Titanium Dioxide: From Engineering to Applications

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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Recent Advances in Synthesis and Applications of Carbon-Doped TiO2 Nanomaterials

Catalysts ◽

10.3390/catal10121431 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1431

Author(s):

Li Hua ◽

Zhengliang Yin ◽

Shunsheng Cao

Keyword(s):

Separation Efficiency ◽

Photogenerated Electron ◽

Wide Bandgap ◽

Electron Hole ◽

Doped Tio2 ◽

Carbon Doped ◽

Tio2 Lattice ◽

Promising Tool ◽

Tio2 Nanomaterials ◽

Catalytic Fields

TiO2 has been widely used as a photocatalyst and an electrode material toward the photodegradation of organic pollutants and electrochemical applications, respectively. However, the properties of TiO2 are not enough up to meet practical needs because of its intrinsic disadvantages such as a wide bandgap and low conductivity. Incorporation of carbon into the TiO2 lattice is a promising tool to overcome these limitations because carbon has metal-like conductivity, high separation efficiency of photogenerated electron/hole pairs, and strong visible-light absorption. This review would describe and discuss a variety of strategies to develop carbon-doped TiO2 with enhanced photoelectrochemical performances in environmental, energy, and catalytic fields. Emphasis is given to highlight current techniques and recent progress in C-doped TiO2-based materials. Meanwhile, how to tackle the challenges we are currently facing is also discussed. This understanding will allow the process to continue to evolve and provide facile and feasible techniques for the design and development of carbon-doped TiO2 materials.

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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 black TiO2/graphene composites with enhanced photocatalysis

10.21203/rs.3.rs-128642/v1 ◽

2020 ◽

Author(s):

Zhaoqing Li ◽

Zhufeng Liu ◽

Xiao Yang ◽

Peng Chen ◽

Lei Yang ◽

...

Keyword(s):

Visible Light ◽

Photocatalytic Performance ◽

Sol Gel ◽

Photogenerated Electron ◽

Catalytic Performance ◽

Attractive Potential ◽

Electron Hole ◽

Hole Recombination

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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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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Reduced graphene oxide encapsulated Cu2O with controlled crystallographic facets for enhanced visible-light photocatalytic degradation

Functional Materials Letters ◽

10.1142/s1793604717500345 ◽

2017 ◽

Vol 10 (04) ◽

pp. 1750034 ◽

Cited By ~ 3

Author(s):

Guosong Wu ◽

Qiuping Shen ◽

Houlin Yu ◽

Tingyu Zhao ◽

Congda Lu ◽

...

Keyword(s):

Graphene Oxide ◽

Visible Light ◽

Reduced Graphene Oxide ◽

Photocatalytic Performance ◽

Photogenerated Electron ◽

Electron Hole ◽

Photogenerated Electrons ◽

Reduced Graphene ◽

One Step ◽

Crystallographic Facets

The Cu2O/reduced graphene oxide (Cu2O/rGO) composites with effective crystallographic facet controlling of Cu2O crystals were fabricated through a simple one-step wet chemistry method. The crystallographic facet-dependent photocatalytic performance of Cu2O was confirmed, favoring the cuboctahedral Cu2O with {100} and {111} facets and a better photocatalytic activity when compared to cubic and octahedral ones. This was attributed to the slight difference of surface energy between {100} and {111} facets which served as a driving force to promote the separation of photogenerated electron–hole pairs. Moreover, the introduction of two-dimensional rGO sheets could accelerate the transfer of photogenerated electrons from Cu2O to rGO, which further promoted the separation of photogenerated electron–hole pairs and the degradation of methyl orange (MO) under visible-light irradiation. The cuboctahedral Cu2O/rGO composite exhibited a superb photocatalytic performance with the degradation percentage of MO about 97.6% after one periodic photocatalysis due to the synergistic effect of cuboctahedral Cu2O and rGO sheets, foreboding its potential application as photocatalyst.

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Preparation of graphene-TiO2 nanocomposite films and its photocatalytic performances on degradation of Rhodamine B

Pigment & Resin Technology ◽

10.1108/prt-02-2017-0019 ◽

2018 ◽

Vol 47 (1) ◽

pp. 79-85

Author(s):

Pei Qin ◽

Guobin Yi ◽

Xihong Zu ◽

Huan Wang ◽

Hongsheng Luo ◽

...

Keyword(s):

Titanium Dioxide ◽

Photocatalytic Performance ◽

Separation Efficiency ◽

Diffuse Reflectance Spectrum ◽

Photogenerated Electron ◽

Nanocomposite Films ◽

Nanorod Arrays ◽

X Ray Diffraction ◽

Electron Hole ◽

Content Type

Purpose The aim of this paper is to synthesize graphene-modified titanium dioxide (GR-TiO2) nanorod arrays nanocomposite films, so that these can enhance the photocatalytic properties of titanium dioxide and overcome the problem of difficult separation and recovery of photocatalysts. Design/methodology/approach The GR-TiO2 nanocomposite films were synthesized via hydrothermal method and spin-coating. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), ultraviolet–visible (UV-Vis) diffuse reflectance spectrum and Raman spectrum. The photocatalytic performance of the GR-TiO2 nanocomposite films for degrading Rhodamin B under ultraviolet (UV) was studied by a UV-Vis spectrophotometer. The photocatalytic enhancement mechanism of graphene was studied by photoelectrochemical analysis. Findings The introduction of graphene expanded the range of the optical response of TiO2 nanorod arrays, improving the separation efficiency of the photogenerated electron-hole pairs, and thus dramatically increasing its photocatalytic performance. Research limitations/implications A simple and novel way for synthesizing GR-TiO2 nanocomposite films has enhanced the photocatalytic performance of TiO2. Originality/value The photocatalyst synthesized is easy to separate and recycle in the process of photocatalytic reaction, so it is possible to achieve industrialization.

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Enhanced Visible-Light Photocatalytic Performance of SAPO-5-Based g-C3N4 Composite for Rhodamine B (RhB) Degradation

Materials ◽

10.3390/ma12233948 ◽

2019 ◽

Vol 12 (23) ◽

pp. 3948

Author(s):

Lingfang Qiu ◽

Zhiwei Zhou ◽

Mengfan Ma ◽

Ping Li ◽

Jinyong Lu ◽

...

Keyword(s):

Photocatalytic Activity ◽

Visible Light ◽

Redox Reactions ◽

Photocatalytic Performance ◽

Dye Degradation ◽

Thermal Polymerization ◽

Light Illumination ◽

Electron Hole ◽

Visible Light Illumination ◽

Visible Light Photocatalytic

Novel visible-light responded aluminosilicophosphate-5 (SAPO-5)/g-C3N4 composite has been easily constructed by thermal polymerization for the mixture of SAPO-5, NH4Cl, and dicyandiamide. The photocatalytic activity of SAPO-5/g-C3N4 is evaluated by degrading RhB (30 mg/L) under visible light illumination (λ > 420 nm). The effects of SAPO-5 incorporation proportion and initial RhB concentration on the photocatalytic performance have been discussed in detail. The optimized SAPO-5/g-C3N4 composite shows promising degradation efficiency which is 40.6% higher than that of pure g-C3N4. The degradation rate improves from 0.007 min−1 to 0.022 min−1, which is a comparable photocatalytic performance compared with other g-C3N4-based heterojunctions for dye degradation. The migration of photo-induced electrons from g-C3N4 to the Al site of SAPO-5 should promote the photo-induced electron-hole pairs separation rate of g-C3N4 efficiently. Furthermore, the redox reactions for RhB degradation occur on the photo-induced holes in the g-C3N4 and Al sites in SAPO-5, respectively. This achievement not only improves the photocatalytic activity of g-C3N4 efficiently, but also broadens the application of SAPOs in the photocatalytic field.

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