Photocatalytic Oxidation Ability Research Articles

Improvement of visible light-induced photocatalytic performance by Cr-doped SrTiO3−carbon nitride intercalation compound (CNIC) composite

Novel organic−inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped SrTiO3–carbon nitride intercalation compound (CNIC) composite photocatalysts were synthesized. The composite photocatalyst was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence (PL) spectroscopy, and BET surface area analyzer. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange (MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. For maximizing the photodegradation activity of the composite photocatalysts, the optimal CNIC content was determined. The improved photocatalytic activity of the as-prepared Cr-doped SrTiO3–CNIC composite photocatalyst may be attributed to the enhancement of photo-generated electron–hole separations at the interface.

New insights into how Pd nanoparticles influence the photocatalytic oxidation and reduction ability of g-C3N4nanosheets

The Pd nanoparticles promoted photocatalytic oxidation and inhibited reduction ability of g-C3N4due to their different roles in different photocatalysis reactions.

Novel adsorption and photocatalytic oxidation for removal of gaseous toluene by V-doped TiO2/PU under visible light

In this study, V was used as a dopant to defect into the TiO2 lattice, leading to formation of Ti3+ and V4+ in the lattice. The presence of Ti3+ and V4+ introduced into the TiO2 lattice increased the electron–hole pair generation capacity and electron–hole pair separation efficiency of the TiO2, leading to enhancement of the photocatalytic activity of the photocatalyst. Porous polyurethane (PU) was used to immobilize the V-doped TiO2 by creating chemical bonds. The use of porous substrate contributed to the increased adsorption ability of the enhanced photocatalyst, as well as expanded its application for the removal of toluene from aerosols. Under dark conditions, the V-TiO2/PU only exhibited adsorption ability for toluene treatment in aerosol. Under visible light conditions, the V-TiO2/PU exhibited high photocatalytic oxidation ability for the removal of toluene in aerosol. The photocatalytic oxidation ability was found to depend on the V to TiO2 ratio. The optimal V content in V/TiO2 for enhancing the photocatalytic activity of TiO2 was determined to be 6wt%. Even under visible light irradiation, the 6% V-TiO2/PU sample could photocatalytically remove 80% of the toluene in 200-ppmV inlet gas, while 89.3% of the removed amount was mineralized into CO2 and H2O.

Enhanced visible light photocatalytic activity and oxidation ability of porous graphene-like g-C3N4 nanosheets via thermal exfoliation

Graphene-like porous g-C3N4 nanosheets were synthesized via direct pyrolysis of thiourea followed by a thermal exfoliation. With increased exfoliation temperature, the color of the resulting samples gradually became shallow, and the thickness and size of the layers were decreased. A formation mechanism involving layer-by-layer exfoliation coupled with layer splitting was proposed. The band structure of the g-C3N4 nanosheets was continuously tuned because of quantum size effect. Time-resolved decay spectra indicated that the radiative lifetime of charge carriers (τ1 and τ2) increased from 4.13 and 26.23ns for bulk g-C3N4 to 5.36 and 36.57ns for graphene-like g-C3N4 nanosheets. The g-C3N4 nanosheet samples were applied for visible light photocatalytic removal of NOx in air. The performance of porous g-C3N4 nanosheets was significantly enhanced with increased exfoliation temperature from 450 to 550°C. Moreover, photochemical and structural stability was well maintained after multiple reaction cycles. By monitoring the reaction intermediate NO2, it was found that the generation of NO2 was inhibited. The activity enhancement of graphene-like g-C3N4 nanosheets can be predominantly ascribed to the prolonged lifetime and improved photo-oxidation ability of charge carriers arising from the unique electronic structure. As the synthesis method for graphene-like g-C3N4 nanosheets with high a performance is simple, the g-C3N4 nanosheets can be envisioned to be applicable in environmental remediation and solar energy conversion.

Synthesis of BiVO4-g-C3N4 composite photocatalyst with improved visible light-induced photocatalytic activity

The novel visible light-induced carbon nitride (g-C3N4) and BiVO4 composite photocatalysts were obtained through a simple mixing-calcination method. The physical and photophysical properties of the BiVO4-g-C3N4 composites were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, high-resolution transmission electron microscopy (HRTEM), photoluminescent (PL) spectroscopy, and BET surface area measurements. Photocatalytic oxidation ability of the prepared samples was examined by studying the degradation of rhodamine B (RhB) as a target pollutant under visible-light irradiation. The composite photocatalysts exhibited an enhanced photocatalytic performance in degrading RhB. The optimal g-C3N4 content of the composite photocatalysts was determined for the photodegradation activity. The improved photocatalytic activity of the as-prepared composite photocatalyst may be attributed to the enhancement of photo-generated electron-hole separation at the interface.

Design of a neutral photo-electro-Fenton system with 3D-ordered macroporous Fe2O3/carbon aerogel cathode: High activity and low energy consumption

A novel three-dimensional ordered macroporous Fe2O3/CA cathode (3DOM–Fe2O3/CA) was fabricated by using self-assembled colloidal crystal template and proposed in solar photo-electro-Fenton (SPEF) process at neutral pH. 3DOM–Fe2O3/CA possessed 3D-ordered interconnecting marcopores (390–425nm) with a hollow “cylindrical tube” in the vertical direction. Compared to the traditional Fe2O3/CA electrode, the 3DOM–Fe2O3/CA presented higher photocatalytic and Fenton oxidation ability. The interconnecting macropores generated multiple scattering and slow-photon effect for increasing light harvesting efficiency, while the nice channels minimized tortuosity and provided much more efficient mass transport. Almost complete removal of 200mgL−1 imidacloprid was achieved in 2.5h with 3DOM–Fe2O3/CA. The dynamic analysis showed that the degradation of imidacloprid follows the pseudo-first order reaction. The apparent rate constant for 3DOM–Fe2O3/CA electrode is 0.326h−1, which 2 times higher than that of reference Fe2O3/CA electrode. The energy consumption was used more effectively in SPEF with 3DOM–Fe2O3/CA. EPR and radical trapping experiments revealed that the OH radicals were main oxidants in SPEF system and 3D-ordered macroporous favored the formation of OH. Besides, 3DOM–Fe2O3/CA electrode presented very low iron leaching (<1ppm) and retained high catalytic activity after consecutive runs.

Visible light-induced Cr-doped SrTiO3-g-C3N4 composite for improved photocatalytic performance

Novel visible light-induced Cr-doped SrTiO3-g-C3N4 composite photocatalysts were synthesized by introducing polymeric g-C3N4. The composite photocatalyst was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence (PL) spectroscopy and BET surface area measurements. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange (MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. The optimal g-C3N4 content for the photodegradation activity of the composite photocatalysts was determined. The as-prepared composite photocatalyst exhibits an improved photocatalytic activity due to enhancement of photo-generated electron-hole separation at the interface.

Noble Metal-Like Behavior of Plasmonic Bi Particles as a Cocatalyst Deposited on (BiO)2CO3 Microspheres for Efficient Visible Light Photocatalysis

Novel plasmonic Bi nanoparticles deposited in situ in (BiO)2CO3 microspheres (Bi/BOC) were fabricated via a one-pot hydrothermal treatment of bismuth citrate, sodium carbonate, and thiourea. Different characterization techniques, including XRD, SEM, TEM, XPS, UV–vis DRS, PL, time-resolved fluorescence spectra, and photocurrent generation, were performed to investigate the structural and optical properties of the as-prepared samples. The results indicated that the Bi nanoparticles were generated on the surface of (BiO)2CO3 microspheres via the in situ reduction of Bi3+ by thiourea. The Bi nanoparticle deposited (BiO)2CO3 microspheres were employed for the photocatalytic removal of NO in air under visible light irradiation, and the sample exhibited a drastically enhanced photocatalytic activity and oxidation ability. The highly enhanced activity was attributed to the cooperative contribution of the surface plasmon resonance (SPR) effect, the efficient separation of electron–hole pairs, and the prolonged lif...

Efficient visible light photocatalytic oxidation of NO in air with band-gap tailored (BiO)2CO3–BiOI solid solutions

Abstract In order to develop efficient visible light photocatalysts for air purification, three dimensional (3D) (BiO)2CO3/BiOI (BOC/BOI) solid solutions were synthesized by a template free method at room temperature. This environment benign route could avoid high temperature and reduce the production cost. The results indicated that the as-prepared hierarchical nanocomposites samples assembled with 2D nanosheets were solid solutions. The aggregation of nanosheets led to the formation of 3D hierarchical porous architecture. For the (BiO)2(CO3)x(I2)1−x solid solution with x = 0.5, 0.75, 0.95, the samples have down-lowered valence band (VB) and up-lifted conduction band (CB) in contrast to (BiO)2CO3. Compared with (BiO)2CO3 (3.14 eV), the (BiO)2(CO3)x(I2)1−x solid solution showed narrowed band gaps from 1.89 to 2.68 eV which are suitable for visible light excitation. The 3D (BiO)2(CO3)x(I2)1−x solid solutions displayed efficient photocatalytic activity and high durability toward photo-oxidation of NO (600 ppb) in air. The large surface areas, hierarchical structure, and tailed band-gap structure contributed to the efficient photocatalytic oxidation ability of (BiO)2(CO3)x(I2)1−x solid solution. As NO has very low solubility and NO2 has a large solubility in water. A high NO to NO2 conversion ratio is beneficial for NOx removal by aqueous absorption. The photo-oxidation products can be readily and inexpensively removed by alkaline aqueous absorption. This work could provide new insights into the design, synthesis and environmental application of hierarchical nanocomposites photocatalysts.

Synergistic photocatalytic oxidation and adsorption of elemental mercury by carbon modified titanium dioxide nanotubes under visible light LED irradiation

Abstract In this paper, carbon modified titanium dioxide nanotubes (hereafter denoted as CTNTs) were synthesized via a hydrothermal method, followed by ethanol washing and then heat-treatment steps. The physicochemical properties of CTNTs were investigated by XRD, BET, HR-TEM, TG-FTIR and UV–Vis spectra. The resultant CTNTs were then utilized for the removal of elemental mercury (Hg 0 ) under the irradiation of visible light LED. Experimental results revealed that the CTNTs had a good adsorption capability and photocatalytic oxidation ability for the removal of Hg 0 , particularly for the catalyst that was calcinated at 300 °C. We proposed that the activity promotion for the CTNTs was mainly attributed to three aspects: the abundant adsorption sites for Hg 0 , the well sustained nanotubes structure and the expanded light adsorption spectrum of CTNTs. Furthermore, the roles of influence factors such as empty bed retention time, O 2 concentration, SO 2 concentration and NO concentration, were investigated. The experimental results verified that white light LED lamp was a suitable light source for the application of photocatalytic oxidation process.

Preparation and characterization of titania- and organo-pillared clay hybrid photocatalysts capable of oxidizing aqueous bisphenol A under visible light

To develop solid material with both higher adsorption capacities for toxic organic compounds and effective photocatalytic oxidation ability for toxic organic compounds under visible-light irradiation, we attempted to hybridize cationic Cu-phthalocyanine derivatives (PABI) as photosensitizers with cetyltrimethylammonium/montmorillonite (CTA/Mt) containing TiO2 nanocrystals, and investigated both adsorption and photocatalytic abilities of prepared hybrid solid material for bis-phenol A (BPA) dissolved in aqueous media, which was one of endocrine disrupting chemicals. The prepared hybrid solid material could adsorb sufficient amount of BPA dissolved in aqueous media by hydrophobic interaction between BPAs and interlayer space of CTA/Mt. Moreover, it was found that the present hybrid solid material could photocatalytically decompose BPA molecules adsorbed within hybrid solid material under UV and/or visible light irradiation, and then, final products were CO2, H2O, and so on.

Novel visible light-induced g-C3N4/Bi2WO6 composite photocatalysts for efficient degradation of methyl orange

Novel visible light-induced g-C3N4/Bi2WO6 composite photocatalysts were synthesized by introducing polymeric g-C3N4. The obtained g-C3N4/Bi2WO6 products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, ultraviolet–visible diffuse reflection spectroscopy (DRS), and photoluminescence spectroscopy. The DRS results revealed that the g-C3N4/Bi2WO6 samples had a red shift and strong absorption in the visible light region. The photocatalytic oxidation ability of the novel photocatalyst was evaluated using methyl orange as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading methyl orange. The optimal g-C3N4 content for the photocatalytic activity of the heterojunction structures was determined. The synergic effect between g-C3N4 and Bi2WO6 was found to lead to an improved photo-generated carrier separation. Consequently, the photocatalytic performance of the g-C3N4/Bi2WO6 composites under visible light irradiation (λ>420nm) was enhanced. The possible photocatalytic mechanism of the composites was proposed to guide the further improvement of their photocatalytic activity.

Photocatalytic properties of titania nanostructured films fabricated from titania nanosheets

We examined the photochemical properties of well-ordered multilayer films of titania nanosheets prepared on quartz-glass substrate using the layer-by-layer deposition method. The photocatalytic decomposition of gaseous 2-propanol and bleaching of Methylene Blue dye under UV light illumination were measured to evaluate the photocatalytic oxidation ability. Photoinduced hydrophilicity was also studied by measuring the contact angle of water droplets on the film. The results indicated that titania nanosheets had good photoinduced hydrophilicity. The monolayer film of titania nanosheets showed almost identical activity compared with well investigated sol-gel derived anatase TiO(2) film, while its photocatalytic oxidation activity was low by more than an order of magnitude. This fact suggests that photoinduced hydrophilicity could not be explained simply in terms of the photocatalytic removal of hydrophobic organic species adsorbed on the surface. The photocatalytic oxidation activity and the photoinduced hydrophilic conversion rate decreased with increasing number of nanosheet layers, suggesting that photogenerated carriers produced in the internal part of the multilayer films can hardly diffuse to the surface layer. Photochemical properties of ultrathin anatase films obtained simply by heating the titania nanosheet films were evaluated as well, and also revealed high photoinduced hydrophilicity.