adsorption and high photo-reduced electron-hole recombination rate. This work developed a novel way to overcome the two defects and obtained obvious effect. CoAPO-5 was used to broaden visible-light adsorption range by conducting g-C3N4/CoAPO-5 binary composite. In further, rGO was integrated into the binary system to form novel ternary composite. rGO performs as a electron mediator, which can inhibit photo-reduced electron-hole recombination efficiently. The samples were characterized by XRD, SEM, PL, IR and DRS. The photocatalytic performances for degrading RhB (10mg/L) indicated that g-C3N4/CoAPO-5/rGO have much higher activity than g-C3N4/CoAPO-5 because of synergistic effect. When the doping content of rGO in g-C3N4/CoAPO-5 was 0.5%, the degradation efficiency was improved by 14%.

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Ag3PO4 Deposited on CuBi2O4 to Construct Z-Scheme Photocatalyst with Excellent Visible-Light Catalytic Performance Toward the Degradation of Diclofenac Sodium

Nanomaterials ◽

10.3390/nano9070959 ◽

2019 ◽

Vol 9 (7) ◽

pp. 959 ◽

Cited By ~ 7

Author(s):

Xiaojuan Chen ◽

Chunmu Yu ◽

Runliang Zhu ◽

Ning Li ◽

Jieming Chen ◽

...

Keyword(s):

Degradation Rate ◽

Performance Enhancement ◽

Separation Efficiency ◽

Diclofenac Sodium ◽

Sodium Stearate ◽

Photogenerated Electron ◽

Catalytic Performance ◽

Electron Hole ◽

In Situ Deposition

CuBi2O4/Ag3PO4 was synthesized through a combination of hydrothermal synthesis and an in situ deposition method with sodium stearate as additives, and their textures were characterized with XRD, XPS, SEM/HRTEM, EDS, UV-Vis, and PL. Then, the photodegradation performance of CuBi2O4/Ag3PO4 toward the degradation of diclofenac sodium (DS) was investigated, and the results indicate that the degradation rate of DS in a CuBi2O4/Ag3PO4 (1:1) system is 0.0143 min−1, which is 3.6 times that in the blank irradiation system. Finally, the photocatalytic mechanism of CuBi2O4/Ag3PO4 was discussed, which follows the Z-Scheme theory, and the performance enhancement of CuBi2O4/Ag3PO4 was attributed to the improved separation efficiency of photogenerated electron–hole pairs.

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In situ bubble template promoted facile preparation of porous g-C3N4 with excellent visible-light photocatalytic performance

RSC Advances ◽

10.1039/c5ra09645f ◽

2015 ◽

Vol 5 (78) ◽

pp. 63264-63270 ◽

Cited By ~ 23

Author(s):

Lei Shi ◽

Lin Liang ◽

Fangxiao Wang ◽

Mengshuai Liu ◽

Tao Liang ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Recombination Rate ◽

Photocatalytic Performance ◽

Electron Hole ◽

Facile Preparation ◽

Bubble Template ◽

Splitting Water ◽

Visible Light Photocatalytic

pg-C3N4 prepared through in situ bubble template showed large surface area and low recombination rate of photoinduced electron–hole pairs, leading to enhanced visible-light photocatalytic activity for degrading pollutants and splitting water to H2.

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Surface oxygen vacancy and defect engineering of WO3 for improved visible light photocatalytic performance

Catalysis Science & Technology ◽

10.1039/c8cy00994e ◽

2018 ◽

Vol 8 (17) ◽

pp. 4399-4406 ◽

Cited By ~ 35

Author(s):

Qi Liu ◽

Fengjiao Wang ◽

Huaxiang Lin ◽

Yanyu Xie ◽

Na Tong ◽

...

Keyword(s):

Oxygen Vacancy ◽

Visible Light ◽

Photocatalytic Performance ◽

Photogenerated Electron ◽

Vacancy Defect ◽

Surface Oxygen ◽

Defect Engineering ◽

Electron Hole ◽

Surface Oxygen Vacancy ◽

Visible Light Photocatalytic

Compared to the pristine WO3, the oxygen vacancy defect levels of the sub-stoichiometric WO3−X narrow the bandgap and promote the separation of photogenerated electron–hole pairs.

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A metal-free 3C-SiC/g-C3N4 composite with enhanced visible light photocatalytic activity

RSC Advances ◽

10.1039/c7ra06497g ◽

2017 ◽

Vol 7 (63) ◽

pp. 40028-40033 ◽

Cited By ~ 10

Author(s):

Hao Xu ◽

Zhixing Gan ◽

Weiping Zhou ◽

Zuoming Ding ◽

Xiaowei Zhang

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Light Absorption ◽

Carbon Nitride ◽

Photocatalytic Performance ◽

Photogenerated Electron ◽

Electron Hole ◽

Visible Light Absorption ◽

Metal Free ◽

Visible Light Photocatalytic

Insufficient visible light absorption and fast recombination of the photogenerated electron–hole pairs have seriously hampered the photocatalytic performance of graphitic carbon nitride (g-C3N4) up to now.

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Enhanced visible light photocatalytic activity of AgI/TiO2 composite fabricated by a grinding method

Water Quality Research Journal ◽

10.2166/wqrj.2019.037 ◽

2019 ◽

Vol 54 (3) ◽

pp. 257-264

Author(s):

Jin Xu ◽

Dasheng Gao ◽

Shuang Cui ◽

Xiaohua Wang ◽

Ningning Liu

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Active Sites ◽

Photocatalytic Performance ◽

Photogenerated Electron ◽

Active Species ◽

Electron Hole ◽

Grinding Method ◽

The Stability ◽

Visible Light Photocatalytic

Abstract Through a simple grinding method, AgI/TiO2 composites were successfully synthesized. The as-prepared AgI/TiO2 composites were used as photocatalysts for Rhodamine B (RhB) degradation under visible light irradiation and exhibited excellent photocatalytic performance. In the presence of composites, almost 100% RhB was decomposed after 60 min. The photocatalytic activity of AgI/TiO2-0.5 composite was optimal, which was 9.5 times higher than that of pristine TiO2, and 15.6 times higher than that of AgI. Moreover, experimental results revealed that the improved photocatalytic activity was not only ascribed to the loading AgI but also resulted from the method that enabled the exposure of more active sites in the composites. In addition, the intimate interfacial contact obtained by this method could also promote the efficient separation of photogenerated electron-hole pairs. Moreover, the possible photocatalytic active species and the stability of the photocatalyst were investigated in detail.

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Titanium Dioxide: From Engineering to Applications

Catalysts ◽

10.3390/catal9020191 ◽

2019 ◽

Vol 9 (2) ◽

pp. 191 ◽

Cited By ~ 62

Author(s):

Xiaolan Kang ◽

Sihang Liu ◽

Zideng Dai ◽

Yunping He ◽

Xuezhi Song ◽

...

Keyword(s):

Titanium Dioxide ◽

Visible Light ◽

Photocatalytic Performance ◽

Environmental Pollutants ◽

Photogenerated Electron ◽

Wide Bandgap ◽

Electron Hole ◽

Crystal Facet ◽

Tio2 Lattice ◽

Tio2 Nanomaterials

Titanium dioxide (TiO2) nanomaterials have garnered extensive scientific interest since 1972 and have been widely used in many areas, such as sustainable energy generation and the removal of environmental pollutants. Although TiO2 possesses the desired performance in utilizing ultraviolet light, its overall solar activity is still very limited because of a wide bandgap (3.0–3.2 eV) that cannot make use of visible light or light of longer wavelength. This phenomenon is a deficiency for TiO2 with respect to its potential application in visible light photocatalysis and photoelectrochemical devices, as well as photovoltaics and sensors. The high overpotential, sluggish migration, and rapid recombination of photogenerated electron/hole pairs are crucial factors that restrict further application of TiO2. Recently, a broad range of research efforts has been devoted to enhancing the optical and electrical properties of TiO2, resulting in improved photocatalytic activity. This review mainly outlines state-of-the-art modification strategies in optimizing the photocatalytic performance of TiO2, including the introduction of intrinsic defects and foreign species into the TiO2 lattice, morphology and crystal facet control, and the development of unique mesocrystal structures. The band structures, electronic properties, and chemical features of the modified TiO2 nanomaterials are clarified in detail along with details regarding their photocatalytic performance and various applications.

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