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.

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.

Photocatalytic performance of TiO_2 immobilized on polystyrene (PS) thin film for mineralization of pollutants

A new photocatalyst, TiO_2 powder immobilized on polystyrene (PS) thin films,was prepared using a novel method and its photocatalytic activity on the photodegradation ofacridine dye in aqueous solution was tested. By this method, the crystal form and grain size of theimmobilized TiO_2 were well maintained. Compared with TiO_2 powder, the photocatalytic activity ofTiO_2/PS thin films was not significantly reduced. The catalyst is stable and can be reused severaltimes without the loss of activity, which makes wastewater treatment using this photocatalyticdegradation technique of this way possible in the practical application.

Preparation and Properties of Lanthanum Trivalent Ion Doped TiO_2 Nanopowders by Liquid Plasma Spray

The lanthanum trivalent ion doped TiO2 nanopowders were prepared by liquid plasma spray with solution of titanium tetra-tert-butoxide and alcohol as feedstock and La(NO3)3·6H2O as doping component. The photocatalytic activity of samples at different doping concentrations in photocatalytic degradation of methyl orange was discussed. The powders were characterized by Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD), and the effect of doped ion on the pattern, phase composition and crystallite sizes were analyzed. The results indicated that lanthanum trivalent ion doped TiO2 nanopowders could be prepared by liquid plasma spray. Lanthanum trivalent ion doping increased the photocatalytic activity of TiO2 greatly, the optimal doping concentration was 0.5%. The doped powders were the mixture of anatase phase and rutile phase. The contents of anatase phase decreased firstly and then increased with an increase in the contents of lanthanum trivalent ion. Doping lanthanum trivalent ion could make the TiO2 nanopowders uniform and reduced its particle size.

活性炭负载TiO_2光催化降解1-萘胺

用活性炭载TiO2 (TiO2 /C)催化剂光催化降解1 萘胺。在用XRD、SEM、比表面积、亚甲蓝吸附值、二氧化钛的负载量对TiO2 /C催化剂进行表征的基础上,考察了催化剂用量、溶液的pH值、1-萘胺的初始浓度等因素对1 萘胺降解率的影响。结果表明,在溶液的pH=7 .10、TiO2 /C光催化剂用量为1 .0g、1 萘胺溶液浓度为1 .40×10-3 mol/L,光照时间为2. 5h时, 1 萘胺的降解率可达80%。

光催化剂TiO_2改性的研究进展

较低的光量子效率是限制TiO2 光催化技术实用化的主要原因 ,改性是提高TiO2 光量子效率的重要手段。文中综述了近年来TiO2 改性几种主要方法如贵金属沉积、复合半导体、离子掺杂、光敏化、表面还原处理、表面螯合及衍生方面研究所取得的进展 ,对改性机理进行了分析 ,并评价了各种方法改性的效果。

提高废水处理中TiO_2光催化活性途径的探讨

TiO2 光催化剂以其无毒、催化活性高、氧化能力强、稳定性好等特点被广泛应用于光催化处理技术中。根据近年来TiO2 光催化技术的研究成果 ,对如何提高TiO2

反胶束体系中有机染料PDS对TiO_2纳米粒子的表面修饰

The TiO2 nanoparticles were modified by phthalocyanine dinuclear sulphate（PDS）. The results showed that a, the adsorption intensity of PDS in UV-Vis spectrum increased with increase in water content in / ratio; b, in AOT/isooctane reverse micelle system the UV-Vis spectral peak intensity for PDS decreased, broadened and redshifted with increase in concentration of TiO2 in TiCl4 solution, and the fluorescence spectral intensity for PDS decreased and then gradually to quenching also with increase in TiO2 concentration.

光促CO_2和乙烯合成丙烯酸ZnO-TiO_2催化剂的研究

摘要采用溶胶凝胶法制备了复合半导体光催化材料ZnO-TiO2,并用热分析(DTATG)、X射线衍射(XRD)、透射电子显微术(TEM)、BET比表面测试(BET)、程序升温还原(TPR)、红外吸收光谱(IR)、紫外可见漫反射光谱(UVvis)及多相光催化反应等实验技术对其晶体结构、表面组成、吸附性能、吸光性质以及光催化反应性能进行了表征和评价。实验结果表明,制得的催化剂粒径处于10~20nm之间,比表面积为725m2/g,晶体结构以锐钛矿型TiO2为主;ZnO和TiO2复合后,Zn2+进入氧四面体和八面体中心,形成Zn2-TiO4晶相,提高了250~400nm范围光的吸收强度;在常压、100℃条件下可以实现CO2与C2H4的光催化合成反应,CO2转化率为028%,生成丙烯酸的选择性超过70%。

Design and fabrication of self-suspending aluminum-plastic/semiconductor photocatalyst devices for solar energy conversion

The design and synthesis of self-suspending photocatalyst device with easy recyclability is important for practical application.Here,this work utilizes aluminum-plastic package waste as raw material to prepare an aluminum-plastic supported TiO_(2)(AP-TiO_(2))photocatalyst device through 3D printing design and surface deposition method.A series of characterizations were carried out to explore the structure,morphology and performance of the AP-TiO_(2)device.Under UV light illumination,the AP-TiO_(2)-50 efficiently degrade 93.6%tetracycline hydrochloride(THC)after 4 hr,which increases by 8.3%compared with that of TiO_(2)powder suspension system with the same catalyst amount.Based on it,AP-ZnO,AP-CdS,AP-g-C_3N_4and AP-Pt-TiO_(2)are also fabricated,and applied in photocatalytic degradation and hydrogen evolution,which all exhibit higher photoactivities than powder suspension systems.This work provides a new avenue for the fabrication of advanced recyclable photocatalyst device.Moreover,the work offers a novel sight for the high-value utilization of aluminum-plastic package waste,which has positive implications for environmental protection.

Constructing extrinsic oxygen vacancy on the surface of photocatalyst as CO_(2)and electrons reservoirs to improve photocatalytic CO_(2)reduction activity

Constructing own oxygen vacancies in the photocatalysts is a very promising method to improve their photocatalytic CO_(2)reduction activity.However,some catalysts have excellent stabilities,making it difficult for them to construct their own oxygen vacancies.To simplify the above difficulty of stable photocatalysts,constructing extrinsic oxygen vacancies on their surface as a novel idea is proposed.Here,a stable TiO_(2)nanosheet is chosen as a research object,we uniformly deposited BiOCl quantum dots on their surface via a simple adsorption-deposition method.It is found that BiOCl quantum dots are able to simultaneously self-transform into defective BiOCl with many oxygen vacancies when the photocatalyst is performed photocatalytic CO_(2)reduction.These extrinsic oxygen vacancies can act as“CO_(2)and photo-generated electrons reservoirs”to improve CO_(2)capture and accelerate the separation of photogenerated electrons and holes.For the above reasons,the modified TiO_(2)showed obvious enhancement of photocatalytic CO_(2)reduction compared to pristine TiO_(2)and BiOCl.This work may open a new avenue to broaden the use of oxygen vacancies in the process of photocatalytic CO_(2)reduction.

Enhanced photocatalytic ammonia oxidation activity and nitrogen selectivity over Ag/AgCl/N-TiO_(2) photocatalyst

The removal of ammonia(NH_(3))emitted from agricultural and industrial activities is of great significance to protect human health and ecological environment.Photocatalytic NH_(3)oxidation to N2under mild conditions is a promising strategy.However,developing visible light photocatalysts for NH_(3)oxidation is still in its infancy.Here,we fabricate N-TiO_(2)and Ag/AgCl/N-TiO_(2)photocatalysts by sol-gel and photodeposition methods,respectively.The introduction of N not only endows TiO_(2)with visible light response(absorption edge at460 nm)but also results in the formation of heterophase junction(anatase and rutile).Thus,N-TiO_(2)shows 2.0 and 1.8 times higher than those over anatase TiO_(2)and commercial TiO_(2)for NH_(3)oxidation under full spectrum irradiation.Meanwhile,surface modification of Ag can simultaneously enhance visible light absorption(generating localized surface plasmon resonance effect)and charge separation efficiency.Therefore,the photocatalytic activity of Ag/AgCl/N-TiO_(2)is further improved.Furthermore,the presence of N and Ag also enhances the selectivity of N2product owing to the change of reaction pathway.This work simultaneously regulates photocatalytic conversion efficiency and product selectivity,providing some guidance for developing highly efficient photocatalysts for NH_(3)elimination.

Synthesis of core-shell nanostructured SiO_(2)/TiO_(2)photocatalysts via atomic layer deposition in a fluidized bed with central tube

Fluidized bed atomic layer deposition is an efficient technique for particle coating with precise control over the film thickness and uniformity at the sub-nanoscale.In this study,a fluidized bed with a central tube is designed,where the central tube has two roles:improve fluidization and deliver precursors separately.The synthesis of core-shell structured SiO_(2)/TiO_(2)nanoparticle catalysts for photodegradation of tetracycline hydrochloride(TC)is carried out using TiCl_(4)and H_(2)O as precursors at 180℃under atmospheric pressure.Under the combination of vibration and central tube,the segregation of agglomerate size along the bed height is weakened,and the prepared SiO_(2)/TiO_(2)nanoparticles show excellent photocatalytic degradation performance:the degradation efficiency on TC is 96%under 300 W xenon lamp irradiation for 60 min.The mechanism of enhanced photocatalytic activity is due to the Ti-O-Si bonds generated at the interface,which increase the ability to absorb sunlight and accelerate the separation of holes and electrons.

Facile one-pot hydrothermal method to prepare Sn(Ⅱ) and N co-doped TiO_(2) photocatalyst for water splitting under visible light irradiation

In this paper,a visible light-responsive Sn^(2+)and N co-doped TiO_(2)photocatalyst was prepared by facile one-pot hydrothermal method.All as-prepared samples were characterized in detail by a series of characterization approaches.The results showed that the Sn^(2+)and N elements were co-doped into TiO_(2),while the catalyst still maintains anatase crystal structure and gets irregular little nanocluster in diameter of 9–10 nm with higher specific surface area.The absorption edge of Sn^(2+)and N co-doped TiO_(2)extends to the visible light region.Compared with Sn^(2+)-doped TiO_(2)and N-TiO_(2),the absorption edges have obvious red-shift of about 50 and 70 nm,respectively.The synergistic effect of O 2p-N 2p and O 2p-Sn 5s hybridization to form impurity levels is the main reason for the red-shift.The hydrogen production performance of the Sn^(2+)and N co-doping TiO_(2)(n(N)/n(Ti)=1)catalyst reached the maximum value of 0.37 mmol·h^(-1)·g^(-1)under visible light,which is higher than that of N-doped TiO_(2)and SnTiO_(2)-doped TiO_(2)singly.This result is due to the wider visible light region-responsive ability of Sn^(2+)and N codoped into TiO_(2).Furthermore,mild hydrothermal methods will not make the Sn^(2+)oxidized to Sn^(4+),which make the catalysts still maintain high photocatalytic performance.This work provides a simple and mild method for the preparation of dual-element co-doped TiO_(2)with high crystallinity,excellent performance and broad application prospects.

Comparative study of metal oxides and phosphate modification with different mechanisms over g-C_(3)N_(4) for visible-light photocatalytic degradation of metribuzin

In this work,a comparative study of three frequently employed modification techniques to g-C_(3)N_(4)(CN)nanosheets for the photocatalytic degradation of metribuzin(MET)under visible-light irradiation has been carried out in detail.The modification methods were coupling TiO_(2)nanoparticles(TO)as electron acceptors,nano-sized Fe_(2)O_(3)(FO)to construct a Z-scheme nanocomposite,and phosphate(HP)modification to promote O_(2)adsorption.The steady-state and transient-state surface photovoltage spectra and transient photoluminescence(PL)spectra confirmed that all the three modification techniques enhanced the charge separation with prolonged lifetimes and presented degradation activities in the order of TO/CN[FO/CN[HP/CN.The TO/CN nanocomposite showed the highest photocatalytic activity for MET degradation,with a sixfold higher rate than bulk CN.Liquid chromatography–tandem mass spectrometry and radical trapping experiments indicated that the increased activity was related to the synergetic effect of two radicals(·O^(2-) and ·OH)involved in the photocatalytic degradation pathway,which was different from the·OH radical-dominated pathway of bulk CN.This work reveals the importance of charge separation and the influence of the radical pathway and provides guidance for the design of high-efficiency photocatalysts.

Ordered macroporous structured TiO_(2)-based photocatalysts for CO_(2)reduction:A review

Herein,we review the significant of ordered macroporous(OM)TiO_(2)-based catalysts for boosting pho-tocatalytic CO_(2)reduction.Based on the need to improve the three key factors of photogenerated charge separation eficiency,solar energy utilization and CO_(2)adsorption rate during the conversion of CO_(2)to H_(2)O,we summarized five modification measures:including doping ions into OM TiO_(2),introducing sec-ond semiconductor coupling and noble metal nanoparticles for fabricating multiple Z-scheme heterojunc-tions,constructing hierarchical pore and carbon-loaded OM TiO_(2)materials,which effectively enhance the absorption rate of visible light,the separation rate of electrons-hole pairs and the selection of multiple active sites.The OM structured TiO_(2)-based photocatalysts solve the single or multiple key factors for en-hancing photocatalytic performances during CO_(2)conversion.The catalytic mechanism and pathways of OM structured TiO_(2)-based photocatalysts for CO_(2)reduction are discussed and summarized.It provides new insights on the development of high-efficient catalyst for photocatalytic CO_(2)conversion to solar fu-els.

All-inorganic TiO_(2)/Cs_(2)AgBiBr_(6) composite as highly efficient photocatalyst under visible light irradiation

In recent years, limited photocatalysis efficiency and wide band gap have hindered the application of TiO_(2) in the field of photocatalysis. A leading star in photocatalysis has been revealed as lead-free Cs_(2)AgBiBr_(6) double halide perovskite nanocrystals, owing to its strong visible light absorption and tunable band gap. In this work, this photocatalytic process was facilitated by a unique TiO_(2)/Cs_(2)AgBiBr_(6) composite, which was identified as an S-cheme heterojunction. TiO_(2)/Cs_(2)AgBiBr_(6) composite was investigated for its structure and photocatalytic behavior. The results showed that when the perovskite dosage is 40%, the photocatalytic rate of TiO_(2) could be boosted to 0.1369 min^(-1). This paper discusses and proposes the band gap matching, carrier separation, and photocatalytic mechanism of TiO_(2)/Cs_(2)AgBiBr_(6) composites, which will facilitate the generation of new ideas for improving TiO_(2)’s photocatalytic performance.

Controlled synthesis of Pt-loaded yolk-shell TiO_(2)@SiO_(2) nanoreactors as effective photocatalysts for hydrogen generation

Yolk-shell and hollow structures are powerful platforms for controlled release,confined nanocatalysis,and optical and electronic applications.This contribution describes a fabrication strategy for a yolk-shell nanoreactor(NR)using a post decoration approach.The widely studied yolk-shell structure of silica-coated TiO_(2)(TiO_(2)@SiO_(2))was used as a model.At first,anatase TiO_(2) spheres were prepared,and subsequently were given a continuous coating of carbonaceous and silica layers.Finally,the carbonaceous layer was removed to produce a yolk-shell structure TiO_(2)@SiO_(2).By using an in-situ photodeposition method,Pt-encased spheres(Pt-TiO_(2)@SiO_(2))were synthesized with Pt nanoparticles grown on the surface of the TiO_(2) core,which contained void spaces suitable for use as NRs.The NR showed enhanced hydrogen production with a rate of 24.56 mmol·g^(-1)·h^(-1) in the presence of a sacrificial agent under simulated sunlight.This strategy holds the potential to be extended for the synthesis of other yolk-shell photocatalytic NRs with different metal oxides.

Surface-modified Ag@Ru-P25 for photocatalytic CO_(2) conversion with high selectivity over CH_(4) formation at the solid–gas interface

Systematic optimization of the photocatalyst and investigation of the role of each component is important to maximizing catalytic activity and comprehending the photocatalytic conversion of CO_(2) reduction to solar fuels.A surface-modified Ag@Ru-P25 photocatalyst with H_(2)O_(2) treatment was designed in this study to convert CO_(2) and H_(2)O vapor into highly selective CH4.Ru doping followed by Ag nanoparticles(NPs)cocatalyst deposition on P25(TiO_(2))enhances visible light absorption and charge separation,whereas H_(2)O_(2) treatment modifies the surface of the photocatalyst with hydroxyl(–OH)groups and promotes CO_(2) adsorption.High-resonance transmission electron microscopy,X-ray photoelectron spectroscopy,X-ray absorption near-edge structure,and extended X-ray absorption fine structure techniques were used to analyze the surface and chemical composition of the photocatalyst,while thermogravimetric analysis,CO_(2) adsorption isotherm,and temperature programmed desorption study were performed to examine the significance of H_(2)O_(2) treatment in increasing CO_(2) reduction activity.The optimized Ag1.0@Ru1.0-P25 photocatalyst performed excellent CO_(2) reduction activity into CO,CH4,and C2H6 with a~95%selectivity of CH4,where the activity was~135 times higher than that of pristine TiO_(2)(P25).For the first time,this work explored the effect of H_(2)O_(2) treatment on the photocatalyst that dramatically increases CO_(2) reduction activity.

稀土La掺杂TiO_(2)纳米纤维高响应光催化降解染料研究

为了提高TiO_(2)光催化性能,并研究金属离子掺杂对TiO_(2)光催化性能的影响,采用静电纺丝技术和煅烧工艺制备稀土元素La掺杂TiO_(2)无机纳米纤维膜,通过SEM、XRD、FT-IR、TG测试对材料的形貌、结构进行表征,以亚甲基蓝为靶向降解剂,进一步深入研究La^(3+)改性TiO_(2)光催化氧化降解染料的机理。结果表明,当染料浓度为10 mg/L,La^(3+)掺杂改性纳米TiO_(2)纤维的浓度为15 mg/10 mL条件下,催化10 min的降解率为63.41%,催化70 min的降解率即可达到99.87%,比未掺杂TiO_(2)纳米纤维的降解率提高了6.36%,可见,La^(3+)的掺杂提高了TiO_(2)光催化降解速率,所需要的时间减少了。