As efficient water treatment agents, a novel series of rectorite-based ZnO and TiO2 hybrid composites（REC/ZnO/TiO2） were synthesized and characterized in this study. Effects of experimental parameters including TiO2...As efficient water treatment agents, a novel series of rectorite-based ZnO and TiO2 hybrid composites（REC/ZnO/TiO2） were synthesized and characterized in this study. Effects of experimental parameters including TiO2 mass ratio, solution p H and catalyst dosage on the removal of methyl blue（MB） were also conducted. The presence of a little mass ratio（2%-6%） of TiO2 highly promoted the photoactivity of REC/ZnO/TiO2 in removal of MB dye from aqueous solution, in which ZnO and REC played a role of photocatalyst and adsorbent. The promotion effects of TiO2 may result from the accelerated separation of electron-hole on ZnO. The observed kinetic constant for the degradation of MB over REC/ZnO and REC/ZnO/TiO2 were 0.015 and 0.038 min^（-1）, respectively. The degradation kinetics of MB dye, which followed the Langmuir–Hinshelwood model, had a reaction constant of 0.17 mg/（L min）. The decrease of removal ratio of MB after five repetitive experiments was small, indicating REC/ZnO/TiO2 has great potential as an effective and stable catalyst.展开更多
In this work, we have shown that mining waste derived Fe^3＋can be used to enhance the photocatalytic activity of TiO2. This will allow us to harness a waste product from the mines, and utilize it to enhance TiO2 phot...In this work, we have shown that mining waste derived Fe^3＋can be used to enhance the photocatalytic activity of TiO2. This will allow us to harness a waste product from the mines, and utilize it to enhance TiO2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO2 and biogenic jarosite. Evidence of Fe／O／Ti bonding in the TiO2/jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO2, biogenic jarosite and mechanically mixed sample of jarosite and TiO2 under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO2 nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO2 and jarosite derived Fe^3＋as was shown from the EELS and ELNEFS. Generation of OHU was supported by photoluminesence（PL） experiments.展开更多
Highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti foil in fluoride-containing electrolyte. The effects of applied anodization potential, anodization time on the form...Highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti foil in fluoride-containing electrolyte. The effects of applied anodization potential, anodization time on the formation of TiO2 nanotube arrays and the photocatalytic degradation of methylene blue （MB） were discussed. The TiO2 nanotube arrays calcined at 500 ℃ for 2 h show pure anatase phase. The pore diameters of TiO2 nanotube arrays can be adjusted from 30 to 90 nm using a different anodization voltage. Anodization time mainly influenced TiO2 tube length, and by increasing the anodization time, the nanotube length became longer gradually. When the anodization potential was 40 V, the average growth rate of TiO2 nanotube was about 4.17 μm/h. Both anodization potential and time had important effects on the photocatalytic efficiency. The TiO2 nanotube arrays obtained at anodization potential of 40 V for I h showed the best photocatalytic degradation ratio of MB.展开更多
Mesoporous anatase TiO2 spheres with high surface area（119 m^2g^（-1）） were successfully synthesized via a facile and green template-free method. The prepared TiO2 was characterized by X-ray diffraction（XRD）,N2 a...Mesoporous anatase TiO2 spheres with high surface area（119 m^2g^（-1）） were successfully synthesized via a facile and green template-free method. The prepared TiO2 was characterized by X-ray diffraction（XRD）,N2 adsorption, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and UV–vis absorbance spectra. It was found that the prepared TiO2 is characterized by pure anatase phase, which shows uniform spheres and has a typical mesostructure with a high specific surface area and a large pore volume. The effects of complexant（acetylacetone） amount, crystallization temperature and calcination temperature were also investigated. Based on the results, a sketch for the preparation of mesoporous TiO2 was proposed. First, complex formed between tetrabutyl titanate and acetylacetone in ethanol. After introduction of aqueous of ammonia sulfate and urea, hydrolysis of tetrabutyl titanate would occur slowly,and sol of TiO2 was formed. Then, crystallization proceeded under hydrothermal conditions. Calcination process favored the formation of bigger TiO2 crystal through combining of the small crystals in TiO2.This led to the formation of bigger mesopores between TiO2 crystals. Photocatalytic activity of the prepared TiO2 was evaluated by decomposition of methyl orange.展开更多
TiO2/EDTA-rich carbon composites （TiO2/EDTA-RC） have been successfully synthesized via a low temperature carbonization process. TiO2/EDTA-RC exhibits marked absorption of visible light and excellent photoreduction o...TiO2/EDTA-rich carbon composites （TiO2/EDTA-RC） have been successfully synthesized via a low temperature carbonization process. TiO2/EDTA-RC exhibits marked absorption of visible light and excellent photoreduction of Cr（Ⅵ） activity under visible light irradiation （λ 〉 420 nm）. Due to the high carboxyl group content and strong coordination ability of EDTA, TiO2-EDTA complex can be easily fabricated between EDTA incorporated in carbon sheet and titanol group on the surface of TiO2. TiO2- EDTA complexes on the surface of TiO2/EDTA-RC, the LMCT complex, are responsible for the prominent photoreduction of Cr（Ⅵ） properties of TiO2/EDTA-RC under visible light irradiation. In addition, the unique structure of TiO2/EDTA-RC is also propitious to the visible-light photocatalytic reduction of Cr（Ⅵ）. Carbon sheet of TiO2/EDTA-RC acts as a supporter. Tio2 nanoparticles and EDTA homogeneously disperse into the carbon sheet supporter and form the TiO2-EDTA complexes, which can avoid the aggregation of TiO2 nanoparticles in the aqueous solution and provide more photocatalytic reaction points for the reduction of Cr（Ⅵ）.展开更多
Pt-TiO2 nanotubes with tube diameter of -120 nm and uniformly dispersed Pt particles（size of -2 nm） were successfully synthesized via a carbon nanotube（CNT） templating method followed by a photo-deposition process...Pt-TiO2 nanotubes with tube diameter of -120 nm and uniformly dispersed Pt particles（size of -2 nm） were successfully synthesized via a carbon nanotube（CNT） templating method followed by a photo-deposition processing of Pt nanoparticles. The as-obtained Pt-TiO2 NTs possess both enhanced visible light absorption and reduced recombination of photogenerated electrons and holes. These merits boost the Pt-TiO2 NTs an excellent photocatalytic material toward photooxidation of a variety of low molecular hydrocarbons under atmospheric environment.展开更多
As a decorative material, magnesium oxychloride cement was used as a photocatalyst supporter to purify the pollutants indoors. Due to excellent adsorption properties of activated carbon（AC）, the photocatalytic compo...As a decorative material, magnesium oxychloride cement was used as a photocatalyst supporter to purify the pollutants indoors. Due to excellent adsorption properties of activated carbon（AC）, the photocatalytic composties, TiO2/AC, were prepared and introduced into the porous magnesium oxychloride cement（PMOC） substrate to composite a sort of photocatalytic cementitious material（PCM）. The optimal composite processes were assessed by gas chromatograph, using toluene as the target. By comparing the perspective of toluene purification and thorough decomposition, it can be found that the optimal mass ratio for TiO2/AC composites is 4/25, and the heat treatment to TiO2/AC sample at 350 ℃ can play the optimal synergetic role of adsorbents in photocatalytic process. The synergistic effect of TiO2, AC and magnesium oxychloride cement（MOC） was also evaluated by gas chromatograph. One-take molding process was adopted to introduce the TiO2/AC into PMOC substrate, and its optimal mass fraction was 4 wt%, while the appropriate density of substrate was 0.35 g/cm3. Toluene degradation showed that the prepared PCM can degrade pollutants efficiently. The appropriate treatment process of TiO2/AC, mass of TiO2/AC, substrate density, and stable pore structure should be coordinated to maximize the adsorption-photodegradation performance. The combination of photocatalytic materials, adsorbents, and building materials provided a new idea for the application of photocatalysis.展开更多
In this article, the effects of ZiO2 surface fluorination and sulfation, on the active oxygen species formed at the reduction site in the photocatalytic process, namely O2^＊- and H2O2, were investigated from a new pe...In this article, the effects of ZiO2 surface fluorination and sulfation, on the active oxygen species formed at the reduction site in the photocatalytic process, namely O2^＊- and H2O2, were investigated from a new perspective. The superoxide radical, （O2^＊-）, was determined by colorimetry of nitroblue tetrazolium, a prominent O2^＊- scavenger. Hydrogen peroxide （H2O2） was estimated by using the iodide-starch method. In the naked TiO2 photocatalysis, O2^＊-, though less reactive, was a very important intermediate. When the TiO2 surface was fluorinated, more O2^＊- and H2O2 were produced, which indicated that the surface modification could greatly reduce the recombination of photogenerated electrons and holes, thus enhancing the photocatalytic rate. In the sulfated system, photocatalysis proceeded with a more complicated mechanism. These results added support to the view of fluoride-induced enhancement and sulfide＇s nonappreciable inhibition effect.展开更多
Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight ...Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight reactors.In the paper,experiments were carried out to remove formaldehyde(HCHO),ammonia(NH_3) and volatile organic compounds(VOCs)in the airtight and ventilated chambers.Results demonstrated that 90.4%of HCHO,92.3%of NH_3 and 57.9%of VOCs were removed in the amine adsorption process,while 67.5% (hereinbefore,these are the mass fraction)of HCHO,60.0%of NH_3,and 61.2%of VOCs were removed in the photocatalytic process.However,ozone-assisted photocatalytic process showed great potential to degrade indoor air pollutants in the ventilated chamber.Factors and mechanisms of the photocatalytic degradation of HCHO, NH_3 and VOCs were also discussed.展开更多
A nitrogen-doped titanium dioxide composite photocatalyst（N–TiO2） with heterojunction structures is synthesized by three different approaches： a novel UV-assisted thermal synthesis, annealing, and microwave techni...A nitrogen-doped titanium dioxide composite photocatalyst（N–TiO2） with heterojunction structures is synthesized by three different approaches： a novel UV-assisted thermal synthesis, annealing, and microwave technique. Photocatalytic activities of synthesized photocatalysts are evaluated by the degradation of Methyl Orange under ultraviolet light types A（UV-A）, B（UV-B）, and C（UV-C）, visible light, and direct sunlight irradiation. Results show that by using N–TiO_2 photocatalyst prepared by the UV-assisted thermal synthesis and annealing, the degradation increases by 16.5% and 20.4%, respectively, compared to that by bare TiO2. The best results are obtained at a nitrogen to TiO2 mass ratio of 0.15（N：TiO2）. The enhancement of the photocatalytic activity observed in the visible range is mainly attributed to the increasing separation rate of photogenerated charge carriers. The novel UV-assisted thermal synthesis has produced encouraging results as a preparation method for the nitrogen-doped TiO2 photocatalyst; thus, further studies are recommended for process optimization, immobilization, and scale-up to evaluate its applicability in wastewater treatment.展开更多
The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission elect...The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.展开更多
It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. ...It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline Ti O2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3.The obtained samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline Ti O2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline Ti O2,due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline Ti O2 prepared at R HNO3= 0.8, containing80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity,about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline Ti O2 will enrich the chemistry of the Ti O2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic.展开更多
Photocatalysis has attracted worldwide attention due to its potential in solar energy conversion.As a ＂green＂ advanced oxidation technology, it has been extensively used for water disinfection and wastewater treatme...Photocatalysis has attracted worldwide attention due to its potential in solar energy conversion.As a ＂green＂ advanced oxidation technology, it has been extensively used for water disinfection and wastewater treatment. This article provides a review of the recent progress in solar energy-induced photocatalytic disinfection of bacteria, focusing on the development of highly efficient photocatalysts and their underlying mechanisms in bacterial inactivation. The photocatalysts are classified into Ti O2-based and non-Ti O2-based systems, as Ti O2 is the most investigated photocatalyst. The synthesis methods, modification strategies, bacterial disinfection activities and mechanisms of different types of photocatalysts are reviewed in detail.Emphasis is given to the modified Ti O2, including noble metal deposition, non-metal doping,dye sensitization and composite Ti O2, along with typical non-Ti O2-based photocatalysts for bacterial disinfection, including metal oxides, sulfides, bismuth metallates, graphene-based photocatalysts, carbon nitride-based photocatalysts and natural photocatalysts. A simple and versatile methodology by using a partition system combined with scavenging study is introduced to study the photocatalytic disinfection mechanisms in different photocatalytic systems. This review summarizes the current state of the work on photocatalytic disinfection of bacteria, and is expected to offer useful insights for the future development in the field.展开更多
A series of graphene–TiO2photocatalysts was synthesized by doping TiO2 with graphene oxide via hydrothermal treatment. The photocatalytic capability of the catalysts under ultraviolet irradiation was evaluated in ter...A series of graphene–TiO2photocatalysts was synthesized by doping TiO2 with graphene oxide via hydrothermal treatment. The photocatalytic capability of the catalysts under ultraviolet irradiation was evaluated in terms of sodium pentachlorophenol（PCP-Na） decomposition and mineralization. The structural and physicochemical properties of these nanocomposites were characterized by X-ray diffraction, N2adsorption–desorption, transmission electron microscopy, scanning electron microscopy, Ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectra, and Fourier-transform infrared spectroscopy. The graphene–TiO2nanocomposites exhibited higher photocatalytic efficiency than commercial P25 for the degradation of PCP-Na, and 63.4% to 82.9% of the total organic carbon was fully mineralized. The improved photocatalytic activity may be attributed to the accelerated interfacial electron-transfer process and the significantly prolonged lifetime of electron-hole pairs imparted by graphene sheets in the nanocomposites. However,excessive graphene and the inhomogeneous aggregation of TiO2 nanoparticles may decrease photodegradation efficiency.展开更多
Carbon-modified titanium dioxide （TiO2） was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation （PCO） of gaseo...Carbon-modified titanium dioxide （TiO2） was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation （PCO） of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range （〈 300℃）. However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.展开更多
A double-layer TiO2 nanotube arrays were formed by two-step anodization of Ti foils in different electrolytes. First, Ti in 0.5 wt% HF was anodized to form thin nanotube layer. Afterwards a second anodization was cond...A double-layer TiO2 nanotube arrays were formed by two-step anodization of Ti foils in different electrolytes. First, Ti in 0.5 wt% HF was anodized to form thin nanotube layer. Afterwards a second anodization was conducted in a formamide based electrolyte, which allowed the second layer of nanotube growing directly underneath the first one. From FESEM investigation we found that the thickness of second layer corresponded to the anodization time, the increasing of which would lead to the excessive etching on the first layer. The first layer protected the lower one from fluoride corrosion during anodization process. The double layer TiO2 nanotube arrays showed no benefit to photodegradation effect in methyl orange degradation experiments.展开更多
TiO2 nanotubes（TNTs） with nickel sulfide（NiS） co-catalyst were prepared by a simple solvothermal method and characterized by X-ray diffraction, transmission electron microscope, N2-physisorption, UV–vis diffuse r...TiO2 nanotubes（TNTs） with nickel sulfide（NiS） co-catalyst were prepared by a simple solvothermal method and characterized by X-ray diffraction, transmission electron microscope, N2-physisorption, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. Loading NiS nano-clusters can significantly enhance the photocatalytic H2 evolution performance of TNTs. The optimum NiS loading content was found to be 8 wt% and the corresponding hydrogen production rate is ca. 7486 μmol/h/g, being about 79 times higher than that of pure TNTs. This enhancement of photocatalytic H2 evolution was attributed to the synergistic effect between NiS and TNTs.展开更多
Bothβ-andγ-hydroxyketone structures are important units in biologically active molecules,synthetic drugs and fine chemicals.Although there are some routes available for their manufacture from pre-functionalized grou...Bothβ-andγ-hydroxyketone structures are important units in biologically active molecules,synthetic drugs and fine chemicals.Although there are some routes available for their manufacture from pre-functionalized groups on one or two matrix molecule(s),the approaches to simply and simultaneously deposit two oxygen atoms from dioxygen into two specific C(sp^(3))positions of pure saturated hydrocarbons have rarely succeeded because they are involved in the targeted activation of three inert C–Hσbonds all at once.Here,we show that a TiO_(2)-CH_(3)CN photocatalytic suspension system enables the insertion of dioxygen into one C(sp^(3))–C(sp^(3))bond of strained cycloparaffin derivatives,by which difunctionalized hydroxyketone products are obtained in a one-pot reaction.With the cleavage event to release strain as the directional driving force,as-designed photocatalytic reaction systems show 21 examples ofβ-hydroxyketone products with 31%–76%isolated yields for three-membered ring derivatives and 5 examples ofγ-hydroxyketone products with 30%–63%isolated yields for four-membered ring substrates.^(18)O isotopic labeling experiments using^(18)O2,Ti^(18)O_(2) and intentionally added H218O,respectively,indicated that both oxygen atoms of hydroxyketone products were exclusively from dioxygen,suggesting a previously unknown H^(+)/TiO_(2)-e−catalyzed arrangement pathway of the hydroperoxide intermediate to convert dioxygen into hydroxyketone units.展开更多
Photocatalysis has been regarded as one of best solutions to using the sunlight to produce hydrogen from water and to removing organic pollutants from the environment, and titanium dioxide （TiO2） nanomate- rials hav...Photocatalysis has been regarded as one of best solutions to using the sunlight to produce hydrogen from water and to removing organic pollutants from the environment, and titanium dioxide （TiO2） nanomate- rials have been treated as the primary photocatalyst for these purposes. However. their large band gap has largely limited the activity to the UV region of the solar spectrum. The discovery of black TiO2 in 2011 has triggered world-wide research interests with new hope to overcome this problem. This review briefly summarizes the recent progresses of black TiO2 nanomaterials, including their synthesis, proper- ties and applications, to provide a timely update and to inspire more ideas in the related research.展开更多
基金Funded by the National High Technology Research and Development Program of China(No.2007AA06Z418)the National Natural Science Foundation of China(Nos.20577036,20777058,20977070)+2 种基金the National Natural Science Foundation of Hubei Province,China(No.2015CFA137)the Open Fund of Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key Laboratory(Wuhan University)the Fund of Eco-environment Technology R&D and Service Center(Wuhan University)
文摘As efficient water treatment agents, a novel series of rectorite-based ZnO and TiO2 hybrid composites（REC/ZnO/TiO2） were synthesized and characterized in this study. Effects of experimental parameters including TiO2 mass ratio, solution p H and catalyst dosage on the removal of methyl blue（MB） were also conducted. The presence of a little mass ratio（2%-6%） of TiO2 highly promoted the photoactivity of REC/ZnO/TiO2 in removal of MB dye from aqueous solution, in which ZnO and REC played a role of photocatalyst and adsorbent. The promotion effects of TiO2 may result from the accelerated separation of electron-hole on ZnO. The observed kinetic constant for the degradation of MB over REC/ZnO and REC/ZnO/TiO2 were 0.015 and 0.038 min^（-1）, respectively. The degradation kinetics of MB dye, which followed the Langmuir–Hinshelwood model, had a reaction constant of 0.17 mg/（L min）. The decrease of removal ratio of MB after five repetitive experiments was small, indicating REC/ZnO/TiO2 has great potential as an effective and stable catalyst.
基金supported by the National Research Foundation(No.88220,and 91510)
文摘In this work, we have shown that mining waste derived Fe^3＋can be used to enhance the photocatalytic activity of TiO2. This will allow us to harness a waste product from the mines, and utilize it to enhance TiO2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO2 and biogenic jarosite. Evidence of Fe／O／Ti bonding in the TiO2/jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO2, biogenic jarosite and mechanically mixed sample of jarosite and TiO2 under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO2 nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO2 and jarosite derived Fe^3＋as was shown from the EELS and ELNEFS. Generation of OHU was supported by photoluminesence（PL） experiments.
基金partly supported by the National Natural Science Foundation of China (Grant No. 61405171)the Shandong Province Natural Science Foundation (No. ZR2012FQ014)the Shandong Province Higher Educational Science and Technology Program (No. G12LA08, No. J13LJ05)
文摘Highly ordered TiO2 nanotube arrays were fabricated via electrochemical anodization of high purity Ti foil in fluoride-containing electrolyte. The effects of applied anodization potential, anodization time on the formation of TiO2 nanotube arrays and the photocatalytic degradation of methylene blue （MB） were discussed. The TiO2 nanotube arrays calcined at 500 ℃ for 2 h show pure anatase phase. The pore diameters of TiO2 nanotube arrays can be adjusted from 30 to 90 nm using a different anodization voltage. Anodization time mainly influenced TiO2 tube length, and by increasing the anodization time, the nanotube length became longer gradually. When the anodization potential was 40 V, the average growth rate of TiO2 nanotube was about 4.17 μm/h. Both anodization potential and time had important effects on the photocatalytic efficiency. The TiO2 nanotube arrays obtained at anodization potential of 40 V for I h showed the best photocatalytic degradation ratio of MB.
基金supported by the National Natural Science Foundation of China (Nos. 21206150, U1304209 and U1204215)the Foundation for University Young Key Teacher by Henan Province (No. 2014GGJS-005)
文摘Mesoporous anatase TiO2 spheres with high surface area（119 m^2g^（-1）） were successfully synthesized via a facile and green template-free method. The prepared TiO2 was characterized by X-ray diffraction（XRD）,N2 adsorption, scanning electron microscopy（SEM）, transmission electron microscopy（TEM） and UV–vis absorbance spectra. It was found that the prepared TiO2 is characterized by pure anatase phase, which shows uniform spheres and has a typical mesostructure with a high specific surface area and a large pore volume. The effects of complexant（acetylacetone） amount, crystallization temperature and calcination temperature were also investigated. Based on the results, a sketch for the preparation of mesoporous TiO2 was proposed. First, complex formed between tetrabutyl titanate and acetylacetone in ethanol. After introduction of aqueous of ammonia sulfate and urea, hydrolysis of tetrabutyl titanate would occur slowly,and sol of TiO2 was formed. Then, crystallization proceeded under hydrothermal conditions. Calcination process favored the formation of bigger TiO2 crystal through combining of the small crystals in TiO2.This led to the formation of bigger mesopores between TiO2 crystals. Photocatalytic activity of the prepared TiO2 was evaluated by decomposition of methyl orange.
基金financially supported by the Natural Science Foundation of Jiangsu Province(No. BK20130485),(No. BK20130485)Highly Qualified Professional Initial Funding of Jiangsu University(No. 10JDG120)Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment
文摘TiO2/EDTA-rich carbon composites （TiO2/EDTA-RC） have been successfully synthesized via a low temperature carbonization process. TiO2/EDTA-RC exhibits marked absorption of visible light and excellent photoreduction of Cr（Ⅵ） activity under visible light irradiation （λ 〉 420 nm）. Due to the high carboxyl group content and strong coordination ability of EDTA, TiO2-EDTA complex can be easily fabricated between EDTA incorporated in carbon sheet and titanol group on the surface of TiO2. TiO2- EDTA complexes on the surface of TiO2/EDTA-RC, the LMCT complex, are responsible for the prominent photoreduction of Cr（Ⅵ） properties of TiO2/EDTA-RC under visible light irradiation. In addition, the unique structure of TiO2/EDTA-RC is also propitious to the visible-light photocatalytic reduction of Cr（Ⅵ）. Carbon sheet of TiO2/EDTA-RC acts as a supporter. Tio2 nanoparticles and EDTA homogeneously disperse into the carbon sheet supporter and form the TiO2-EDTA complexes, which can avoid the aggregation of TiO2 nanoparticles in the aqueous solution and provide more photocatalytic reaction points for the reduction of Cr（Ⅵ）.
基金financially supported by the National Key Project on Basic Research(No.2013CB933203)the Natural Science Foundation of China(Nos.21373224 and 21577143)+1 种基金the Natural Science Foundation of Fujian Province(Nos.2014H0054 and 2015J0544)the One Hundred Talents Program of the Chinese Academy of Sciences
文摘Pt-TiO2 nanotubes with tube diameter of -120 nm and uniformly dispersed Pt particles（size of -2 nm） were successfully synthesized via a carbon nanotube（CNT） templating method followed by a photo-deposition processing of Pt nanoparticles. The as-obtained Pt-TiO2 NTs possess both enhanced visible light absorption and reduced recombination of photogenerated electrons and holes. These merits boost the Pt-TiO2 NTs an excellent photocatalytic material toward photooxidation of a variety of low molecular hydrocarbons under atmospheric environment.
基金Funded by the National Natural Science Foundation of China(No.51478370)
文摘As a decorative material, magnesium oxychloride cement was used as a photocatalyst supporter to purify the pollutants indoors. Due to excellent adsorption properties of activated carbon（AC）, the photocatalytic composties, TiO2/AC, were prepared and introduced into the porous magnesium oxychloride cement（PMOC） substrate to composite a sort of photocatalytic cementitious material（PCM）. The optimal composite processes were assessed by gas chromatograph, using toluene as the target. By comparing the perspective of toluene purification and thorough decomposition, it can be found that the optimal mass ratio for TiO2/AC composites is 4/25, and the heat treatment to TiO2/AC sample at 350 ℃ can play the optimal synergetic role of adsorbents in photocatalytic process. The synergistic effect of TiO2, AC and magnesium oxychloride cement（MOC） was also evaluated by gas chromatograph. One-take molding process was adopted to introduce the TiO2/AC into PMOC substrate, and its optimal mass fraction was 4 wt%, while the appropriate density of substrate was 0.35 g/cm3. Toluene degradation showed that the prepared PCM can degrade pollutants efficiently. The appropriate treatment process of TiO2/AC, mass of TiO2/AC, substrate density, and stable pore structure should be coordinated to maximize the adsorption-photodegradation performance. The combination of photocatalytic materials, adsorbents, and building materials provided a new idea for the application of photocatalysis.
文摘In this article, the effects of ZiO2 surface fluorination and sulfation, on the active oxygen species formed at the reduction site in the photocatalytic process, namely O2^＊- and H2O2, were investigated from a new perspective. The superoxide radical, （O2^＊-）, was determined by colorimetry of nitroblue tetrazolium, a prominent O2^＊- scavenger. Hydrogen peroxide （H2O2） was estimated by using the iodide-starch method. In the naked TiO2 photocatalysis, O2^＊-, though less reactive, was a very important intermediate. When the TiO2 surface was fluorinated, more O2^＊- and H2O2 were produced, which indicated that the surface modification could greatly reduce the recombination of photogenerated electrons and holes, thus enhancing the photocatalytic rate. In the sulfated system, photocatalysis proceeded with a more complicated mechanism. These results added support to the view of fluoride-induced enhancement and sulfide＇s nonappreciable inhibition effect.
基金the National Natural Science Foundation of China(No.21177087)the Shanghai Environmental Protection Bureau(SEPB)Program(No.09-26)
文摘Indoor air pollutants impact human health,comfort and productivity.The method of photocatalysis has been applied mainly in flow reactors and little information is available on indoor air pollutant removal in airtight reactors.In the paper,experiments were carried out to remove formaldehyde(HCHO),ammonia(NH_3) and volatile organic compounds(VOCs)in the airtight and ventilated chambers.Results demonstrated that 90.4%of HCHO,92.3%of NH_3 and 57.9%of VOCs were removed in the amine adsorption process,while 67.5% (hereinbefore,these are the mass fraction)of HCHO,60.0%of NH_3,and 61.2%of VOCs were removed in the photocatalytic process.However,ozone-assisted photocatalytic process showed great potential to degrade indoor air pollutants in the ventilated chamber.Factors and mechanisms of the photocatalytic degradation of HCHO, NH_3 and VOCs were also discussed.
基金The financial support of Natural Sciences and Engineering Research Council of Canada (NSERC)Ontario Graduate Scholarship (OGS) programRyerson University is greatly appreciated
文摘A nitrogen-doped titanium dioxide composite photocatalyst（N–TiO2） with heterojunction structures is synthesized by three different approaches： a novel UV-assisted thermal synthesis, annealing, and microwave technique. Photocatalytic activities of synthesized photocatalysts are evaluated by the degradation of Methyl Orange under ultraviolet light types A（UV-A）, B（UV-B）, and C（UV-C）, visible light, and direct sunlight irradiation. Results show that by using N–TiO_2 photocatalyst prepared by the UV-assisted thermal synthesis and annealing, the degradation increases by 16.5% and 20.4%, respectively, compared to that by bare TiO2. The best results are obtained at a nitrogen to TiO2 mass ratio of 0.15（N：TiO2）. The enhancement of the photocatalytic activity observed in the visible range is mainly attributed to the increasing separation rate of photogenerated charge carriers. The novel UV-assisted thermal synthesis has produced encouraging results as a preparation method for the nitrogen-doped TiO2 photocatalyst; thus, further studies are recommended for process optimization, immobilization, and scale-up to evaluate its applicability in wastewater treatment.
基金Projects(51102026,51272032) supported by the Program for the National Natural Science Foundation of ChinaProject(11A014) supported by the Scientific Research Fund of Hunan Provincial Education DepartmentProject supported by the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province,China
文摘The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.
基金supported by grants from the National High Technology Research and Development Program (863) of China (Nos. 2010AA064902 and 2012AA062702)the Key Innovation Team for Science and Technology of Zhejiang Province (No. 2009R50047)
文摘It is important to develop efficient and economic techniques for removing volatile organic compounds（VOCs） in indoor air. Heterogeneous Ti O2-based semiconductors are a promising technology for achieving this goal. Anatase/brookite/rutile tricrystalline Ti O2 with mesoporous structure was synthesized by a low-temperature hydrothermal route in the presence of HNO3.The obtained samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherm. The photocatalytic activity was evaluated by photocatalytic decomposition of toluene in air under UV light illumination. The results show that tricrystalline Ti O2 exhibited higher photocatalytic activity and durability toward gaseous toluene than bicrystalline Ti O2,due to the synergistic effects of high surface area, uniform mesoporous structure and junctions among mixed phases. The tricrystalline Ti O2 prepared at R HNO3= 0.8, containing80.7% anatase, 15.6% brookite and 3.7% rutile, exhibited the highest photocatalytic activity,about 3.85-fold higher than that of P25. The high activity did not significantly degrade even after five reuse cycles. In conclusion, it is expected that our study regarding gas-phase degradation of toluene over tricrystalline Ti O2 will enrich the chemistry of the Ti O2-based materials as photocatalysts for environmental remediation and stimulate further research interest on this intriguing topic.
基金supported by research grants from Research Grant Council (GRF 478611)Innovation and Technology Commission (ITS/237/13) of Hong Kong SAR Government.P.K.supported by CAS/SAFEA International Partnership Program for Creative Research Teams of Chinese Academy of Sciences, China
文摘Photocatalysis has attracted worldwide attention due to its potential in solar energy conversion.As a ＂green＂ advanced oxidation technology, it has been extensively used for water disinfection and wastewater treatment. This article provides a review of the recent progress in solar energy-induced photocatalytic disinfection of bacteria, focusing on the development of highly efficient photocatalysts and their underlying mechanisms in bacterial inactivation. The photocatalysts are classified into Ti O2-based and non-Ti O2-based systems, as Ti O2 is the most investigated photocatalyst. The synthesis methods, modification strategies, bacterial disinfection activities and mechanisms of different types of photocatalysts are reviewed in detail.Emphasis is given to the modified Ti O2, including noble metal deposition, non-metal doping,dye sensitization and composite Ti O2, along with typical non-Ti O2-based photocatalysts for bacterial disinfection, including metal oxides, sulfides, bismuth metallates, graphene-based photocatalysts, carbon nitride-based photocatalysts and natural photocatalysts. A simple and versatile methodology by using a partition system combined with scavenging study is introduced to study the photocatalytic disinfection mechanisms in different photocatalytic systems. This review summarizes the current state of the work on photocatalytic disinfection of bacteria, and is expected to offer useful insights for the future development in the field.
基金supported by the National Natural Science Foundation of China (No. 41371472)
文摘A series of graphene–TiO2photocatalysts was synthesized by doping TiO2 with graphene oxide via hydrothermal treatment. The photocatalytic capability of the catalysts under ultraviolet irradiation was evaluated in terms of sodium pentachlorophenol（PCP-Na） decomposition and mineralization. The structural and physicochemical properties of these nanocomposites were characterized by X-ray diffraction, N2adsorption–desorption, transmission electron microscopy, scanning electron microscopy, Ultraviolet–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectra, and Fourier-transform infrared spectroscopy. The graphene–TiO2nanocomposites exhibited higher photocatalytic efficiency than commercial P25 for the degradation of PCP-Na, and 63.4% to 82.9% of the total organic carbon was fully mineralized. The improved photocatalytic activity may be attributed to the accelerated interfacial electron-transfer process and the significantly prolonged lifetime of electron-hole pairs imparted by graphene sheets in the nanocomposites. However,excessive graphene and the inhomogeneous aggregation of TiO2 nanoparticles may decrease photodegradation efficiency.
基金supported by the National Natural Science Foundation of China(No.21077117)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB05050600)the Program of the Ministry of Science and Technology of China(No.2010AA064905)
文摘Carbon-modified titanium dioxide （TiO2） was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation （PCO） of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range （〈 300℃）. However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.
基金Funded by National Basic Research Program of China(No.2009CB939704)
文摘A double-layer TiO2 nanotube arrays were formed by two-step anodization of Ti foils in different electrolytes. First, Ti in 0.5 wt% HF was anodized to form thin nanotube layer. Afterwards a second anodization was conducted in a formamide based electrolyte, which allowed the second layer of nanotube growing directly underneath the first one. From FESEM investigation we found that the thickness of second layer corresponded to the anodization time, the increasing of which would lead to the excessive etching on the first layer. The first layer protected the lower one from fluoride corrosion during anodization process. The double layer TiO2 nanotube arrays showed no benefit to photodegradation effect in methyl orange degradation experiments.
基金supported by the National Natural Science Foundation of China(no.21376102)the Natural Science Foundation of Guangdong Province,China(no.S2013010012199)
文摘TiO2 nanotubes（TNTs） with nickel sulfide（NiS） co-catalyst were prepared by a simple solvothermal method and characterized by X-ray diffraction, transmission electron microscope, N2-physisorption, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. Loading NiS nano-clusters can significantly enhance the photocatalytic H2 evolution performance of TNTs. The optimum NiS loading content was found to be 8 wt% and the corresponding hydrogen production rate is ca. 7486 μmol/h/g, being about 79 times higher than that of pure TNTs. This enhancement of photocatalytic H2 evolution was attributed to the synergistic effect between NiS and TNTs.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB36000000)the National Natural Science Foundation of China(21590811,21777167,21827809)and the National Key R&D Program of China(2018YFA0209302).
文摘Bothβ-andγ-hydroxyketone structures are important units in biologically active molecules,synthetic drugs and fine chemicals.Although there are some routes available for their manufacture from pre-functionalized groups on one or two matrix molecule(s),the approaches to simply and simultaneously deposit two oxygen atoms from dioxygen into two specific C(sp^(3))positions of pure saturated hydrocarbons have rarely succeeded because they are involved in the targeted activation of three inert C–Hσbonds all at once.Here,we show that a TiO_(2)-CH_(3)CN photocatalytic suspension system enables the insertion of dioxygen into one C(sp^(3))–C(sp^(3))bond of strained cycloparaffin derivatives,by which difunctionalized hydroxyketone products are obtained in a one-pot reaction.With the cleavage event to release strain as the directional driving force,as-designed photocatalytic reaction systems show 21 examples ofβ-hydroxyketone products with 31%–76%isolated yields for three-membered ring derivatives and 5 examples ofγ-hydroxyketone products with 30%–63%isolated yields for four-membered ring substrates.^(18)O isotopic labeling experiments using^(18)O2,Ti^(18)O_(2) and intentionally added H218O,respectively,indicated that both oxygen atoms of hydroxyketone products were exclusively from dioxygen,suggesting a previously unknown H^(+)/TiO_(2)-e−catalyzed arrangement pathway of the hydroperoxide intermediate to convert dioxygen into hydroxyketone units.
基金support from the U.S. National Science Foundation (DMR-1609061)the College of Arts and Science,University of Missouri-Kansas CityUniversity of Missouri Research Board
文摘Photocatalysis has been regarded as one of best solutions to using the sunlight to produce hydrogen from water and to removing organic pollutants from the environment, and titanium dioxide （TiO2） nanomate- rials have been treated as the primary photocatalyst for these purposes. However. their large band gap has largely limited the activity to the UV region of the solar spectrum. The discovery of black TiO2 in 2011 has triggered world-wide research interests with new hope to overcome this problem. This review briefly summarizes the recent progresses of black TiO2 nanomaterials, including their synthesis, proper- ties and applications, to provide a timely update and to inspire more ideas in the related research.
