Preparation and characterization of visible-light-active nitrogen-doped TiO_2 photocatalyst

A visible-light photocatalyst was prepared by calcination of the hydrolysis product of Ti(SO_4)_2 with ammonia as precipitator. The color of this photocatalyst was vivid yellow. It could absorb light under 550 nm wavelength. The crystal structure of anatase was characterized by XRD. The structure analysis result of X-ray fluorescence(XRF) shows that doped-nitrogen was presented in the sample. The photocatalytic activities were evaluated using methyl orange and phenol as model pollutants. The photocatalytic activities of samples were increasing gradually with calcination temperature from 400℃ to 700℃ under UV irradiation. It can be seen that the degradation of methyl orange follows zero-order kinetics. However, the calcination temperatures have no significant influence on the degradation of phenol under sunlight. The N-doped catalyst shows higher activity than the bare one under solar irradiation.

First-principles study of the electronic and optical properties of the (Y,N)-codoped anatase TiO_2 photocatalyst

First-principles plane-wave pseudopotential calculations are performed to study the geometrical structures, for- mation energies, and electronic and optical properties of Y-doped, N-doped, and （Y, N）-codoped Ti02. The calculated results show that Y and N codoping leads to lattice distortion, easier separation of photogenerated electron-hole pairs and band gap narrowing. The optical absorption spectra indicate that an obvious red-shift occurs upon Y and N codoping, which enhances visible-light photocatalytic activity.

Spectra analysis and O_2 evolution for TiO_2 photocatalyst compounded with indirect transition semiconductors

The photo absorbing, photo transmitting and photoluminescence performances of WiO2 photocatalysts compounded with V2O5 or WO3 were investigated by UV-Vis spectra, transmitting spectra, and PL spectra, respectively. The energy band structures of TiO2 photocatalysts were analyzed. The photocatalytic activities of the TiO2 photocatalysts were investigated by splitting of water for 02 evolution. The results indicate that the band gaps of WO3 and V205 are about 2.8 and 2.14 eV, respectively, and the band gap of rutile TiO2 is about 3.08 eV. Speeds of water splitting for 2%WO3-TiO2 and 8%V2O5-TiO2 photocatalysts are 420 and 110 μmol/（L.h）, respectively, under UV light irradiation. V2O5 and WO3 compounded with suitable concentration can improve the photocatalytic activity of TiO2 with Fe3＋ as electron acceptor.

Degradation of phenol in industrial wastewater over the F–Fe/TiO_2 photocatalysts under visible light illumination

F–Fe/TiO_2 composite photocatalyst was synthesized by a facile one-step hydrothermal method and then characterized by XRD, XPS and UV–Vis DRS. The catalyst of F–Fe/TiO_2 exhibited the highest photodegradation rate for phenol as compared with pure TiO_2, F/TiO_2, Fe/TiO_2, F0.38–Fe0.13–TiO_2 and Fe(III)/F-TiO_2 under visible light irradiation. The simulated conditions of industrial phenolic wastewater including initial phenol concentration,visible light intensity, p H and different anions were investigated in the presence of F–Fe/TiO_2 photocatalyst. In addition, as expected, the F–Fe/TiO_2 photocatalyst displayed excellent stability, showing a potential industrial application for the treatment of phenolic wastewater.

Photocatalytic degradation kinetics in Rhodamine B dye degradation with poriferous TiO_2 photocatalyst

A type of poriferous TiO2 material was prepared using cetyl trimethyl ammonium bromide as a template agent and butyl tetra titanate as a precursor. Through studying the photocatalytic kinetic activity of Rhodamine B photocatalytic degradation reaction with a UV-1601PC ultraviolet-visible spectrophotometer, the photocatalytic degradation process of Rhodamine B was found to not correspond to the first-order kinetic process completely. According to the reaction phenomenon, the photocatalytic degradation process of Rhodamine B with poriferous TiO2 involved two irreversible reactions. The kinetic model was tested using experimental data.

Fe/C Modified TiO_2 Photocatalyst and Photodegradation of 4-t-octylphenol

[Objective]The research aimed to study synthesis of the TiO2 photocatalyst modified by Fe/C and photodegradation of 4-t-octylphenol.[Method]Fe/C modified TiO2 photocatalyst was made by sol-gel and solvothermal synthesis methods.4-t-octylphenol as test object,photocatalytic performance of the catalyst was investigated.Influences of the Fe doping amount,catalyst amount,pH and sun-light irradiation on reaction were discussed.Moreover,catalyst performance under the condition of interfering ion existence was studied.[Result]When Fe/C doping amount was 0.6%,under the reaction condition of 25 ℃,pH =9.0,300 W mercury lamp and 1.0 g/L of catalyst amount,4-t-octylphenol concentration decreased from 1.00 to 0.02 mg/L by degradation for 100 min.Rises of pH and light intensity could improve catalyst efficiency.The existences of Na ＋,K ＋ and Ca2＋ had no effect on degradation activity of the catalyst.[Conclusion]Fe/C modified TiO2 photocatalyst had better degradation effect on environmental hormone in the sewage.

Cu/TiO_(2) Photocatalysts for CO_(2) Reduction: Structure and Evolution of the Cocatalyst Active Form

Extensive work on a Cu-modified TiO_(2) photocatalyst for CO_(2) reduction under visible light irradiation was conducted. The structure of the copper cocatalyst was established using UV-vis diff use refl ectance spectroscopy, high-resolution transmis- sion electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. It was found that copper exists in different states (Cu 0 , Cu^(+) , and Cu^(2+) ), the content of which depends on the TiO_(2) calcination temperature and copper loading. The optimum composition of the cocatalyst has a photocatalyst based on TiO_(2) calcined at 700℃ and modified with 5 wt% copper, the activity of which is 22 μmol/(h·g cat ) (409 nm). Analysis of the photocatalysts after the photocatalytic reaction disclosed that the copper metal on the surface of the calcined TiO_(2) was gradually converted into Cu_(2) O during the photocatalytic reaction. Meanwhile, the metallic copper on the surface of the noncalcined TiO_(2) did not undergo any trans- formation during the reaction.

N-doped graphene quantum dot-decorated N-TiO2/P-doped porous hollow g-C_(3)N_(4) nanotube composite photocatalysts for antibiotic photodegradation and H2 production

Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.

Co_(3)O_(4)/TiO_(2) composite photocatalyst:Preparation and synergistic degradation performance of toluene

TiO_(2) nanobelts and Co_(3)O_(4)/TiO_(2) catalytic materials were prepared using the hydrothermal method.The cat-alyst was characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,X-ray electron spectroscopy,and fluorescence spectroscopy.At room temperature,with a relative humidity of 50.0%,the total gas flow rate of 1.0 L·min-1,the space velocity of 1.05×10^(4) h^(-1),and toluene volume concentration of 25.0µL·L^(-1),two 6 W vacuum ultraviolet lamps were used as light sources to catalyze,degrade,and mineralize toluene.The results show that the prepared catalyst is in the shape of nano-ribbons.The loading of Co_(3)O_(4) inhibits the recombina-tion of photogenerated electrons and holes and can effectively improve the catalytic performance.The Co_(3)O_(4)/TiO_(2) with a load of 6.0%Co_(3)O_(4) has the best catalytic effect.When N2 was used as a carrier gas,the degradation rate of tol-uene was only 34.7%.The toluene degradation is mainly due to the photolysis of vacuum ultraviolet light.When air was used as a carrier gas,O_(3) was produced.The Co_(3)O_(4)/TiO_(2) with a load of 6.0%and vacuum ultraviolet synergistical-ly promote toluene degradation.The highest degradation rate of toluene was 91.7%and the mineralization rate was 74.6%.The degradation rate of toluene was 2.6 times that of nitrogen as a carrier gas.

TiO2-PES Fibrous Composite Material for Ammonia Removal Using UV-A Photocatalyst

This study focused on the development and characterization of TiO2-PES composite fibers with varying TiO2 loading amounts using a phase inversion process. The resulting composite fibers exhibited a sponge-like structure with embedded TiO2 nanoparticles within a polymer matrix. Their photocatalytic performance for ammonia removal from aqueous solutions under UV-A light exposure was thoroughly investigated. The findings revealed that PeTi8 composite fibers displayed superior adsorption capacity compared to other samples. Moreover, the study explored the impact of pH, light intensity, and catalyst dosage on the photocatalytic degradation of ammonia. Adsorption equilibrium isotherms closely followed the Langmuir model, with the results indicating a correlation between qm values of 2.49 mg/g and the porous structure of the adsorbents. The research underscored the efficacy of TiO2 composite fibers in the photocatalytic removal of aqueous under UV-A light. Notably, increasing the distance between the photocatalyst and the light source resulted in de-creased hydroxyl radical concentration, influencing photocatalytic efficiency. These findings contribute to our understanding of TiO2 composite fibers as promising photocatalysts for ammonia removal in water treatment applications.

Ag/TiO_2/freeze-dried graphene nanocomposite as a high performance photocatalyst under visible light irradiation

Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.

A review on TiO_2-based Z-scheme photocatalysts

TiO2‐based Z‐scheme photocatalysts have attracted considerable attention because of the low recombination rate of their photogenerated electron–hole pairs and their high photocatalytic efficiency.In this review,the reaction mechanism of Z‐scheme photocatalysts,recent research progress in the application of TiO2‐based Z‐scheme photocatalysts,and improved methods for photocatalytic performance enhancement are explored.Their applications,including water splitting,CO2reduction,decomposition of volatile organic compounds,and degradation of organic pollutants,are also described.The main factors affecting the photocatalytic performance of TiO2‐based Z‐scheme photocatalysts,such as pH,conductive medium,cocatalyst,architecture,and mass ratio,are discussed.Concluding remarks are presented,and some suggestions for the future development of TiO2‐based Z‐scheme photocatalysts are highlighted.

Visible light responsive N-F-codoped TiO_2 photocatalysts for the degradation of 4-chlorophenol

N-F-codoped TiO2 （NFTO） photocatalysts were synthesized by a simple sol-gel process with tetrabutyl titanate （Ti（OBu）4 ） as the precursor of TiO 2 and ammonium fluoride （NH4 F） as the source of N and F.The synthesized photocatalysts were investigated by X- ray diffraction （XRD）,X-ray photoelectron spectroscopy （XPS）,ultraviolet-visible diffuse reflectance spectroscopy （UV-Vis DRS） and photodegradation reaction tests of 4-chlorophenol under visible light irradiation to understand the relationship between the structure of NFTO catalyst and corresponding photocatalytic activity.The crystal phase and particle size of catalysts were found to be largely affected by the calcination temperature.In addition,N-F-codoping could inhibit phase transition of TiO2 from anatase to rutile.The presence of N and F atoms in the lattice of TiO2 is responsible for the visible light catalytic activity.In UV-Vis DRS tests,the spectrum of NFTO exhibited red shift compared with Degussa P25 and the band gap was reduced to around 2.92 eV.Under optimal calcination temperature and dopant concentration conditions,the NFTO photocatalyst exhibited the highest activity in the photodegradation reaction tests of 4-chlorophenol under visible light irradiation with a degradation rate of 75.84%.Besides,the 5-recycle test showed that NFTO photocatalyst could be reused and its activity kept stable under visible light irradiation.

TiO_2/polyaniline composites:An efficient photocatalyst for the degradation of methylene blue under natural light

Polyaniline （PAn） sensitized nanocrystalline TiO2 composites （TiO2/PAn） were successfully prepared and used as an efficient photocatalyst for the degradation of dye methylene blue （MB）. The results showed that PAn was able to sensitize TiO2 efficiently and the composite photocatalyst could be activated by absorbing both the ultraviolet and visible light （λ： 190 ～ 800 nm）, whereas pure TiO2 absorbed ultraviolet light only （λ 〈 380 nm）. Under the irradiation of natural light, MB could be degraded more efficiently on the TiO2/PAn composites than on the TiO2 Furthermore, it could be easily separated from the solution by simple sedimentation.

Photocatalytic remediation ofγ-hexachlorocyclohexane contaminated soils using TiO_2 and montmorillonite composite photocatalyst

TiO2 and montmorillonite composite photocatalysts were prepared and applied in degrading γ-hexachlorocyclohexane （γ-HCH） in soils. After being spiked with γ-HCH, soil samples loaded with the composite photocatalysts were exposed to UV-light irradiation. The results indicated that the photocatalytic activities of the composite photocatalysts varied with the content of TiO2 in the order of 10%〈70%〈50% 〈30%, Moreover, the photocatalytic activity of the composite photocatalysts with TiO2 content 30% was higher than that of the pure P25 with the same mass of TiO2. The strong adsorption capacity of the composite photocatalysts and quantum size effect may contribute to its increased photocatalytic activities. In addition, effect of dosage of composite photocatalysts and soil pH on γ-HCH photodegradation was investigated. Pentachlorocyclohexene, trichlorocyclohexene, and dichlorobenzene were detected as photodegradation intermediates, which were gradually degraded with the photodegradation evolution.

TiO_2 thin film photocatalyst

It is well known that the photocatalytic activity of TiO_2 thin filmsstrongly depends on the preparing methods and post-treatment conditions, since they have a decisiveinfluence on the chemical and physical properties of TiO_2 thin films. Therefore, it is necessary toelucidate the influence of the preparation process and post-treatment conditions on thephoto-catalytic activity and surface microstructures of the films. This review deals with thepreparation of TiO_2 thin film photo-catalysts by wet-chemical methods (such as sol-gel,-reversemicellar and liquid phase deposition) and the comparison of various preparation methods as well astheir advantage and disadvantage. Furthermore, it is discussed that the advancement ofphotocatalytic activity, super-hydrophilicity and bactericidal activity of TiO_2 thin filmphotocatalyst in recent years.

(N,F)-codoped TiO_2 Nanocrystals as Visible Light-activated Photocatalyst

（N, F）-codoped anatase TiO2 nanocrystals with active visible light response were prepared by using a simple sol-gel approach. X-ray photoelectron spectroscopy measurements suggested that the substitutional N and F species replaced the lattice oxygen atoms in TiO2 nanocrystals. Such nanocrystals showed strong absorption from 400 to 550 nm, which was mainly induced by nitrogen doping. The phase transformation from anatase to rutile was hindered by fluorine doping at high calcination temperatures, which was verified by XRD patterns. The N2 adsorption-desorption isotherms revealed the absence of mesopores in these nanocrystals. The （N, F）- codoped TiO2 nanocrystals showed satisfying photocatalytic activity on the photo-degradation of methylene blue under visible light.

A Novel High Active TiO_2/AC Composite Photocatalyst Prepared by Acid Catalyzed Hydrothermal Method

A high active novel TiO2/AC composite photocatalyst was prepared and used for phenol degradation. It was much more active than P-25 and exhibiting good decantability, less deactivation after several runs and less sensitive to pH change. Diffuse reflectance spectra （DRS） revealed that the electronic change in TiO2 did not occur by the addition of AC. Results of SEM and XRD suggested that better TiO2 distribution can be achieved when optimal AC content was adopted. The performance of the prepared TiO2/5AC catalyst revealed great practical potential in wastewater treatment field.

Bioinspired C/TiO_2 photocatalyst for rhodamine B degradation under visible light irradiation

Papilio paris butterfly wings were replicated by a sol-gel method and a calcination process, which could take advantage of the spatial features of the wing to enhance their photocatalytic properties. Hierarchical structures of P. paris-carbon-TiO_2(PP-C-TiO_2) were confirmed by SEM observations. By applying the Brunauer-Emmett-Teller method, it was concluded that in the presence of wings the product shows higher surface area with respect to the pure TiO_2 made in the absence of the wings. The higher specific surface area is also beneficial for the improvement of photocatalytic property.Furthermore, the conduction and valence bands of the PPC-TiO_2 are more negative than the corresponding bands of pure TiO_2, allowing the electrons to migrate from the valence band to the conduction band upon absorbing visible light. That is, the presence of C originating from wings in the PP-C-TiO_2 could extend the photoresponsiveness to visible light. This strategy provides a simple method to fabricate a high-performance photocatalyst,which enables the simultaneous control of the morphology and carbon element doping.

Study on anti-fungal activity of nitrogen-doped TiO_2 nanophotocatalyst under visible light irradiation

Nitrogen-doped TiO_2 nanophotocatalysts were prepared,and characterized by XRD patterns and UV-vis spectroscopy.The results indicated that nitrogen was doped effectively and the shift of the absorption edge to a lower energy and a stronger absorption in the visible light region were observed.The calcinations temperature is a key factor to narrow the band gap of titania,and consequently affects the response to visible light of nitrogen-doped TiO_2 nanocrystals.This photocatalyst can effectively inhibit the g...