氮掺杂Bi2O3光催化剂的制备及其可见光催化性能

以硝酸铋和六次甲基四胺为原料,采用沉淀法合成了不同氮掺杂量的Bi2O3(N-Bi2O3)粉体,并采用XRD、FT-IR、XPS、UV-Vis、PL手段对其晶相结构和光谱特征等进行了表征.研究结果表明,未掺杂Bi2O3为单斜相α-Bi2O3,氮掺杂Bi2O3则为四方相β-Bi2O3和Bi5O7NO3组成的混晶,氮原子替代了Bi2O3晶格中部分氧原子,形成了Bi N键而稳定存在.氮掺杂能促进β-Bi2O3的生成.与未掺杂Bi2O3粉体相比,氮掺杂样品的吸收带边发生了明显红移,荧光强度明显减弱.甲基橙在可见光下的降解实验表明,氮掺杂Bi2O3具有良好的可见光催化活性.     

Bi_2S_3-BiOCl/煤矸石复合光催化剂的制备及光催化性能

以表面改性煤矸石粉、Bi(NO_3)_3·5H_2O和NH_4Cl为原料,采用超声化学法制备了BiOCl/煤矸石前驱体;并通过BiOCl/煤矸石前驱体和硫代乙酰胺(TAA)的阴离子交换反应,原位制备了Bi_2S_3-BiOCl/煤矸石复合光催化剂。利用XRD和SEM对Bi_2S_3-BiOCl/煤矸石复合光催化材料的结构及表面形貌进行了表征,并以可见光为光源,甲基橙为目标降解物,对其光催化活性进行了研究。结果表明:在可见光辐照下,Bi_2S_3-BiOCl/煤矸石复合光催化剂表现出较高的光催化降解能力,这是由于Bi_2S_3与BiOCl复合后形成的异质结促进了光生电子和光生空穴的分离,抑制了它们的复合。     

纳米Ag包覆Bi_2O_3颗粒的制备及其可见光催化性能评价

本文采用两步合成工艺,通过化学共沉淀工艺制备β-Bi_2O_3纳米颗粒;经室温原位还原硝酸银,制备不同包覆量纳米Ag负载的Bi_2O_3(Ag/β-Bi_2O_3)光催化剂颗粒。对该光催化剂进行结构表征,并以甲基橙溶液模拟废水在可见光下评价其光催化性能。透射电子显微镜(TEM)测试表明纳米Ag均匀包覆于β-Bi_2O_3颗粒表面,其中β-Bi_2O_3聚集体的颗粒尺寸约30nm,而分散的纳米Ag晶体约为20nm。紫外可见光谱(UV-vis)谱图表明Ag/β-Bi_2O_3复合材料的带隙能比纯相Bi_2O_3要小,对可见光利用率相应增加,光催化性能随之增强。其中以2.0%(质量比)Ag包覆β-Bi_2O_3颗粒的光催化性能最佳。     

Preparation and modification of hierarchical nanostructured Bi2WO6 with high visible light-induced photocatalytic activity

Hierarchical nanostructured Bi(2)WO(6) micro-clews were synthesized by a solvothermal process with mixed solvents and formaldehyde. The hierarchical Bi(2)WO(6) micro-clews, with an average diameter of ca. 1.0 μm, consisted of nano-sheets assembled in a special fashion and the formation process mainly went through an Ostwald ripening-anisotropic growth and self-assembling process. The Bi(2)WO(6) micro-clews were further modified by Bi(2)O(3) to fabricate heterojunction photocatalysts, where Bi(2)O(3) nanoparticles were uniformly assembled on the surface of Bi(2)WO(6) nano-sheets. Compared with pure Bi(2)WO(6) and Bi(2)O(3), the composite photocatalyst exhibits higher photocatalytic activity for the degradation of rhodamine B under visible light. On the basis of characterization by x-ray diffraction, photoluminescence and UV-vis diffuse reflectance spectroscopies, a mechanism was proposed to account for the enhanced photocatalytic activity of the Bi(2)O(3)/Bi(2)WO(6) heterojunction.     

Efficient degradation of tetrabromobisphenol A by heterostructured Ag/Bi5Nb3O15 material under the simulated sunlight irradiation

Heterostructured metallic silver-layered bismuth niobate two-component system (Ag/Bi(5)Nb(3)O(15)) was developed for the first time by a mild hydrothermal method combined with photodeposition. The Ag/Bi(5)Nb(3)O(15) exhibited single-crystalline orthorhombic structure with small particle size (50-200 nm) and octahedral as well as sheet-like shape; additionally, it possessed photoresponse in both UV and visible region. As a novel alternative photocatalysts to TiO(2), the photocatalytic activity of the Ag/Bi(5)Nb(3)O(15) was evaluated by the degradation of tetrabromobisphenol A, a member from the family of the brominated flame retardant, under solar simulating Xe lamp irradiation, and enhanced photocatalytic activity in compared to Bi(5)Nb(3)O(15) itself and Degussa P25 was obtained.     

Synergetic effects of Bi5+ and oxygen vacancies in Bismuth(Ⅴ)-rich Bi4O7 nanosheets for enhanced near-infrared light driven photocatalysis

The appropriate energy level position of photocatalysts dominates the photocatalytic redox reaction and utilization efficiency of solar energy for wastewater treatment.Herein,we report a near-infrared(NIR)light driven Bi5+-rich Bi4O7 photocatalyst,achieving a greatly enhanced photocatalytic activity for pollutant removal compared with Bi3+-replenished Bi2O3.Density functional theory calculations show the formation of an intermediate band in the Bi4O7 structure because of the hybridization of O 2p and Bi 4s orbits.The formation of the intermediate band not only narrows the band gap but also improves the optical absorption property and separation efficiency of the photoinduced carriers.The existence of the oxygen vacancies(OVs)in the Bi4O7 nanosheets ensures high carriers'concentration,which is verified by the Hall effect test.The synergetic effects of the OVs and Bi5+greatly accelerate the separation efficiency of the photogenerated carriers.Consequently,the Bi4O7 nanosheets exhibit enhanced NIR light driven photocatalytic activity for the degradation of rhodamine B and ciprofloxacin compared with the bulk Bi2O3.This study paves the way to the design of highly efficient NIR light-responsive Bi-based photocatalysts for environmental purification.     

改进溶液燃烧法制备Fe3+掺杂Bi24O31Cl10及其光催化性能的研究

采用改进溶液燃烧法,以硝酸铋、柠檬酸、氯化铵和硝酸铁为原材料制备Fe-Bi24O31Cl10光催化物质,并通过在可见光下降解RhB评价Fe^3+掺杂对其光催化性能的影响。采用XRD,XPS,UV-vis,SEM,HTEM,FT-IR等表征手段研究了不同Fe^3+掺杂量对Bi24O31Cl10的物相、元素价态、光吸收性能、微观形貌以及颗粒分布、晶面间距、化学结构组成等的影响。结果表明:掺杂Fe^3+未改变Bi24O31Cl10的物相,片状形貌,但其片状大小明显变小且厚度变薄,光吸收性能增强,光生电子-空穴复合率下降,与纯Bi24O31Cl10相比,Fe^3+掺杂能显著提高Bi24O31Cl10的光催化活性,当Fe^3+掺杂量为0.5%(摩尔分数)时,对Bi24O31Cl10的光催化性能促进最高,在可见光下光照50 min,对RhB的脱色率可达75%,较纯Bi24O31Cl10提高了44%。     

Impact of Pt loading methods over mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystal on photocatalytic dye-sensitized H2 production activity

In this work, the photocatalytic water splitting under visible light irradiation for hydrogen production was investigated by using Eosin Y-sensitized Pt-loaded mesoporous-assembled TiO₂–ZrO₂ mixed oxide nanocrystal photocatalysts. The mesoporous-assembled TiO₂–ZrO₂ mixed oxide with the TiO₂-to-ZrO₂ molar ratio of 95:5 (i.e. 0.95TiO₂–0.05ZrO₂) was synthesized by using a sol–gel process with the aid of a structure-directing surfactant. The Pt loading was comparatively performed via two different effective methods: single-step sol–gel (SSSG) and photochemical deposition (PCD). The synthesized photocatalysts were methodically characterized by N₂ adsorption–desorption, XRD, UV–visible spectroscopy, SEM–EDX, TEM–EDX, TPR, and H₂ chemisorption analyses. The results revealed that the Pt loading by the PCD method greatly enhanced the photocatalytic hydrogen production activity of the synthesized mesoporous-assembled 0.95TiO₂–0.05ZrO₂ mixed oxide photocatalyst more than that by the SSSG method. The optimum Pt loading by the PCD method was experimentally observed at 0.5 wt.%, which was well associated with the maximum Pt dispersion. In addition, the PCD conditions, i.e. UV light irradiation time and UV light intensity, were investigated and optimized to be 2 h and 44 W, respectively.     

Hydrangeas-like Bi2WO6: facile synthesis, visible-light driven photocatalysis and theoretical analysis

Hydrangeas-like Bi2WO6 powders were synthesized successfully by salt-ultrasonic assisted hydrothermal process, which were characterized by scanning electron microscopy (SEM), Energy dispersive X-ray (EDS), X-ray diffraction (XRD), and UV-visible diffuse reflectance spectra (UV-Vis DRS), respectively. Bi, W and O elements were contained in the product, which could be tested by EDS. The crystal structure of the catalyst was orthorhombic phase (JCPDS card no.73-1126). And the band gap was estimated to be 2.56 eV from the onset of UV-Vis absorption spectra of the catalyst. In addition, the photocatalytic activities of the products were investigated on the degradation of Rhodamine B (RhB). It demonstrated that photocatalysts exhibited excellent visible-light driven photocatalytic performance. And the target residue was less than 1% in 20 min under Xenon lamp irradiation. First-principles calculations based on density functional theory (DFT) were used to explore the electronic and optical properties of Bi2WO6. And the theoretical calculations could illustrate the photocatalytic performance of Bi2WO6 powders under visible light irradiation.     

Controlled growth of vertically oriented hematite/Pt composite nanorod arrays: use for photoelectrochemical water splitting

Highly ordered and vertically grown Pt-doped α-Fe(2)O(3) nanorod arrays on a gold substrate were successfully prepared by the electrochemical co-deposition method using an anodized aluminum oxide template. The effect of the Pt doping in α-Fe(2)O(3) nanorod arrays on their water splitting ability was investigated for the first time. The elemental maps obtained by energy dispersive spectroscopy showed that the Pt was uniformly dispersed in the α-Fe(2)O(3) nanorod arrays. The photoelectrochemical properties of the α-Fe(2)O(3)/Pt composite nanorod arrays as a function of the Pt content were studied by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5 100 mW cm(-2) illumination. The Pt-doped α-Fe(2)O(3) nanorod arrays show an improvement in solar-to-hydrogen conversion efficiency (～5%) for photoelectrochemical water splitting compared to undoped samples. To the best of our knowledge, it is the highest value yet obtained from α-Fe(2)O(3).     

钼掺杂的铌钙酸的合成及光催化性能研究

通过高温固相反应合成了钼掺杂的铌钙酸钾系列,并通过离子交换反应制备出钼掺杂的铌钙酸系列,采用X射线衍射、紫外-可见漫反射光谱、扫描电镜等对所制得的样品进行了表征.在甲醇为电子给体、Pt为助催化剂的情况下,研究了钼掺杂的铌钙酸系列催化剂,在波长＞290nm紫外光辐射下分解水产氢的光催化活性,结果表明钼的掺杂有效地提高了铌钙酸的光催化活性,并讨论了引起催化剂活性差异的原因.     

Construction of hierarchical nanostructured TiO2/Bi2MoO6 heterojunction for improved visible light photocatalysis

In this study, Bi2MoO6 hollow microspheres were modified by depositing TiO2 nanoparticles through a simple hydrothermal method. The prepared TiO2/Bi2MoO6 photocatalysts were characterized by scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic performance of the heterostructured catalysts was evaluated by degradation of methylene blue (MB) under visible-light irradiation (lambda>420 nm). The photocatalysts based on nanostructured Bi2MoO6 and TiO2 exhibit much higher photocatalytic activity than the single-phase Bi2MoO6 or TiO2 and the mechanical mixture of Bi2MoO6 and TiO2 for degradation of MB under the same conditions. The results reported in this study provide insight into constructing other heterostructured photocatalysts.     

Recent advances in earth-abundant photocatalyst materials for solar H2 production

Harvesting solar energy attracts great attention due to its abundant, clean, and permanent characteristics. Thus, photocatalysts have emerged as promising candidates for converting the solar energy to practically useful hydrogen molecules. Tremendous efforts have been devoted in developments of efficient photocatalysts for water splitting, but most of photocatalysts utilize noble metals to improve photocatalytic performance. Progress in photocatalyst materials for the hydrogen production coupled with a better understanding of the basic catalytic mechanisms has enabled better selection of catalytic nanomaterials with improved performance. In this review, we analyze the current state of the art in photocatalyst materials for photochemical hydrogen production through water splitting using earth-abundant materials. We also explore two main factors involved in both material morphology and sacrificial agent to further improve the activity, efficiency and stability of photocatalysts.     

简易合成Bi/Bi2MoO6/TiO2复合纳米纤维及其增强的可见光催化性能

以电纺TiO₂ 纳米纤维为基质, 葡萄糖为还原剂, 采用简单一步溶剂热法制备了等离子体Bi/Bi₂MoO₆/TiO₂复合纳米纤维。利用X射线衍射、场发射扫描电镜、透射电子显微镜、X射线光电子能谱、紫外-可见漫反射光谱和光致发光谱等对样品进行表征。以RhB和4-CP为模拟有机污染物, 评价材料的光催化性能。结果表明: 部分Bi ³⁺被葡萄糖还原成金属Bi纳米粒子, 原位沉积在Bi₂MoO₆纳米片上, 同时构筑在TiO₂纳米纤维表面。金属Bi的等离子体共振效应, 有效提高了样品的光催化活性。可见光照50 min, 样品对RhB的降解率为95.8%, 五次循环后仍保持在92%以上; 可见光照180 min, 样品对4-CP的降解率达68.8%。证实该材料具有良好的可见光催化活性和稳定性。     

Visible light photocatalytic H₂-production activity of CuS/ZnS porous nanosheets based on photoinduced interfacial charge transfer

Visible light photocatalytic H(2) production through water splitting is of great importance for its potential application in converting solar energy into chemical energy. In this study, a novel visible-light-driven photocatalyst was designed based on photoinduced interfacial charge transfer (IFCT) through surface modification of ZnS porous nanosheets by CuS. CuS/ZnS porous nanosheet photocatalysts were prepared by a simple hydrothermal and cation exchange reaction between preformed ZnS(en)(0.5) nanosheets and Cu(NO(3))(2). Even without a Pt cocatalyst, the as-prepared CuS/ZnS porous nanosheets reach a high H(2)-production rate of 4147 μmol h(-1) g(-1) at CuS loading content of 2 mol % and an apparent quantum efficiency of 20% at 420 nm. This high visible light photocatalytic H(2)-production activity is due to the IFCT from the valence band of ZnS to CuS, which causes the reduction of partial CuS to Cu(2)S and thus enhances H(2)-production activity. This work not only shows a possibility for substituting low-cost CuS for noble metals in the photocatalytic H(2) production but also for the first time exhibits a facile method for enhancing H(2)-production activity by photoinduced IFCT.     

Bi2O3-Bi2WO6 直接Z-scheme异质结的制备、表征及光催化还原U(VI)的性能

根据能带理论,以Bi(NO₃)₃·5H₂O为铋源,采用水热煅烧法制备了Bi₂O₃-Bi₂WO₆复合光催化材料,SEM、XRD、XPS、紫外可见漫反射(UV-vis DRS)、电化学阻抗(EIS)等表征手段对材料进行表征与分析,以U(VI)为目标污染物,在可见光下进行光催化还原U(VI)的性能研究。结果表明:与纯Bi₂WO₆相比,Bi₂O₃-Bi₂WO₆复合材料具有较高的光催化活性,当Bi₂O₃与Bi₂WO₆的摩尔比为2.4∶1时,Bi₂O₃-Bi₂WO₆的光催化活性最好,光催化活性增强归因于Bi₂O₃的加入,在Bi₂O₃与Bi₂WO₆界面形成的直接Z-scheme异质结,提高了光生电子-空穴的传输速率,降低了其复合率;另一方面,Bi₂O₃的加入使Bi₂WO₆带隙变小,扩大对可见光的响应范围,从而提高了Bi₂O₃-Bi₂WO₆光催化剂的活性。本研究为设计和合成具有高可见光活性的光催化剂和了解增强U(VI)光催化还原机理提供了新的思路。      

Pt/Fe_2O_3/TiO_2的制备、表征及其光催化活性研究

报道了担载不同贵金属或过渡金属氧化物的TiO2 催化剂对空气中微量甲醛的光催化氧化的研究结果。实验发现 ,TiO2 上担载Fe2 O3 或Pt时对甲醛均有较高的光催化氧化活性。同时担载双组分的光催化剂Pt Fe2 O3 TiO2 ,由于 2种组分的协同作用 ,具有更高的光催化活性。研究了催化剂制备因素、催化剂的结构及表面特性对催化活性的影响     

Template-free preparation of non-metal (B,P,S) doped g-C3N4 tubes with enhanced photocatalytic H2O2 generation

Developing environmentally friendly methods to produce hydrogen peroxide (H2O2) has received increas-ing attention.Photocatalysis has been proved to be a sustainable technology for H2O2 production.Herein,the novel non-metal elements (B,P,and S) doped g-C3N4 tubes (B-CNT,P-CNT,and S-CNT) photocata-lysts were obtained via a hydrothermal synthesis followed by thermal polymerization.By adjusting the precursor,the yield of g-C3N4 tubes (CNT) materials has been greatly improved.The as-prepared B-CNT,P-CNT,and S-CNT photocatalysts show an enhanced photocatalytic H2O2 production with the formation rate constants values of 42.31 μM min-1,24.95μM min-1,and 24.22μM min-1,respectively,which is higher than that of bulk CN (16.40 μM min-1).The doped B,P,S elements significantly enhanced the photocatalytic activity by adjusting their electronic structures and promoting the separation of electron-hole carriers.The results have shown great potential for the practical application of CNT photocatalysts.     

BiNbO4纳米棒的制备及光催化性能研究

采用共沉淀法制备BiNbO4纳米棒。利用X射线粉末衍射仪(XRD)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis DRS)和热重分析(TG/DTA)对其结构、形貌和性质进行表征,并通过紫外-可见分光光度计分析BiNbO4纳米棒光降解罗丹明B来研究其光催化活性。结果表明以五氧化二铌和五水硝酸铋为原料制备得到正交相结构的BiNbO4纳米棒;BiN-bO4纳米棒具有较高的光催化活性,在紫外光下,pH值=3.05,催化剂用量为2g/L时能够有效地降解罗丹明B,降解率受到光源、催化剂浓度和溶液pH值的影响较大。     

Facile synthesis of defected TiO2-x (B) nanosheet/graphene oxide hybrids with high photocatalytic activity

TiO2 (B) nanosheets/GO (graphene oxide) hybrids are considered to be outstanding performance pho-tocatalysts for high efficiency of H2 evolution.However,they still suffer severe challenges during the synthetic processes,such as a large amount of the capping agents adhering on the surface and easy occurrence of aggregation.To figure out these obstacles,Ar plasma treatment as a modified method in this study not only enable the TiO2 (B) nanosheets distributed uniformly on the GO sheets but also engi-neer defects within TiO2 (B) nanosheetsto significantly improve the photocatalytic activity for the water splitting.The hydrogen evolution rate of the TiO2-x (B)/GO sheets is 1.4 times higher compared with that of original TiO2 (B)/GO sheets without Ar plasma treatment.The improved photocatalytic proper-ties were owing to the synergetic effects of oxygen vacancies and the heterojunction between GO and TiO2 (B),which can promote the visible light utilization and accelerate separation and transportation of photogenerated electron-holes.This study can provide a facile pathway to prepare the two-dimensional hybrid photocatalysts with high photocatalytic H2 activity.