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Journal ArticleDOI

Highly active TiO2/g-C3N4/G photocatalyst with extended spectral response towards selective reduction of nitrobenzene

TL;DR: In this paper, a simple self-assembly photochemical reduction method has been proposed to prepare highly photocatalytic TiO 2 nanowire/g-C 3 N 4 nanosheet/graphene heterostructures.
Abstract: A simple self-assembly photochemical reduction method has been proposed to prepare highly photocatalytic TiO 2 nanowire/g-C 3 N 4 nanosheet/graphene heterostructures (TiO 2 /g-C 3 N 4 /G). In this hybrid structure, graphene enhances the charge transportation during photocatalytic process, and TiO 2 nanowires prevent graphene and g-C 3 N 4 from restacking. Meanwhile, g-C 3 N 4 with a more suitable band gap, extends the adsorption edge of the TiO 2 /g-C 3 N 4 /G composite to visual-region. Benefiting from the positive synergetic effect, 97% of nitrobenzene can be selectively reduced within 4 h by using TiO 2 /g-C 3 N 4 /G as the photocatalyst. The TiO 2 /g-C 3 N 4 /G composite with 3D structure demonstrates a great potential in selective oxidation and reduction of organics for the synthesis of high added-value organic compounds.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors present recent progress in the design and synthesis of carbonaceous-TiO 2 photocatalysts, covering carbon doping, activated carbon, fullerenes, carbon nanotubes and graphene.

275 citations

Journal ArticleDOI
TL;DR: In this article, a MIL-101(Fe)/g-C3N4 heterojunction was synthesized via in-situ growth of MIL- 101(Fe) onto g-C 3N4 surface and applied as a bifunctional photocatalyst for simultaneous reduction of Cr(VI) and degradation of BPA under visible light.
Abstract: Heterostructured composites with an excellent photocatalytic activity have attracted increasing attention because of their great application in environmental remediation. Herein, a MIL-101(Fe)/g-C3N4 heterojunction was synthesized via in-situ growth of MIL-101(Fe) onto g-C3N4 surface. The heterojunctions were applied as a bifunctional photocatalyst for simultaneous reduction of Cr(VI) and degradation of bisphenol-A (BPA) under visible light and exhibited an obvious enhancement in photocatalytic performance compared with MIL-101(Fe) or g-C3N4. The improved activity could be attributed to the enhanced light absorption and efficient charge carrier separation by forming a direct Z-scheme heterojunction with appropriate band alignment between MIL-101(Fe) and g-C3N4. The radical trapping and electron spin resonance showed that photo-generated electrons are responsible for the reduction of Cr(VI) and BPA degradation, following an oxygen-induced pathway. This work provides new insight into the construction of metal-free semiconductor/MOFs heterojunctions as a bifunctional visible-light-driven photocatalyst for efficient and simultaneous treatment of multiple toxic pollutants in water.

257 citations

Journal ArticleDOI
TL;DR: This review systematically complements the information that previous reviews have frequently ignored and points out the future development trends of g-C3N4-based heterojunction.
Abstract: The design of heterojunction with superior performance of light absorption and appropriate conduction band and valence band potentials is a promising approach for the applications in efficient environmental remediation and the solar energy storage. In recent years, many studies have been devoted to the applications of graphitic carbon nitride (g-C3N4)-based heterojunction photoactive nanomaterials under visible light irradiation due to its excellent physical, optical, and electrical properties, which inspired us to compile this review. Although many reviews demonstrated about the syntheses and applications of g-C3N4 composites, a targeted review on the systematic application and photocatalytic mechanisms of g-C3N4-based heterojunction, in which components are in intimate linkage with each other rather than a physical mixture, is still absent. In this review, the applications of g-C3N4-based heterojunction photoactive nanomaterials in environmental remediation and solar energy storage, such as photocatalyt...

240 citations

Journal ArticleDOI
TL;DR: In this article, a 2D/1D graphitic carbon nitride hybridized with titanate nanotubes (g-C3N4/TNTs) was prepared through a hydrothermal reaction-calcination method.
Abstract: 2D/1D graphitic carbon nitride hybridized with titanate nanotubes (g-C3N4/TNTs) was prepared through a hydrothermal reaction–calcination method. The photocatalyst exhibited high degradation efficiency for sulfamethazine (SMT) through photocatalysis under simulated solar light. The optimized material was composed of anatase, rutile, titanate and g-C3N4 crystalline phases. In situ transformation of titanate to anatase and rutile with specific content proportion (∼80:20, P25-type composition) leaded to formation of nanoscale “hot spots” at rutile–anatase–titanate interfaces, and then subsequent charge transfer occurred. Large specific surface area of TNTs as skeleton resulted in high-efficient interface reaction, while heterojunction with g-C3N4 further extended the adsorption to visible light region and retarded electron-hole pairs recombination. Density functional theory (DFT) calculation indicated the SMT sites with high Fukui nucleophilic (f-) index prefered to be attacked by radacils. Reduced toxicity of SMT degradation intermediates, good reusability and stability of g-C3N4/TNTs all suggested the great application potential in practical water treatment area.

197 citations

Journal ArticleDOI
TL;DR: In this paper, nitrogen doped g-C3N4 (NCN) with the extremely narrow band gap was prepared and applied for the photodegradation of phenols, which enhanced the absorption of visible light and further promoted the photocatalytic activity.
Abstract: In this work, nitrogen doped g-C3N4 (NCN) with the extremely narrow band gap was prepared and applied for the photodegradation of phenols. Experiments and DFT (the density functional theory) computation identified that N-doping introduced in the g-C3N4 matrix by substituting C atoms. DFT, PL (photoluminescence) spectra, optical property characteristic and PEC (photoelectrochemical) indicated that NCN possess extremely narrow band gap, efficient photogenerated carrier separation and the charge transfer, which enhanced the absorption of visible light and further promoted the photocatalytic activity. As a result, NCN(2:2) showed about twice higher photodegradation efficiencies and 3 times rate constant than pristine g-C3N4. The radical trapping experiments showed that •O2- radical and h+ served as crucial active species during the whole photodegradation reaction. This work can provide a strategy to enhance the photocatalytic activity of photocatalysts via introduce foreign atoms in matrix.

186 citations

References
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Journal ArticleDOI
27 Feb 2015-Science
TL;DR: The design and fabrication of a metal-free carbon nanodot–carbon nitride (C3N4) nanocomposite is reported and its impressive performance for photocatalytic solar water splitting is demonstrated.
Abstract: The use of solar energy to produce molecular hydrogen and oxygen (H2 and O2) from overall water splitting is a promising means of renewable energy storage. In the past 40 years, various inorganic and organic systems have been developed as photocatalysts for water splitting driven by visible light. These photocatalysts, however, still suffer from low quantum efficiency and/or poor stability. We report the design and fabrication of a metal-free carbon nanodot-carbon nitride (C3N4) nanocomposite and demonstrate its impressive performance for photocatalytic solar water splitting. We measured quantum efficiencies of 16% for wavelength λ = 420 ± 20 nanometers, 6.29% for λ = 580 ± 15 nanometers, and 4.42% for λ = 600 ± 10 nanometers, and determined an overall solar energy conversion efficiency of 2.0%. The catalyst comprises low-cost, Earth-abundant, environmentally friendly materials and shows excellent stability.

3,553 citations

Journal ArticleDOI
Hao Zhang1, Xiao-Jun Lv1, Yueming Li1, Ying Wang1, Jinghong Li1 
26 Jan 2010-ACS Nano
TL;DR: A chemically bonded TiO(2) (P25)-graphene nanocomposite photocatalyst with graphene oxide and P25, using a facile one-step hydrothermal method could provide new insights into the fabrication of a TiO (2)-carbon composite as high performance photocatalysts and facilitate their application in the environmental protection issues.
Abstract: Herein we obtained a chemically bonded TiO2 (P25)-graphene nanocomposite photocatalyst with graphene oxide and P25, using a facile one-step hydrothermal method. During the hydrothermal reaction, both of the reduction of graphene oxide and loading of P25 were achieved. The as-prepared P25-graphene photocatalyst possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously, which was rarely reported in other TiO2−carbon photocatalysts. Hence, in the photodegradation of methylene blue, a significant enhancement in the reaction rate was observed with P25-graphene, compared to the bare P25 and P25-CNTs with the same carbon content. Overall, this work could provide new insights into the fabrication of a TiO2−carbon composite as high performance photocatalysts and facilitate their application in the environmental protection issues.

2,944 citations

Journal ArticleDOI
03 Jul 2008-ACS Nano
TL;DR: The photocatalytic methodology not only provides an on-demand UV-assisted reduction technique but also opens up new ways to obtain photoactive graphene-semiconductor composites.
Abstract: Graphene oxide suspended in ethanol undergoes reduction as it accepts electrons from UV-irradiated TiO2 suspensions. The reduction is accompanied by changes in the absorption of the graphene oxide, as the color of the suspension shifts from brown to black. The direct interaction between TiO2 particles and graphene sheets hinders the collapse of exfoliated sheets of graphene. Solid films cast on a borosilicate glass gap separated by gold-sputtered terminations show an order of magnitude decrease in lateral resistance following reduction with the TiO2 photocatalyst. The photocatalytic methodology not only provides an on-demand UV-assisted reduction technique but also opens up new ways to obtain photoactive graphene-semiconductor composites.

2,397 citations

Journal ArticleDOI
TL;DR: Graphitic carbon nitride nanosheets are extracted via simple liquid-phase exfoliation of a layered bulk material, g-C3N4, to exhibit excellent photocatalytic activity for hydrogen evolution under visible light.
Abstract: Graphitic carbon nitride nanosheets are extracted, produced via simple liquid-phase exfoliation of a layered bulk material, g-C3N4. The resulting nanosheets, having ≈2 nm thickness and N/C atomic ratio of 1.31, show an optical bandgap of 2.65 eV. The carbon nitride nanosheets are demonstrated to exhibit excellent photocatalytic activity for hydrogen evolution under visible light.

2,137 citations

Journal ArticleDOI
30 Nov 2010-ACS Nano
TL;DR: It is proposed that TiO (2)-GR cannot provide truly new insights into the fabrication of TiO(2)-carbon composite as high-performance photocatalysts, hence offering a valuable source of reference on fabricating TiO(*(2))-carbon composites for their application as a photocatalyst in the environment cleanup.
Abstract: The nanocomposites of TiO2−graphene (TiO2−GR) have been prepared via a facile hydrothermal reaction of graphene oxide and TiO2 in an ethanol−water solvent. We show that such a TiO2−GR nanocomposite exhibits much higher photocatalytic activity and stability than bare TiO2 toward the gas-phase degradation of benzene, a volatile aromatic pollutant in air. By investigating the effect of different addition ratios of graphene on the photocatalytic activity of TiO2−GR systematically, we find that the higher weight ratio in TiO2−GR will decrease the photocatalytic activity. Analogous phenomenon is also observed for the liquid-phase degradation of dyes over TiO2−GR. In addition, the key features for TiO2−GR including enhancement of adsorptivity of pollutants, light absorption intensity, electron−hole pairs lifetime, and extended light absorption range have also been found in the composite of TiO2 and carbon nanotubes (TiO2−CNT). These strongly manifest that TiO2−GR is in essence the same as other TiO2−carbon (carb...

1,548 citations