银掺杂TiO_2纳米管阵列的制备及可见光光电催化性能研究

采用电化学阳极氧化法在含Fˉ有机电解液体系中制备出高度有序、管径70nm、管长3~5μm掺银的TiO2纳米管阵列.考察了相关的工艺参数（电解液组成、时间、电压）对TiO2纳米管阵列形貌的影响.以SEM和XRD等技术对样品进行形貌和结构表征.采用目前文献报道较少的Ag对TiO2纳米管阵列进行掺杂,并以EDS和XRD对样品进行分析.以甲基橙溶液为目标降解物,考察不同条件下各样品的光催化性能.

用化学需氧量指数法研究亚甲基蓝的可见光光电催化脱色反应机理

以玻璃碳(GC)为基底材料,采用电化学沉积法结合连续化学浴沉积法制备了CuInSe2/Ag3PO4@AgIO4/GC复合光电极,并利用此电极研究了亚甲基蓝(MB)的可见光光电催化脱色反应过程.通过监测反应体系紫外-可见吸收光谱、水相红外吸收光谱和化学需氧量指数(COD)等变化对其脱色反应机理进行了研究.结果表明,在固定可见光辐照时间、强度和光电极受光面积的条件下,当光电极外加偏压设为0.61 V(vs. SCE), H2O2促进剂的初始浓度为0.42 mmol/L, 0.15 mol/L Na2SO4支持电解质的pH为2.7时,对0.050 mmol/L的亚甲基蓝溶液光电催化降解45 min时其脱色率与矿化率的比值为8.5;并观察到伴随MB分子的脱色反应过程逐渐有少量有机沉淀产物生成,表明MB经光电催化脱色反应后其分子的吩噻嗪母核结构仅发生了部分降解,但并未彻底矿化为无机物;结合紫外和红外光谱实验结果提出了光电催化MB脱色反应的机理.

In_2O_3敏化ZnO纳米棒阵列的性能及其光电催化活性

以掺氟SnO2(FTO)导电玻璃为基底,采用水热法制备了ZnO纳米棒阵列.通过In(NO3)3水溶液水洗的方法,合成了In2O3敏化ZnO纳米棒阵列光催化剂.采用场发射扫描电子显微镜(FESEM),X射线能谱(EDX),X射线衍射(XRD)及紫外-可见漫反射光谱(UV-VisDRS)对样品的形貌、结构、组成、晶相等进行一系列的表征.以罗丹明B(RhB)为目标降解物,探究了In2O3敏化ZnO纳米棒阵列光电催化活性.采用场诱导表面光伏技术(FISPV)研究了不同含量的In2O3敏化ZnO纳米棒阵列在光照射下的光生电荷行为.结合电化学工作站检测不同样品的光电流,随着In2O3敏化量的改变,光电流和开路电压也随之改变.并探讨了In2O3敏化ZnO纳米棒阵列光生电荷行为与光电催化活性之间的关系.结果表明,适量In2O3敏化的ZnO光催化剂在可见光下2h内对罗丹明B的降解效率达到95%,是单纯ZnO纳米棒阵列的2.4倍.

In situ fabrication of CdMoO4/g-C3N4 composites with improved charge separation and photocatalytic activity under visible light irradiation

To further improve the charge separation and photocatalytic activities of g-C3N4 and CdMoO4 under visible light irradiation,CdMoO4/g-C3N4 composites were rationally synthesized by a facile precipitation-calcination procedure.The crystal phases,morphologies,chemical compositions,textural structures,and optical properties of the as-prepared composites were characterized by the corresponding analytical techniques.The photocatalytic activities toward degradation of rhodamine B solution were evaluated under visible light irradiation.The results revealed that integrating CdMoO4 with g-C3N4 could remarkably improve the charge separation and photocatalytic activity,compared with those of pristine g-C3N4 and CdMoO4.This would be because the CdMoO4/g-C3N4 composites could facilitate the transfer and separation of the photoexcited electron-hole pairs,which was confirmed by electrochemical impedance spectroscopy,transient photocurrent responses,and photoluminescence measurements.Moreover,active species trapping experiments demonstrated that holes(h+)and superoxide radicals(?O2?)were the main active species during the photocatalytic reaction.A possible photocatalytic mechanism was proposed on the basis of the energy band structures determined by Mott-Schottky tests.This work would provide further insights into the rational fabrication of composites for organic contaminant removal.

A comparison study of alkali metal-doped g-C_3N_4 for visible-light photocatalytic hydrogen evolution

Photocatalytic hydrogen production based on semiconductor photocatalysts has been considered as one of the most promising strategies to resolve the global energy shortage.Graphitic carbon nitride(g‐C3N4)has been a star visible‐light photocatalyst in this field due to its various advantages.However,pristine g‐C3N4usually exhibits limited activity.Herein,to enhance the performance of g‐C3N4,alkali metal ion(Li+,Na+,or K+)‐doped g‐C3N4are prepared via facile high‐temperature treatment.The prepared samples are characterized and analyzed using the technique of XRD,ICP‐AES,SEM,UV‐vis DRS,BET,XPS,PL,TRPL,photoelectrochemical measurements,photocatalytic tests,etc.The resultant doped photocatalysts show enhanced visible‐light photocatalytic activities for hydrogen production,benefiting from the increased specific surface areas(which provide more active sites),decreased band gaps for extended visible‐light absorption,and improved electronic structures for efficient charge transfer.In particular,because of the optimal tuning of both microstructure and electronic structure,the Na‐doped g‐C3N4shows the most effective utilization of photogenerated electrons during the water reduction process.As a result,the highest photocatalytic performance is achieved over the Na‐doped g‐C3N4photocatalyst(18.7?mol/h),3.7times that of pristine g‐C3N4(5.0?mol/h).This work gives a systematic study for the understanding of doping effect of alkali metals in semiconductor photocatalysis.

Facile fabrication of ZnIn2S4/SnS2 3D heterostructure for efficient visible-light photocatalytic reduction of Cr（Ⅵ）

Photocatalytic method has been intensively explored for Cr(VI)reduction owing to its efficient and environmentally friendly natures.In order to obtain a high efficiency in practical application,efficient photocatalysts need to be developed.Here,ZnIn2S4/SnS2 with a three-dimensional(3D)heterostructure was prepared by a hydrothermal method and its photocatalytic performance in Cr(VI)reduction was investigated.When the mass ratio of SnS2 to ZnIn2S4 is 1:10,the ZnIn2S4/SnS2 composite exhibits the highest photocatalytic activity with 100%efficiency for Cr(VI)(50 mg/L)reduction within 70 min under visible-light irradiation,which is much higher than those of pure ZnIn2S4 and SnS2.The enhanced charge separation and the light absorption have been confirmed from the photoluminescence and UV-vis absorption spectra to be the two reasons for the increased activity towards photocatalytic Cr(VI)reduction.In addition,after three cycles of testing,no obvious degradation is observed with the 3D heterostructured ZnIn2S4/SnS2,which maintains a good photocatalytic stability.

Unique electronic structure of Mg/O co-decorated amorphous carbon nitride enhances the photocatalytic tetracycline hydrochloride degradation

g-C3N4 is a hot visible light photocatalyst. However, the fast recombination of photogenerated electron- hole pairs leads to unsatisfactory photocatalytic efficiencies. In this study, Mg/O co-decorated amorphous carbon nitride (labeled as MgO-CN) with a unique electronic structure was designed and prepared via a combined experimental and theoretical approach. The results showed that the MgO-CN exhibited an increased light absorption ability and promoted charge separation efficiency. The Mg and O co-decoration created a unique structure that could generate localized electrons around O atoms and enhance the reactant activation capacities via the C→O←Mg route. This could dramatically promote the O2 molecule activation on the catalyst surface to generate reactive species (?O2 –/?OH). The optimized MgO-CN exhibited a high photocatalytic activity for the degradation of tetracycline hydrochloride in water, which was five times higher than that of pristine g-C3N4. The present work could provide a new strategy for modifying the electronic structure of g-C3N4 and enhancing its performance for environmental applications.

Co-MOF as an electron donor for promoting visible-light photoactivities of g-C3N4 nanosheets for CO2 reduction

A possible mechanism for boosting the visible-light photoactivities of graphitic carbon nitride(g-C3N4)nanosheets for CO2 reduction via coupling with the electron donor Co-metal-organic framework(MOF)is proposed in this study.Specifically,Co-MOF as an electron donor is capable of transferring the photogenerated electrons in the lowest unoccupied molecular orbital(LUMO)to the conduction band of g-C3N4 to facilitate charge separation.As expected,the prepared Co-MOF/g-C3N4 nanocomposites display excellent visible-light-driven photocatalytic CO2 reduction activities.The CO production rate of 6.75μmol g–1 h–1 and CH4 evolution rate of 5.47μmol g–1 h–1 are obtained,which are approximately 2 times those obtained with the original g-C3N4 under the same conditions.Based on a series of analyses,it is shown that the introduction of Co-MOF not only broadens the range of visible-light absorption but also enhances the charge separation,which improves the photocatalytic activity of g-C3N4 to a higher level.In particular,the hydroxyl radical(·OH)experiment was operated under 590 nm(single-wavelength)irradiation,which further proved that the photogenerated electrons in the LUMO of Co-MOF can successfully migrate to g-C3N4.This work may provide an important strategy for the design of highly efficient g-C3N4-based photocatalysts for CO2 reduction.

Novel Bi2MoO6 Nanosheets/Vertical TiO2 Nanorods Arrays Heterojunction with Enhanced Photoelectrochemical Performance under Visible Light Irradiation

Novel Bi2MoO6/TiO2 heterojunction was fabricated by growing Bi2MoO6 nanosheets arrays on the vertically aligned TiO2 nanorods arrays via a two-step solvothermal method. The obtained Bi2MoO6/TiO2 hierarchical heterojunction showed excellent visible light photoelectrochemical performance. Compared with the pure TiO2 and Bi2MoO6, the photocurrent density of the heterojunction was increased 57 and 29 times, respectively. Furthermore, the hydrogen generation rate of the Bi2MoO6/TiO2 for photoelectrocatalytic water-splitting was about 6 times higher than that of the pure Bi2MoO6. The improved performance can be attributed to the synergistic effects of enhanced absorption of visible light, increase of migration rate and separation efficiency of photo-induced carriers.

Propylene Polymerization Catalysts with Sulfonyl Amines as Internal Electron Donors

Three sulfonyl aliphatic amines [（R2SO2）2NR1, viz.： compound 1, in which RI=Me, and R2=Ph; compound 2, in which R1=n-Bu, and R2=CF3; and compound 3, in which RI=C8H17, and R2=CF3], have been synthesized and employed as internal electron donors （IED） for the preparation of Ziegler-Natta catalysts for the polymerization of propylene. The contents of Ti, H and C in these catalysts have been determined by elemental analysis and UV-vis spectrophotometry. The effect of the structure and dosage of the electron donor, the A1/Ti ratio and the polymerization temperature on the catalyst performance has been studied. Under optimized conditions, the catalyst with a highest activity yielded polypropylene with high isotacticity in the absence of external electron donors.

Maximizing the visible light photoelectrochemical activity of B/N-doped anatase TiO_2 microspheres with exposed dominant {001} facets

Anatase TiO2 microspheres with exposed dominant {001} facets were doped with interstitial boron to have a concentration gradient with the maximum concentration at the surface. They were then further doped with substitutional nitrogen by heating in an ammonia atmosphere at different temperatures from 440 to 560℃ to give surface N concentrations ranging from 7.03 to 15.47 at%. The optical absorption, atomic and electronic structures and visible-light photoelectrochemical water oxidation activity of these materials were investigated. The maximum activity of the doped TiO2 was achieved at a nitrogen doping temperature of 520℃ that gave a high absorbance over the whole visible light region but with no defect-related background absorption.