BiOCl/UiO‐66 composite with enhanced performance for photo‐assisted degradation of dye from water

Semiconductor‐based photocatalysis is an environmental friendly and cost‐effective technique for water treatment. Due to their unique properties, metal–organic frameworks (MOFs) are considered as ideal platform to develop composite photocatalyst. In this study, Bismuth oxychloride (BiOCl) was first attempt to be incorporated with highly stable MOFs, UiO‐66(Zr) by hydrothermal reaction. Different characterization methods including X‐ray diffraction, Scanning electron microscopy, Fourier transform infrared spectroscope, X‐ray photoelectron spectroscopy had been used to prove the successful synthesis of composite photocatalyst. The resultant BiOCl/UiO‐66 composite showed higher photodegradation performance of Rhodamine B (RhB) under ultraviolet and visible light irradiation than that of pristine materials and their mechanically mixed sample. In addition, the composite exhibited good structural stability and reusability. The photocatalytic mechanism of RhB degradation over the composite under visible light proceeded via a photosensitization process. A better adsorptivity of RhB and effective electron transfer within the hybrid material might be responsible for the enhanced photocatalytic performance.     

Environmentally benign chitosan as precursor and reductant for synthesis of Ag/AgCl/N-doped carbon composite photocatalysts and their photocatalytic degradation performance

In this study, we reported a novel Ag/AgCl loaded N-doped carbon composite photocatalyst (Ag/AgCl/NC) which was fabricated by a facile and green method. The composite was prepared only by two simple steps. Firstly, the Ag/N-doped carbon (Ag/NC) was prepared by one-step hydrothermal treatment; during this progress the environmentally benign and renewable natural chitosan was used as not only reducer and stabilizer, but also as a nitrogen source and carbon source. Secondly, Ag/AgCl/NC composite was synthesized via in situ oxidation reaction by adding FeCl₃. The Ag/AgCl/NC composite was characterized using X-ray diffraction, transmission electronic microscopy, energy dispersive X-ray spectra, UV-visible diffused reflectance spectra, X-ray photoelectron spectroscopy and nitrogen adsorption-desorption measurements, respectively. The obtained Ag/AgCl/NC composite exhibited a superior photocatalytic activity and stability for the degradation of rhodamine B (RhB) under visible light irradiation.     

碳纳米管改性g-C3N4提升可见光催化降解性能

以尿素为原料,引入少量的多壁碳纳米管(CNT)改性,采用简便方法制备CNT/g-C_3N_4催化剂。利用扫描电镜(SEM)、透射电镜(TEM)、傅里叶红外光谱仪(FT-IR)、X射线衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见-近红外分光光度计(UV-Vis-NIR Spectrophotometer)、荧光光谱(PL)等手段对CNT/g-C_3N_4催化剂进行表征。结果表明,g-C_3N_4与CNT之间的协同作用,影响了gC_3N_4的能带结构,增强了其对可见光的吸收,改善了光生载流子的分布,提高了电子-空穴对的分离效率。并以罗丹明B(RhB)水溶液模拟废水,在可见光下考察催化剂的光催化降解性能,发现当CNT掺杂量为0.1%(w/w)时效果最佳,降解速率常数是体相g-C_3N_4的3.1倍,且研究发现超氧自由基是该体系下的主要活性物种。     

银-溴化银/麦羟硅钠石可见光催化剂的制备及其光催化性能

利用离子交换法将AgBr负载到水热合成的麦羟硅钠石(magadiite,MD)载体上,通过光照还原生成新型Ag-AgBr/MD复合光催化剂;采用X射线衍射仪、扫描电镜、透射电镜分析了复合催化剂的结构,采用紫外-可见分光光度计评价了AgBr负载量和pH对复合催化剂可见光催化降解罗丹明(RhB)水溶液活性的影响.结果表明,随着AgBr负载量的增加,RhB的降解率先增大后减小,随pH的增大RhB的降解率减小.当n(AgNO3)∶n(MD)=2∶1,pH=9时,复合光催化剂具有较强的光吸收性能,且AgBr高度分散在载体MD表面,因而对RhB的光催化降解性能最高.     

Enhanced photocatalytic performance of carbon quantum dots/BiOBr composite and mechanism investigation

Novel CQDs/BiOBr composite photocatalysts are constructed via a simple hydrothermal synthesis and show superior activity in photocatalytic degradation of organic pollutants.     

多壁碳纳米管负载TiO_2复合器件可见光光催化降解RhB

采用溶胶-凝胶法制备了多壁碳纳米管(MWCNTs)负载的ITO/MWCNTs-TiO2/ITO复合器件,利用SEM、XPS、UV-Vis光谱等技术对复合样品进行形貌和结构表征,以液相罗丹明B(RhB)的可见光光催化降解为探针反应,评价MWCNTs-TiO2复合薄膜的催化活性.XPS结果表明MWCNTs与TiO2之间没有形成Ti-C键.I-V特性表明负载了MWCNTs的ITO/MWCNTs-TiO2/ITO复合器件的光电流增强.与空白TiO2薄膜相比,MWCNTs-TiO2复合薄膜的可见光光催化降解RhB的速率提高了3.2倍.MWCNTs并没有掺杂到TiO2晶格中,而是起到了类似光敏剂的作用,可在可见光激发下将导带电子转移到TiO导带上,经一系列反应降解RhB有机物.     

铬取代杂多阴离子PW11O39Cr（Ⅲ）（H2O）4-可见光催化降解罗丹明B

为了利用太阳光能去除水体有机染料污染物,以Keggin型铬取代杂多阴离子PW11O39Cr(III)(H2O)4-(PW11Cr)为光催化剂, 详细研究在可见光照射下PW11Cr对水体有机染料污染物罗丹明B(RhB)的光催化降解作用, 考察RhB和PW11Cr初始浓度以及溶液pH对RhB可见光催化降解速率的影响, 并通过可见吸收光谱和荧光发射光谱研究水溶液中PW11Cr和RhB的相互作用, 提出PW11Cr光催化作用的机理. 实验结果表明,含有50 μTTmol·L-1 PW11Cr和10 μTTmol·L-1 RhB的水溶液在200 W可见光下照射120 min, RhB的降解率达到100%,总有机碳去除率约32%. 在PW11Cr浓度较大和pH<3.5的酸性条件下, PW11Cr与RhB之间易发生络合, 导致RhB光降解速率变慢,而PW11Cr浓度为50 μTTmol·L-1和溶液接近中性条件下, RhB的光降解速率较快.     

高效Ag@AgBr等离子体光催化剂的制备及可见光活性研究

采用水热法和光致还原法制备了具有等离子体共振效应的Ag@AgBr可见光催化剂,利用XRD,SEM,EDX,DRS和XPS等手段对产物的结构和性能进行表征,并研究了催化剂在可见光下对罗丹明B(RhB)的光催化降解性能,考察了催化剂的循环使用及捕获剂对Ag@AgBr光催化性能的影响.结果表明:贵金属Ag纳米粒子的表面等离子体共振效应可显著增强Ag@AgBr对可见光的吸收;催化剂对罗丹明B具有较高的可见光降解活性和稳定性,在可见光下照射90 min,对罗丹明B的降解率达95%以上,光催化剂循环使用5次仍具有良好的光催化降解活性;淬灭实验表明在Ag@AgBr降解罗丹明B过程中,吸附在催化剂表面的h+、·OH、O2·-是主要的活性物种.     

Keggin型铬取代杂多阴离子/D301R可见光催化性能

将Keggin型铬取代磷钨杂多阴离子PW11O39Cr(Ⅲ)(H2O)4-(PW11Cr)负载于弱碱性阴离子交换树脂D301R表面,制备了固体光催化剂PW11Cr/D301R,并以模型污染物罗丹明B(RhB)的降解为探针评估了该催化剂的可见光催化活性,讨论了光催化反应机理,同时考察了催化剂剂量、溶液pH值和溶液中常见离子对RhB可见光催化降解反应的影响以及催化剂的稳定性。 实验结果表明,当PW11Cr/D301R的剂量为100 mg时,10 μmol/L RhB水溶液暴露在200 W金卤灯下进行照射,RhB完全降解所需的时间仅为30 min,比PW11Cr均相体系缩短了3倍;反应180 min总有机碳(TOC)去除率约为84%。 催化剂剂量、溶液pH值和溶液中存在的Cl-、SO2-4和PO3-4对RhB光催化降解反应的速率均有一定影响。 催化剂循环实验显示经循环使用7次后催化剂的活性几乎没有损失。     

Mercury oxide as an efficient photocatalyst for degradation of rhodamine B dye under visible-light irradiation

In this work, a new visible-light-responsive photocatalyst, mercury oxide (HgO) was successfully developed. Its activity is significantly higher than that of the highly efficient photocatalyst, Ag₃PO₄ in degradation of rhodamine B (RhB) dye under irradiation of visible light. The HgO photocatalyst can be reused for at least three cycles without obvious loss of its activity in the degradation experiments. It was found that the RhB degradation rate is significantly influenced by the dye solution pH. The ultrahigh photocatalytic activity of HgO is attributed to its strong oxidization-ablility of the photogenerated holes, and high separation-possibility of the photogenerated carriers.     

InOOH纳米晶的控制合成及其液相光催化性能

以硝酸铟作为前驱体,在蒸馏水和乙二胺的混合溶剂中制备出了InOOH纳米晶,详细地考察了反应溶剂及温度对终产物的影响。利用X射线粉末衍射(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)、扫描电子显微镜(SEM)和透射电镜(TEM)对样品的晶相结构、光吸收性质及其形貌进行了详细的表征。考察了样品在紫外光下及可见光下对液相中的染料罗丹明B(RhB)的光催化降解性能。发现InOOH在紫外光下可以彻底分解RhB,而在可见光下只能使RhB脱色。InOOH在紫外光和可见光下对RhB的分解遵循两种不同的反应机制。     

Keggin型铜取代磷钨杂多阴离子可见光催化降解罗丹明B

以Keggin型铜取代杂多阴离子PW11O39Cu(Ⅱ)(H2O)5-[PW11Cu]为可见光催化剂,有机染料罗丹明B(RhB)为模型污染物,研究了在可见光照射下PW11Cu对RhB的可见光催化降解作用,提出了PW11Cu可见光催化作用的反应机理,同时考察了RhB初始浓度、PW11Cu初始浓度和溶液pH值对RhB光催化降解速率的影响。 实验结果表明,含有15.6 μmol/L PW11Cu+10 μmol/L RhB的水溶液在可见光照射下反应80 min,RhB的降解率达100%,总有机碳去除率约33%。 RhB的可见光催化降解服从准一级动力学方程,在RhB初始浓度为20、30和40 μmol/L的情况下,其表观一级速率常数分别为3.1×10-2、2.0×10-2和1.5×10-2 min-1。     

Fabrication of nanoporous polymeric crystalline TiO2 composite for photocatalytic degradation of aqueous organic pollutants under visible light irradiation

A nanoporous polymeric crystalline TiO₂ composite (TiO₂/PDVB‐MA) has been successfully synthesized through an in situ synthesis method using divinylbenzene (DVB), methacrylic acid (MA) and tetrabutyl titanate. The experimental results showed that TiO₂ nanoparticles composed of the mixture phases of anatase and rutile were homogeneously dispersed into the PDVB‐MA support. The TiO₂/PDVB‐MA composite was used as photocatalyst for Rhodamine B (RhB), bisphenol A and 2,4,6‐trichlorophenol degradation under visible light irradiation. More interestingly, the excellent photocatalytic performance of the composite was observed with regard to RhB and bisphenol A, which might be ascribed to the synergistic effect between TiO₂ nanoparticles and PDVB‐MA. Moreover, TiO₂/PDVB‐MA composite could be recycled at least four times in the removal of RhB, suggesting that it is a promising photocatalyst to catalyze the degradation of organic pollutants under visible light irradiation.     

增强可见光催化活性的Z型MoO3/Bi2O4复合光催化剂的制备（英文）

全球工业化进程的加快使人们饱受环境污染问题的困扰.半导体光催化技术作为一种高效、绿色、有潜力的新技术,在环境净化方面有着广阔的应用前景.Bi2O4是近年来新开发出的一种铋基光催化剂,在环境净化方面已有一些研究.但是,单体光催化剂通常存在光响应范围窄、光生载流子复合率高等问题,这些不足限制了Bi2O4的进一步应用.因此,需要通过适当的改性来拓宽其光响应范围和提高其载流子的分离效率,从而提高其光催化活性.构建Z型异质结被认为是提高光催化剂光生载流子分离效率并进一步提高光催化活性的有效方法.MoO3是一种宽禁带的n型半导体,具有独特的能带结构、光学特性和表面效应,是一种非常有前景的半导体光催化剂.虽然MoO3材料的光生载流子复合率高,带隙(2.7-3.2 eV)大,不利于其参与光催化反应,但MoO3与其他合适的半导体配位形成复合材料后能够有效提高其光生载流子的分离效率,从而提高其光催化活性.本研究采用简单的水热法制备了一种新型Z型MoO3/Bi2O4复合光催化剂,SEM和TEM分析结果表明,MoO3和Bi2O4紧密结合在一起.X射线光电子能谱分析表明,MoO3和Bi2O4之间存在很强的界面相互作用,这有助于电荷转移和光生载流子的分离.光致发光光谱、电阻抗和光电流测试也证明了MoO3/Bi2O4复合光催化剂的光生载流子分离效率更高,形成了更强的光电流.通过在可见光下降解RhB溶液评价了所合成光催化剂的光催化性能.15%MoO3/Bi2O4(15-MB)复合光催化剂表现出了最佳的可见光催化活性,在40 min内对10 mg/L RhB溶液的降解率达到了99.6%,其降解速率是Bi2O4的2倍.此外,15-MB复合光催化剂在经过五次循环降解RhB溶液后仍保持良好的光催化活性和稳定性,表明MoO3/Bi2O4复合光催化剂具有较强的应用潜力.通过自由基捕获实验确定了光催化反应中主要的活性自由基为 O2-和h+.通过莫特-肖特基测试和带隙计算得到MoO3和Bi2O4的价带和导带位置.最后,根据实验和分析结果提出了Z型MoO3/Bi2O4复合光催化剂在可见光下降解RhB溶液的机理.本研究为设计铋基Z型异质结光催化剂用于高效去除环境污染物提供了一种有前景的策略.     

Construction of SnS2–SnO2 heterojunctions decorated on graphene nanosheets with enhanced visible‐light photocatalytic performance

Heterostructures formed by the growth of one kind of nanomaterial in/on another have attracted increasing attention due to their microstructural characteristics and potential applications. In this work, SnS₂–SnO₂ heterostructures were successfully prepared by a facile hydrothermal method. Due to the enhanced visible‐light absorption and efficient separation of photo‐generated holes and electrons, the SnS₂–SnO₂ heterostructures display excellent photocatalytic performance for the degradation of rhodamine (RhB) under visible‐light irradiation. Additionally, it is found that the introduction of graphene into the heterostructures further improved photocatalytic activity and stability. In particular, the optimized SnS₂–SnO₂/graphene photocatalyst can degrade 97.1% of RhB within 60 min, which is about 1.38 times greater than that of SnS₂–SnO₂ heterostructures. This enhanced photocatalytic activity could be attributed to the high surface area and the excellent electron accepting and transporting properties of graphene, which served as an acceptor of the generated electrons to suppress charge recombination. These results provide a new insight for the design and development of hybrid photocatalysts.     

Chemical‐Bond‐Mediated p–n Heterojunction Photocatalyst Constructed from Coordination Polymer Nanoparticles and a Conducting Copolymer: Visible‐Light Active and Highly Efficient

A visible‐light‐active p–n heterojunction photocatalyst has been synthesized by the enwrapping of poly[aniline‐co‐N‐(4‐sulfophenyl)aniline] ( PAPSA ) on a coordination polymer nanoparticle ( NCP ). Compared with the visible‐light‐inactive NCP , the new p–n heterojunction photocatalyst, PAPSA/NCP , exhibits a much higher efficiency in the reduction of Cr^VI under visible light. PAPSA performs two functions in this p–n heterojunction photocatalyst. First, as a visible‐light‐active material, it extends the photoresponse region of the photocatalyst from the ultraviolet to the visible‐light region. Secondly, as a p‐type semiconductor possessing suitable energy levels with respect to NCP , PAPSA forms a p–n heterojunction with the n‐type NCP ; the inner electric field of the p–n heterojunction accelerates the separation of electrons and holes, which enhances the photocatalytic efficiency. Furthermore, the p–n heterojunction photocatalyst exhibits outstanding stability during the photocatalytic reduction of Cr^VI.     

纳米Ag@AgBr表面敏化K_2Ti_4O_9可见光催化剂的微波合成、表征和光催化活性(英文)

利用微波法合成纳米尺寸Ag@AgBr表面敏化K2Ti4O9的复合光催化剂(Ag@AgBr/K2Ti4O9),并通过SEM、X-射线能量色散谱(EDX)、TEM、选定区域电子衍射(SAED)、XRD、紫外-可见漫反射(UV-VisDiffuseReflectance)、XPS等对其进行了表征,同时在可见光下测定催化剂对有机物降解的光催化活性。结果表明,粒径为0.2~0.5μm的Ag@AgBr均匀分散在K2Ti4O9表面,Ag@AgBr/K2Ti4O9对可见光有很好的吸收且Ag@AgBr的担载量影响可见光的吸收。当Ag@AgBr的担载量为25wt%时,复合光催化剂具有最高的光催化活性,光照1h对罗丹明B(RhB)的降解率可达97%。另外,催化剂的担载量和稳定性也做了考察。催化剂较高的光催化活性主要归因于Ag纳米粒子的表面等离子体效应和有效的光生电子-空穴的分离。     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载Cd Mo O4光催化剂。运用X射线粉末衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱(UV-Vis DRS)和X射线光电子能谱(XPS)等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对Cd Mo O4紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与Cd Mo O4相比,Ag/Cd Mo O4具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O2-·和·OH是光催化降解过程的主要活性物种。     

Ag负载CdMoO4光催化剂的制备及其催化性能

采用硼氢化钠还原法制备了Ag负载CdMoO₄光催化剂。运用X射线粉末衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等测试手段对催化剂的组成和结构进行了表征;采用紫外-可见漫反射光谱（UV-Vis DRS）和X射线光电子能谱（XPS）等技术对催化剂的光响应和表面状态进行了分析,考察了不同Ag负载量对CdMoO₄紫外光降解罗丹明B和可见光选择性氧化苯甲醇性能的影响。结果表明,与CdMoO₄相比,Ag/CdMoO₄具有更高的光催化活性。利用活性物种捕获实验探讨其光催化降解过程的反应机理,实验结果显示O₂^-·和·OH是光催化降解过程的主要活性物种。     

薄膜表面等离子体光催化剂Ag@AgBr/CNT/Ni的制备和性能

用复合电沉积技术制备了Ag@AgBr/CNT/Ni表面等离子体薄膜催化剂,以扫描电镜（SEM）、X射线衍射（XRD）、拉曼光谱（Raman Spectra）、X射线光电子能谱（XPS）和紫外-可见漫反射光谱（UV-Vis DRS）对薄膜的表面形貌、晶体结构、化学组成和光谱特性进行了表征,在可见光照射下,用罗丹明B（RhB）作为模拟污染物对薄膜的光催化性质和稳定性进行测定,采用测定薄膜电化学阻抗谱（EIS）和向反应系统中加入活性物种捕获剂的方法对薄膜光催化机制进行探索。结果表明：最优工艺下制备的Ag@AgBr/CNT/Ni薄膜是由少量碳纳米管（CNT）和表面沉积纳米Ag粒子的AgBr晶体构成的复合薄膜。薄膜具有突出的表面等离子体共振效应、优异的光催化活性和良好的催化稳定性。光催化罗丹明B 20 min,Ag@AgBr/CNT/Ni薄膜的降解率是Ag@AgBr/Ni薄膜的1.32倍,是P25 TiO₂/ITO多孔薄膜的21.6倍。在保持光催化性能基本不变的前提下可循环使用5次。CNT的存在使薄膜电荷传导性能和光催化还原溶解氧的性能大幅增加,是所制薄膜相对于Ag@AgBr/Ni薄膜光催化性能提高的主要原因。提出了薄膜光催化罗丹明B的反应机理。