Investigation of photoelectrocatalytic degradation mechanism of methylene blue by a-Fe_(2)O_(3) nanorods array

Efficiently and thoroughly degrading organic dyes in wastewater is of great importance and challenge.Herein,vertically oriented mesoporous a-Fe_(2)O_(3)nanorods array(a-Fe_(2)O_(3)-NA)is directly grown on fluorine-doped tin oxide(FTO)glass and employed as the photoanode for photoelectrocatalytic degradation of methylene blue simulated dye wastewater.The Ovsites on the a-Fe_(2)O_(3)-NA surface are the active sites for methylene blue(MB)adsorption.Electrons transfer from the adsorbed MB to Fe-O is detected.Compared with electrocatalytic and photocatalytic degradation processes,the photoelectrocatalytic(PEC)process exhibited the best degrading performance and the largest kinetic constant.Hydroxyl,superoxide free radicals,and photo-generated holes play a jointly leading role in the PEC degradation.A possible degrading pathway is suggested by liquid chromatography-mass spectroscopy analysis.This work demonstrates that photoelectrocatalysis by a-Fe_(2)O_(3)-NA has a remarkable superiority over photocatalysis and electrocatalysis in MB degradation.The in-depth investigation of photoelectrocatalytic degradation mechanism in this study is meaningful for organic wastewater treatment.

Effects of Magnetic Field on Photodegradation of Methylene Blue over ZnO and TiO2 Powders using UV-LED as a Light Source

The magnetic field effects （MFEs） are studied on photocatalytic degradation of methylene blue （MB） solution using ZnO and TiO2 particles. The UV-VIS-NIR spectrometer is used to monitor the MB concentrations, and the dependence of the reaction rate on the initial dye concentration and settling duration is studied under UV light irradiation. It is found that the MFEs exist on the heterogeneous reaction systems for both ZnO and TiO2 powders and that the extraordinary phenomenon is reproducible. For ZnO powder, the results are in good agreement with the second-order reaction kinetics following the Langmuir-Hinshelwood （L-H） model, while the reaction for TiO2 follows first-order kinetics. It enhances the photodegradation for ZnO, while it reduces or enhances the reaction for TiO2 depending on the initial dye concentrations. The MFEs become small or negligible when the same photodecomposition experiment is carried out after settling the MB solution for more than three hours for both ZnO and TiO2. It is suggested that the key factors of MFEs on photocatalytic degradation is the condition of the MB solution as well as the characteristics of photocatalysts. The alteration of the MFEs ascribed to the solution condition caused by variation of the settling time.

Structural, Optical and Photocatalytic Properties of Cu2+ Doped ZnO Nanorods with Using HMTA Solvent Prepared by Hydrothermal Method

In this experiment, Cu2+ doped ZnO (Cu-ZnO) nanorods materials have been fabricated by hydrothermal method. Cu2+ ions were doped into ZnO with ratios of 2, 5 and 7 mol.% (compared to the mole’s number of Zn2+). The hexamethylenetetramine (HMTA) solvent used for the fabrication of Cu-ZnO nanorods with the mole ratio of Zn2+:HMTA = 1:4. The characteristics of the materials were analyzed by techniques, such as XRD, Raman shift, SEM and UV-vis diffuse reflectance spectra (DRS). The photocatalytic properties of the materials were investigated by the decomposition of the methylene blue (MB) dye solution under ultraviolet light. The results show that the size of Cu-ZnO nanorods was reduced when the Cu2+ doping ratio increased from 2 mol.% to 7 mol.%. The decomposition efficiency of the MB dye solution reached 92% - 97%, corresponding to the Cu2+ doping ratio changed from 2 - 7 mol.% (after 40 minutes of ultraviolet irradiation). The highest efficiency for the decomposition of the MB solution was obtained at a Cu2+ doping ratio of 2 mol.%.

基于含铬革屑制备吸附-降解型胶原/ZnO复合材料

危险废弃物含铬革屑的资源化利用是制革行业面临的一大难题.含铬革屑的主要成分胶原可作为吸附材料,但存在稳定性差、需解吸等问题,限制了其在水处理领域的应用.本文通过酸法从含铬革屑中提取胶原纤维并原位负载纳米氧化锌(ZnO)制备了吸附-降解型胶原/ZnO复合材料.红外光谱及X射线衍射谱图显示,ZnO成功负载且呈片状,具有六角纤锌矿晶型,负载到胶原纤维上后并不会影响其自身的光响应范围,禁带宽度为3.20eV.当锌前驱体溶液浓度为0.12mol/L、胶原纤维分散液pH值为8、胶原海绵质量为60mg时,复合材料光催化性能最佳;在160min内对10mg/L亚甲基蓝(MB)的降解率达95.2%;循环5次后,降解率依然可达到87.5%.动力学模型拟合结果显示,复合材料对MB的吸附更符合拟二级吸附动力学模型,受化学吸附控制;MB的光催化降解过程符合一级降解动力学方程,降解速率最高为0.0172min^(-1).此外,ZnO的引入提高了复合材料的抗菌性和热稳定性.

花球状ZnO的化学合成及光催化降解有机染料性能

用化学沉淀法制备一种花球状ZnO结构(ZnO-F),并通过扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征样品结构,用X射线粉末衍射(XRD)、X射线光电子能谱(XPS)和能量散射谱(EDS)分析样品成分,用紫外可见漫反射光谱(DRS)和荧光光谱(PL)分析样品的光电性能,通过光催化降解亚甲基蓝(MB)研究ZnO-F的光催化活性.结果表明:所得产物是直径约为1μm的ZnO,其花球结构由约为17 nm的纳米片交叉组装而成;样品具有较高的光催化活性,240 min内光催化降解MB的效率超过90%.

ZnO/CdS光电极的制备及降解亚甲基蓝研究

采用水浴法和SILAR法制备了ZnO/CdS光电极薄膜,并对其在光电催化降解污染物方面的性能进行了分析。结果表明,ZnO/CdS光电极具有优异的光电催化性能,在可见光照射下能够高效降解亚甲基蓝。其光电流密度最高为6.2 mA/cm^(2),同时其对亚甲基蓝的降解率也达到了97%。这归因于负载CdS后,可拓宽体系的光响应范围;且ZnO和CdS之间的异质结界面,促进了光生载流子的分离,提高了光电催化效率。

Ag^+/ZnO纳米晶的制备及对亚甲基蓝的异相光催化行为

以水合碳酸锌为前驱体利用激光复合加热蒸发技术制得平均粒径在20nm左右的Ag+掺杂ZnO纳米晶半导体光催化剂系列.用XRD、UV-Vis、TEM、PL等手段对纳米晶进行了表征,结果表明掺杂Ag+有助于ZnO对可见光的吸收,ZnO纳米晶为四针形,而掺杂产物为球形.在悬浮Ag+掺杂ZnO纳米晶的悬浮水相体系中,通过脱色率、紫外-可见吸收光谱和COD值的测定证实了Ag+掺杂有效的改善了ZnO对亚甲基蓝(MB)的光催化降解性能.探讨了几种因素对MB降解率的影响,当pH为12.0、C0为30mg·L-1、催化剂为2.5mg·L-1时,30min其脱色率达98.98%,COD的去除率达85.10%.

薄片状C_(60)/ZnO纳米复合材料的制备及其光催化性能

首先通过简单沉淀法制备了薄片状纳米ZnO,再利用化学吸附作用将C60与ZnO复合得到C60/ZnO纳米复合材料。采用XRD、SEM、XPS、Ra-man、DRS、PL等技术对样品进行表征,紫外光下以亚甲基蓝(MB)作为探针分子,研究C60/ZnO纳米复合材料的光催化活性。结果表明,C60/ZnO纳米复合材料的光催化活性优于单纯的纳米ZnO,且1%(质量分数)C60/ZnO的光催化活性最高,这是由于C60具有良好的接受和传导电子的作用,抑制了光生电子和空穴的复合,从而提高了光催化效率。

ZnO-TiO_2纳米纤维的制备及亚甲基蓝的太阳光催化降解

以钛酸四丁酯〔Ti(OC4H9)4〕、硝酸锌和聚乙烯吡咯烷酮(PVP)为原料,采用溶胶-凝胶法和静电纺丝法制备无机有机复合的PVP/ZnO-TiO2纤维,高温焙烧制得直径100～200 nm的ZnO-TiO2纳米纤维。通过差动-热重(DSC-TGA)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)等进行了表征,并测定了其对亚甲基蓝溶液的太阳光催化性能。结果表明,w(ZnO)=3%时,ZnO-TiO2纳米纤维对亚甲基蓝催化活性最高,太阳光照射6 h后降解率达99.4%,重复使用8次降解率仍然在95%以上。

可见光响应Fe掺杂ZnO/凹凸棒石复合材料的制备和光催化性能

采用直接沉淀法制备了Fe掺杂ZnO/凹凸棒石(Fe-ZnO/ATP)复合材料,评价了其在可见光条件下(>400 nm)光催化降解高浓度亚甲基蓝(MB)溶液的性能,并系统研究了ZnO负载量、Fe掺杂量和焙烧温度等对复合材料吸附性能和光催化性能的影响。结果表明,ATP的复合增强了复合材料对MB的吸附能力,MB在最佳条件下制备的Fe(0.3%)-ZnO(50%)/ATP复合材料上降解的表观反应速率常数(k_(app))为4.2×10^(-3)min^(-1),反应3.5 h后的降解率可达65.40%,与ZnO相比较,kapp和MB的降解率提高了2.6倍。XRD、TEM和UV-Vis-DRS的结果表明,复合材料中ATP的结构在热处理过程中基本保持不变,复合材料中Zn O的粒径明显减小,暴露了更多的活性位点。另外,Fe的掺杂可明显增强复合光催化剂对可见光的吸收,增强了对光的利用效率,从而使复合材料显示出优异的光催化活性。

Er^(3+):Y_3Al_5O_(12)/ZnO复合物的制备及其光催化性能的研究

通过溶胶凝胶、水热法合成了上转换发光剂Er^(3+):Y_3Al_5O_(12)掺杂的ZnO复合物可见光催化剂,采用X射线衍射仪(XRD)和扫描电镜(SEM)进行表征.以甲基橙染料为研究对象,研究了Er^(3+):Y_3Al_5O_(12)/ZnO复合物在可见光照射的光催化活性.此外,还研究了焙烧温度、焙烧时间、可见光照射时间和强度、染料溶液初始浓度和催化剂的用量对甲基橙染料降解率的影响.结果表明,加入上转换发光剂Er^(3+):Y_3Al_5O_(12)有效提高了降解率,且催化剂的用量为1.00g/L时降解效果最好.

WO_3-ZnO复合膜光催化降解亚甲基蓝的研究

采用溶胶-凝胶法制备WO3-ZnO复合膜,并用其对亚甲基蓝进行光降解,研究了复合膜的焙烧时间、光源、pH、溶液初始浓度及光照时间对亚甲基蓝降解率的影响。结果表明,在35 mL pH 12.47、浓度为5 mg/L的亚甲基蓝溶液中放置焙烧2.0 h的WO3-ZnO复合膜,紫外光光照60 min后亚甲基蓝的降解率可达98.1%。

Fe_2O_3/ZnO纳米复合结构的制备及其光催化性能研究

通过阳极氧化法在纯铁片基底上生长Fe_2O_3纳米管阵列薄膜,然后采用水热法在Fe_2O_3纳米管阵列薄膜上负载ZnO纳米棒,制得Fe_2O_3/ZnO复合纳米结构。借助FE-SEM、XRD、TEM、UV-Vis等手段,对不同反应时间下制得的Fe_2O_3/ZnO复合材料的形貌、结构、物相组成及光催化性能进行表征,重点考察了复合结构的亚甲基蓝可见光降解能力。结果表明,在外加电压为55V的条件下阳极氧化450s,所制备的Fe_2O_3纳米管阵列具有高度有序、分布均匀及垂直取向的结构特点,管径约为80nm;在90℃的碱性锌酸盐溶液中,水热反应1.5h后,制得的Fe_2O_3/ZnO复合材料具有最佳的光催化性能,该样品对亚甲基蓝的降解率可达85%。

环境友好型塑料用改性ZnO添加剂的光催化性能研究

以纳米ZnO和AgNO3溶液为原料,采用掺杂的方法制备了改性的塑料用ZnO添加剂,通过其光催化降解亚甲基蓝的效果评价了样品的光催化性能。实验结果表明,当银的掺杂量为2.8%,光催化剂添加浓度是0.8g/L时,此时Ag/ZnO复合粉体对亚甲基蓝的光催化降解效果最好。制备的Ag/ZnO复合粉体在紫外光区和可见光区都有较强的吸收,且吸收峰波长和Ag与纳米ZnO相比都出现了一定程度的红移。

超声协同纳米ZnO光催化降解亚甲基蓝研究

制备了光催化剂纳米ZnO,并对催化剂进行表征,探讨了超声协同纳米ZnO光催化氧化降解亚甲基蓝的影响因素.结果表明:与单一超声法(US)、单一光催化氧化法(UV+ZnO+O2)相比,超声协同光催化氧化法(US+UV+ZnO+O2)对亚甲基蓝的降解效果显著;在超声功率为200 W、催化剂用量为2.0g/L、亚甲基蓝溶液的初始浓度为10mg/L、光照时间100min时,亚甲基蓝溶液的降解率可达92%以上.

Visible light-responsive carbon-decorated p-type semiconductor CaFe_2O_4 nanorod photocatalyst for efficient remediation of organic pollutants

We report the fabrication and photocatalytic property of a composite of C/CaFe2O4nanorods(NRs)in an effort to reveal the influence of carbon modification.It is demonstrated that the photocatalytic degradation activity is dependent on the mass ratio of C to CaFe2O4.The optimal carbon content is determined to be58wt%to yield a methylene blue(MB)degradation rate of0.0058min.1,which is4.8times higher than that of the pristine CaFe2O4NRs.The decoration of carbon on the surface of CaFe2O4NRs improves its adsorption capacity of the MB dye,which is specifically adsorbed on the surface as a monolayer according to the adsorption isotherm analysis.The trapping experiments of the reactive species indicate that superoxide radicals(.O2)are the main active species responsible for the removal of MB under visible‐light irradiation.Overall,the unique feature of carbon coating enables the efficient separation and transfer of photogenerated electrons and holes,strengthens the adsorption capacity of MB,and improves the light harvesting capability,hence enhancing the overall photocatalytic degradation of MB.

锆掺杂纳米ZnO粉体的制备及其光催化性能

以Na2CO3、ZnSO4和ZrOCl2·8H2O为原料,采用直接沉淀法制备了纯ZnO和掺锆ZnO的纳米粉体,并用XRD、FT-IR、UV-Vis、SEM和TEM等表征手段进行表征,用紫外灯作为光源,亚甲基蓝溶液为光催化反应模型降解物,研究了ZnO和掺锆ZnO纳米粉体的光催化性能,并考察了前驱体煅烧温度与时间、掺锆量以及催化剂加入量等因素对降解率的影响,结果表明,煅烧温度为700℃时,相比纯ZnO掺杂锆的ZnO晶粒结晶良好,样品粒度分布更均匀,粒径变小,且掺锆的ZnO光催化活性高。当掺锆量为1%（摩尔比）时,光催化性能最好,加入催化剂量为0.8g.dm^-3,光降解时间为1h时,对亚甲基蓝溶液的降解率可达到98.65%。

ZnS/ZnO/rGO复合材料的制备及其光催化性能研究

以醋酸锌、硫化钠为原料,聚乙烯吡咯烷酮(PVP)为改性剂,采用一步合成法制备了β-ZnS,再通过焙烧制备ZnS/ZnO异质结材料,然后加入一定量氧化石墨烯(GO)利用水热法成功制备了ZnS/ZnO/rGO复合材料。结果表明,在水热时间16 h、水热温度140℃、GO∶(ZnS/ZnO)质量比20%的条件下,所制备的ZnS/ZnO/rGO复合材料在可见光光照120 min内对亚甲基蓝的降解率可达80.3%。

水热法制备的Ce-ZnO结构表征及其光催化性能研究

采用水热法制备不同摩尔比的稀土元素Ce掺杂Zn O光催化纳米材料Ce-Zn O,用红外(FTIR)光谱、X射线衍射(XRD)、紫外-可见光谱(UV-Vis)、光致发光(PL)等对其进行表征;研究了不同Ce掺杂量的Ce-Zn O对亚甲基蓝溶液(MB)光催化性能的影响。结果表明,Ce掺杂量2%时,Zn O的表面状态得到明显改善,生成更多的羟基自由基;同时增加光生电子空穴对的浓度,显著提高Zn O的光催化性能;经过2 h紫外汞灯照射,其降解率达到93.68%;且经过5次循环使用后,2%Ce-Zn O的降解率依旧能达到85%以上,具有良好的光催化性能和循环稳定性。

纳米ZnO阵列形貌对其光催化降解性能的影响

利用溶液法在不同形貌基片上制备了ZnO纳米棒阵列。通过聚苯乙烯球自组装阵列控制模板基片的形貌,制备出具有周期性结构的ZnO纳米花点阵;进而通过反应离子刻蚀聚苯乙烯球模板,实现了ZnO周期性点阵由纳米花向纳米环的结构转变。以亚甲基蓝水溶液为目标降解物,比较了不同ZnO纳米棒阵列的光降解能力,发现单位基片面积上ZnO纳米棒的有效受光面积是影响ZnO纳米棒阵列光降解能力的重要因素。