•V doping was used to enhance the photocatalytic activity of TiO2 photocatalyst.•The enhanced TiO2 was fixed on porous polyurethane (PU) by chemical bonds.•The PU was used as a substrate to increase ...the adsorption ability of the photocatalyst.•V-TiO2/PU adsorbed and photocatalytically oxidized toluene gas under visible light.•The V/TiO2 ratio of 6wt% was optimal for enhancing the photocatalytic activity.
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.
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•Cu and V co-doping formed Ti3+ and oxy-vacancies in the TiO2 lattice.•The twin-metal co-doping enhanced the separation of TiO2’s electron–hole pairs.•The formed Ti3+ and ...oxy-vacancies enhanced both the adsorption and conversion of CO2.•The Cu@V-TiO2/PU converted CO2 into CH4 and CO even under visible light.•The optimal doping ratios of Cu/TiO2 and V/TiO2 were 2 and 4wt.%, respectively.
In this study, Cu and V co-doped TiO2 deposited on polyurethane (Cu@V-TiO2/PU) was synthesized as a catalyst for the reduction of CO2 with H2O vapor to preferentially produce CH4 as a valuable solar fuel under visible light. The Cu and V dopants defected into the TiO2 lattice, leading to the formation of Ti3+ and oxygen vacancies in the lattice. The Ti3+ formed in the doped TiO2 lattice created an intermediate band between the valence band and the conduction band of TiO2, leading to an increase in the electron–hole pair separation efficiency of TiO2. The oxygen vacancies existing on the surface of the photocatalyst could induce new adsorption sites to adsorb CO2. The generated electrons and holes reacted with the adsorbed CO2 and with H2O vapor to produce CO and primarily CH4. Therefore, the Cu@V-TiO2/PU photocatalysts successfully utilized visible light as the energy source and H2O vapor as a reductant to reduce CO2 to CO and CH4. The Cu@V-TiO2/PU photocatalysts also supplied sufficient electrons and holes for the selective reduction of CO2 to CH4 rather than CO. The 2Cu@4V-TiO2/PU photocatalyst, with Cu/TiO2 and V/TiO2 ratios of 2 and 4wt.%, respectively, exhibited the highest photocatalytic activity for CO2 conversion into solar fuels. The production rates of CH4 and CO produced from the CO2 reduction by the 2Cu@4V-TiO2/PU photocatalyst under visible light were 933 and 588μmolg−1cat.h−1, respectively.
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•Co-doping of TiO2 with Ag and V gained all the advantages of both V and Ag doping.•The optimal doping ratios of Ag/TiO2 and V/TiO2 were 4 and 2%, respectively.•The Ag@V-TiO2/PU ...exhibited very high electron-hole separation efficiency.•The Ag@V-TiO2/PU removed VOCs by both photocatalysis and adsorption.•The photocatalysis preferentially oxidized the high polarity organic compounds.
In this study, Ag and V co-doped TiO2 deposited on polyurethane (Ag@V-TiO2/PU) was for novel photocatalytic removal of gaseous volatile organic compounds (VOCs). The combination of V doping, which enhanced internal electron transfer in the TiO2 lattice, and Ag doping, which exhibited high internal electron transfer in the Ag2O and enhanced exterior electron transfer among Ag particles, Ag2O and TiO2, increased the photocatalytic activity of Ag@V-TiO2/PU for the removal of VOCs in aerosol. The surface area of this co-doped photocatalyst was also higher than that of the undoped and single-dopant photocatalysts. The optimal combination of weight ratios of Ag/TiO2 and V/TiO2 for maximizing the surface area and photocatalytic activity of TiO2 was 4 and 2%, respectively. Under visible light, the removal efficiency of individual hexane and butyl acetate gas by 4Ag@2V-TiO2/PU was 93.7 and 95.5%, respectively. The removed hexane and butyl acetate were mineralized into CO2 with ratios of 93.2 and 96.2%, respectively. The individual removal of hexane and butyl acetate gas by Ag@V-TiO2/PU was similar; however, in the mixture stream of both VOCs, much more butyl acetate than hexane was photocatalytically removed. This was associated with the much higher polarity of butyl acetate than that of hexane, so that the photocatalyst surface, where most of the oxy radicals were generated to oxidize the VOCs, was more occupied or covered by butyl acetate than by hexane.
In the study, Indium vanadate and Silver deposited on Graphitic carbon nitride (InVO4@Ag@g-C3N4) ternary heterojunction was successfully synthesized for advanced photocatalytic degradation of ...amoxicillin residue in aqueous environment. In the ternary heterojunction, silver metal generated plasmon resonance to effectively enhance electron-hole separation of both g-C3N4 and InVO4 components. Silver also acted as an electron mediator to improve its transfer from the InVO4 conduction band to the g-C3N4 valence band. Thus, the InVO4@Ag@g-C3N4 heterojunction effectively absorbed incident visible light to produce electrons at the conduction band of the g-C3N4 and holes at the valence band of the InVO4. These produced electrons exhibited high reduction potential to effectively react with O2 to form •O2− radicals, which could directly degrade amoxicilin or continuously oxidize H2O to produce •OH radicals for amoxicillin degradation. The photo-induced holes had high oxidation potential to degrade amoxicillin directly or to react with H2O to produce •OH radicals for effective degradation of the antibiotics. Thus, the synthesized InVO4@Ag@g-C3N4 ternary heterojunction showed advanced photocatalysis for degradation of amoxicillin. Finally, the recovered experiments indicated that the InVO4@Ag@g-C3N4 ternary heterojunction exhibited high stability and recycling ability during photocatalysis.
•Successfully created InVO4@Ag@g-C3N4 ternary heterojunction photocatalyst.•Plasmon resonance of Ag enhanced electron-hole separation of both g-C3N4 and InVO4.•Ag also improved electron transfer between interface of InVO4 and g-C3N4 components.•The InVO4@Ag@g-C3N4 showed novel photocatalytic amoxicillin degradation.
Photocatalytic degradation using TiO
2
is one of the most effective techniques for treating residual emerging compounds present in water. However, practical applications are limited since it only ...absorbs ultraviolet irradiation. Nitrogen and sulfur (N, S) co-doped TiO
2
nanomaterials (N,S-TiO
2
) were prepared by a controlled sol–gel method; the characterization and photocatalytic activity have been studied for the removal of ciprofloxacin antibiotic under UV–Visible light. The interstitial doping of nitrogen and sulfur substitute oxygen and titanium into the TiO
2
lattice, which increases the valence band and decreases the conduction band, respectively. The lowest value band-gap of 2.5 eV and the crystallite size of 5.13 nm compared to other available synthesis methods was observed on N,S-TiO
2
which allowed to broaden the light absorption to the visible region. The low level electron and hole recombination was related by the N, S doping. The optimal ciprofloxacin removal was obtained at pH 5.5, a dosage of 0.05 g, initial concentration of 30 mg L
−1
with a removal efficiency of 78.7%. A comparison of the effectiveness of antibiotic treatment of N,S-TiO
2
with synthetic TiO
2
and commercial TiO
2
was also made, taking the potential for regeneration into account. The photocatalytic degradation of ciprofloxacin catalyzed by N,S-TiO
2
was described by pseudo-first-order kinetics.
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•Successfully doped Cu into ZnO lattice to enhance its photocatalytic activity.•Cu dopant prevented recombination of photo-excited e− and h+ of the ZnO.•The Cu-ZnO exhibited excellent ...photocatalytic degradation of monocrotophos pesticide.•The optimal mole ratio of Cu/ZnO in the Cu-ZnO for degradation of monocrotophos was 3%.•The optimal pH for the photocatalytic degradation of monocrotophos was pH 7.
In the work, we successfully synthesized Cu doped ZnO materials for photocatalytic degradation of monocrotophos pesticide (MCP). The used Cu metal doped into the ZnO matrix created an intermediate band to excite electron from valence band (VB) to conduction band (CD) of the ZnO leading to increase in optical absorption, decrease in band gap as well as photocatalytic performance of the material. Hence, the synthesized photocatalyst showed intense activity for photocatalytic degradation of MCP into CO2, H2O and harmless inorganic ions even under visible radiation. We also investigated that the 3Cu-ZnO photocatalyst, which the weight ratio of Cu/ZnO was 3 wt%, showed the highest MCP degradation efficiency among these synthesized Cu-ZnO. The excess dopants tended to form CuO existing on ZnO surface. The formed CuO acted as a center for recombination of produced electrons and holes resulted in decrease in photocatalytic performance of the Cu-ZnO. Finally, we investigated that the optimal pH for the degradation of MCP by the synthesized Cu doped ZnO photocatalyst was pH 7.
Herein, Cu was incorporated into ZnO lattice to reduce its band gap as well as to extend its visible radiation response. The obtained Cu-ZnO was continuously integrated with g-C3N4 to create ...Cu-ZnO/g-C3N4Z-direct scheme photocatalyst for advanced atrazine removal. Radical scavenging experiments have been also conducted to clearly figure out photocatalytic mechanism for degradation of atrazine by the synthesized photocatalyst. The synthesized Cu-ZnO only utilized the generated h+ for atrazine degradation (direct and indirect via formation hydroxyl radicals (•OH)) and the g-C3N4 only utilized the generated e− for atrazine degradation (indirect via reaction with O2 to form superoxide anion, which needed to continuously react with H2O to form •OH). Therefore, the photocatalytic atrazine degradation by synthesized Cu-ZnO material was greater than that by synthesized g-C3N4 material. Cu-ZnO/g-C3N4 utilized both generated e− and h+ for degradation of atrazine. Thus, the photocatalytic atrazine degradation by the synthesized Cu-ZnO/g-C3N4 was greater than those of single g-C3N4 or Cu-ZnO materials. Finally, the conducted recycling experiments indicated great stability of synthesized Cu-ZnO/g-C3N4 during long-term atrazine degradation process opening new era for application of the material in practical systems.
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•Cu doped into ZnO lattice to reduce its band gap and to extend its visible radiation response.•Cu-ZnO was successfully combined with g-C3N4 to establish Z direct scheme system.•Z-scheme prevented fast recombination of e− and h+ and maintained their re-dox potential.•The Cu-ZnO/g-C3N4 utilized both generated e− and h+ for degradation of atrazine.•The Cu-ZnO/g-C3N4 showed excellent activity and stability during long-term photocatalysis.
In the study, we successfully decorated MnFe2O4 on BiVO4 to highly improve its photocatalytic activity for degradation of tetracycline as well as its magnetically recovery. The decoration of MnFe2O4 ...on BiVO4 led to formation of MnFe2O4/BiVO4 Z scheme heterojunction to effectively prevent the charge recombination in each material. Upon visible light, the MnFe2O4/BiVO4 heterojunction produced significant available amounts of e− and h+ existing in the conduction band of the MnFe2O4 and the valence band of the BiVO4, respectively. These produced e− on the conduction band of the MnFe2O4, which reduction potential was approximately −0.41 eV, exhibited strong reduction potential reducing oxygen to produce •O2− radicals while h+ on the valence band of the BiVO4, which oxidation potential was 2.77 eV, showed strong oxidation potential oxidizing water and hydroxyl groups to produce •OH radicals. These generated active oxygen radicals effectively degraded TC in water (~92%). The used photocatalysts were easily recovered from photocatalytic suspension using an external magnet due to high magnetically activity of the MnFe2O4, which tightly bonded with BiVO4 in the MnFe2O4/BiVO4 heterojunction. Finally, the recovered MnFe2O4/BiVO4 heterojunction was very active and stable for tetracycline degradation in long-term process.
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•Ag–TiO2/GF exhibits high disinfection activity even under visible light.•The disinfection efficiency depends on the Ag content in Ag–TiO2/GF.•The intermediate humidity was the ...optimum condition for the disinfection.•The highest disinfection capacity by 7.5% Ag–TiO2/GF was 26CFU/scm2.
Ag doped TiO2/glass fibers (Ag–TiO2/GF) were prepared and used for photocatalytic disinfection of Escherichia coli (E. coli) in an indoor air environment. The prepared photocatalysts were characterized using scanning electron microscope (SEM) for morphology, X-ray diffraction (XRD) for microstructure, UV–Visible diffuse reflectance spectra (DRS) for optical properties and X-ray photoelectron spectroscopy (XPS) to determine elemental state. The optimized weight fraction of TiO2 in the TiO2/glass fiber (TiO2/GF) was 3%. The silver content in Ag/TiO2 was altered from 1% to 10% to investigate the optimal ratio of Ag doped on the TiO2/GF for the photocatalytic disinfection of E. coli. Doped Ag enhanced the electron–hole separation as well as charge transfer efficiency between the valance band and the conduction band of TiO2. The generated electron–hole pairs reacted with water and molecular oxygen to form strong oxidative radicals, which participated in the oxidation of organic components of E. coli, resulting in bacterial death. The photocatalytic disinfection activity under visible light increased with the increase in silver content up to 7.5% and then decreased slightly with further increasing Ag content. Among the three humidity conditions used in this study (40±5%, 60±5%, 80±5%), the highest disinfection ratio of E. coli by the photocatalytic system was observed in the intermediate humidity level followed by the high humidity level. Using the 7.5% Ag–TiO2/GF and the intermediate level of humidity (60±5%), the highest disinfection ratio and disinfection capacity of E. coli were 93.53% and 26 (CFU/scm2), respectively.
Herein, g-C3N4 and NiMoO4, which are moderate energy band gap semiconductors, have been effectively hybridized to create Z scheme heterojunction for successful visible-light photocatalytic converting ...CO2 into valuable products including CH4, CO, O2 and HCOOH. Ni(NO3)2·6H2O and (NH4)6Mo7O24·4H2O were used as precursors to synthesize NiMoO4 photocatalyst, which was continuously mixed with melamine before calcinating at 520 °C for 6 h to get NiMoO4/g-C3N4 Z scheme heterojunction. We explored that NiMoO4 intimately contacted with g-C3N4. These band positions of the NiMoO4 were also perfectly matched with those of the g-C3N4. Therefore, these photo-induced e− on conduction band of the NiMoO4 could easily travel to h+ on valence band of the g-C3N4 (recombination); thereby, minimize h+ and e− recombination in each material. Therefore, the NiMoO4/g-C3N4 direct Z-scheme heterojunctions could produce significant available h+ on the valence band of the NiMoO4 and e− on the conduction band of the g-C3N4. These e−/h+ have suitable redox potential to effectively convert CO2. Finally, the optimized g-C3N4 mole ratio for maximum enhancing photocatalytic efficiency of the NiMoO4/g-C3N4 heterojunction was 60%. When the g-C3N4 content increased to 70%, the excess g-C3N4 amount would entirely cover NiMoO4 surface leaded to form dense and closed shell. The formed closed shell decreased contact between NiMoO4 and CO2 as well as the interface charge transfer, which reduced the e− and h+ separation and transfer leading to decrease in photocatalytic conversion efficiency.
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•Successfully created NiMoO4/g-C3N4 Z scheme heterojunction for CO2 conversion.•Hybridization of NiMoO4 and g-C3N4 prevented recombination of e−/h+ in each material.•The created NiMoO4/g-C3N4 converted CO2 into HCOOH, CH4 and CO even under visible light.•The optimal molar ratio of g-C3N4/NiMoO4 for the best photocatalytic conversion was 60%.
