g-C_3N_4/TiO_2对亚甲基蓝光催化性能研究

采用偏钛酸为钛前驱体,三聚氰胺为氮源,制备g-C3N4/TiO2复合纳米光催化材料,研究不同原料配比、焙烧温度及不同焙烧时间制备的g-C3N4/TiO2光催化材料对亚甲基蓝以可见光激发降解亚甲基蓝溶液,考察其光催化活性,采用紫外-可见吸收(UV-Vis)光谱、三维荧光(FS)光谱进行机理研究。     

磁性MCM-41/CdS的制备及其可见光催化性能研究

采用两步沉淀法将CdS沉积在磁性MCM-41上,制备新型磁性MCM-41/CdS复合材料。通过X射线衍射光谱(XRD)、高分辨透射电镜(HRTEM)、紫外-可见吸收光谱(UV-Vis)、振动样品磁强计(VSM)等对其进行表征。以亚甲基蓝(methylene blue,简称MB)为模拟污染物,考察了磁性MCM-41/CdS复合材料的可见光催化性能。结果表明,CdS能有效地沉积在磁性MCM-41上,与CdS相比,该复合材料对MB的光催化降解效率明显提高,且可通过外加磁场进行分离。     

水热法制备α-FeOOH/MoS2纳米片复合物及其光催化性能

采用水热法成功制备了棒状α-FeOOH/MoS_2纳米片复合催化剂。运用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射光谱(UV-Vis)和荧光发射光谱(PL)对复合催化剂的结构和形貌进行了表征。结果表明:成功制备了长度为500nm左右的纳米棒状α-FeOOH,其与MoS_2纳米片形成良好的复合结构。以亚甲基蓝为模拟污染物,研究复合催化剂在可见光照射下的光催化特性。结果显示,棒状α-FeOOH/MoS_2纳米片复合催化剂在120min内对亚甲基蓝的降解率为98%,其降解动力学常数是纯α-FeOOH的3倍。根据活性基捕获实验结果,提出了α-FeOOH与MoS_2纳米片形成异质结的Z型光催化机理。     

高活性光催化剂纳米Ag-碳纳米管-混晶TiO_2复合纤维的可控制备

为解决TiO_2对太阳能有效利用率低、光生电子与空穴再复合率高、光催化活性低且难回收等应用难题,利用静电纺丝技术成功地制备了纳米Ag-碳纳米管(CNT)-混晶TiO_2复合纤维,并采用SEM、XRD、EDS及Raman等表征方法详细分析了材料的微观结构与组分,研究了纳米Ag-CNT-混晶TiO_2复合纤维对亚甲基蓝的光催化活性。结果表明:锐钛矿与金红石相TiO_2混晶不仅可降低材料的禁带宽度,还能减缓光生电子与空穴的复合淬灭;纳米Ag颗粒的局域表面等离激元共振可增强Ag-CNT-混晶TiO_2复合纤维的光吸收,CNT能促进光生电子与空穴的有效分离;纳米Ag-CNT-混晶TiO_2复合纤维对亚甲基蓝的首次降解率可达97.5%,且5次催化循环后对亚甲基蓝的降解率仍保持在90.0%以上。所得结论表明静电纺丝制备的新型纳米Ag-CNT-混晶TiO_2复合纤维是一种高活性的光催化剂,且容易回收,具有光降解亚甲基蓝的应用前景。     

铁掺杂二氧化钛光催化剂的性能研究

采用溶胶-凝胶法制备了铁掺杂二氧化钛粉体(Fe-TiO2),采用XRD、UV-Vis、PL、纳米粒度分析仪等方法对其进行表征和分析。结果表明,Fe掺杂降低了TiO2的相转变温度,拓展了TiO2对可见光的吸收范围,有效地抑制了光生电子-空穴对的复合。光催化降解亚甲基蓝(MB)的实验表明,Fe-TiO2粉体在普通日光灯下对亚甲基蓝的降解率达90.36%,明显优于德国Degussa公司生产的P25纯TiO2光催化剂对亚甲基蓝的降解率43.58%。     

钒-氮共掺杂TiO_2/凹凸棒复合光催化材料表征及光催化性能研究

用溶胶-凝胶法制备了钒-氮共掺杂TiO2/凹凸棒复合光催化材料,采用TEM、XRD、BET及UV-Vis漫反射吸收光谱对其性能进行了表征。在模拟太阳光条件下,以亚甲基蓝溶液为目标降解物,对复合光催化材料光催化性能进行评价,复合光催化材料投入到亚甲基蓝溶液中饱和吸附,在40mg/L的亚甲基蓝溶液中,复合光催化材料投加量为1g/L,在800W氙灯下反应6h后,对亚甲基蓝的降解率为84%;重复反应4次,光催化降解变化不大;静置40min后,完成沉降,实现回收。     

双元素共掺杂改性纳米TiO2的制备及光催化性能

以溶胶-凝胶法制备了钒氮双元素共掺杂的纳米TiO2,并对亚甲基蓝进行了降解处理。通过XRD、XPS、UV-Vis等方法对制备的样品进行了结构及性能的表征。结果表明:钒氮共掺杂能提高TiO2的光催化性能,掺杂后催化剂光响应范围发生了红移,可见光降解处理亚甲基蓝活性增强。     

纳米ZnO/Zn/CNT多孔复合结构的制备及其对亚甲基蓝的无光催化降解

以碳纳米管(CNTs)为基础材料,聚甲基丙烯酸甲酯(PMMA)为造孔剂,构筑多孔结构,并将水解反应所得的氧化锌/锌复合纳米颗粒附着在孔隙结构中,制得氧化锌/锌/碳纳米管多孔复合结构,氧化锌纳米棒直径约30~60nm,长径比可达40。对复合结构的微观结构及成分表征显示,制备ZnO/Zn/CNT多孔复合结构的过程中,无杂质生成,氧化锌晶体结构也没有发生变化。多孔复合结构对模拟污染物的暗室催化降解研究结果显示,复合结构催化降解亚甲基蓝时起主要作用的是ZnO纳米棒,在多孔结构中受力变形产生电子空穴对,在无光条件下降解有机污染物,且孔径越大、水流冲击力越强,对亚甲基蓝的催化降解效果越好。     

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。掺杂银显著提高了纳米ZnO的光催化性能     

SnO_2/聚氯乙烯复合材料的制备及光催化性能研究

以二氯化亚锡和聚氯乙烯(PVC)为主要原料,通过光化学合成的方法,在低功率紫外灯辐照下制备了复合光催化剂的前驱体,经热处理后得到了含有共轭聚合物结构的SnO2/聚氯乙烯复合光催化剂材料,并用XRD和UV-Vis等对复合材料进行了表征。光催化降解亚甲基蓝的实验表明,复合材料在可见光辐照下能有效地降解亚甲基蓝,复合材料的催化活性明显优于纯SnO2和PVC直接热处理产物。     

In situ controllable synthesis of Ag@AgCl core–shell nanoparticles on graphene oxide sheets

Graphene oxide-supported uniform Ag@AgCl core–shell nanoparticle composites have been successfully prepared by a facile two-step synthetic process. First, graphene oxide sheets were used as carriers to anchor and disperse Ag nanoparticles on their surface. Then these fixed Ag nanoparticles on carbon sheets are utilized as precursors, around which AgCl nanocrystals form in situ using FeCl₃ as oxidant, forming graphene oxide-supported Ag@AgCl core–shell nanoparticle composites. The composition of these attached Ag@AgCl core–shell nanoparticles can be easily controlled by adjusting the usage of FeCl₃, resulting in the formation of controllable core–shell nanostructures. Furthermore, these as-prepared graphene oxide–Ag@AgCl nanoparticle composites display effective photodegradation of methylene orange dye under visible light irradiation, which indicates their potential applications in environmental areas.     

A correlation story of syntheses of ZnO and their influence on photocatalysis

The crystallinity, surface morphology, porosity and band structure of semiconducting catalytic materials greatly influence their photocatalytic efficiency. Here, the semiconducting ZnOs were synthesized with three different synthetic routes of precipitation, solution combustion and direct calcination of precursor. All the synthesized catalysts were characterized thoroughly by X-ray diffraction, Field emission scanning electron microscopy, diffuse reflectance spectroscopy, Brunauer–Emmett–Teller surface area and photoluminescence. The synthesized catalysts show different nano-crystallinity, morphology, surface properties and band structure depending on the synthetic methods. All the synthesized catalysts were explored for photocatalytic degradation of methylene blue under visible and UV light illumination. The correlation between the physical properties and catalytic efficacy were established. The complete mechanism for the photocatalytic degradation of methylene blue was also proposed. The typical band structure and the longer life of excitons due to the presence of defects in solution combustion synthesized ZnO overpowered the other physical properties in influencing the visible and UV light assisted methylene blue degradation. This work shades light on the key controlling factors of a photocatalytic reactions and provides simple strategy for the development of efficient photocatalysts for solar energy conversion applications in solving energy crisis and environmental pollution problems.     

Photo-controlled redox of hydrogen-terminated silicon nanowire established by the reversible color alteration of methylene blue

The surface of hydrogen-terminated silicon nanowires was proved to be photo-active and redox-controllable under a visible light by the color alteration of methylene blue: colorless in dark and blue in light in the presence of H-SiNWs. The process of the redox reaction was monitored by a UV–vis spectrophotometry, showing a repeatable interconversion between methylene blue and lueco methylene blue within 2 h under conditions of alternant dark and light environments. During the redox process, oxygen was proved necessary for the reversible color alteration of methylene blue. The high repeatability in dark-reduction and photo-oxidation of methylene blue demonstrates the catalytic activity of ultrafine hydrogen-terminated silicon nanowires. Finally, a possible mechanism is deduced.     

CsTi2NbO7@N-TiO2杂化核壳结构的制备及其可见光催化性能

将CsTi₂NbO₇与异丙醇钛混合后与尿素在空气中煅烧制备出CsTi₂NbO₇@N-TiO₂核壳杂化材料,用XRD、SEM、TEM、UV-Vis DRS和XPS等手段对样品进行了表征。结果表明,N掺杂使TiO₂带隙变窄和吸收边红移,实现了可见光响应。杂化、核壳结构和N掺杂的协同作用不仅使CsTi₂NbO₇@N-TiO₂杂化核壳结构材料具有较强的可见光吸收特性,异质结面的存在还导致光生载流子分离和迁移效率增强,从而提高了可见光降解亚甲基蓝(MB)的光催化活性,其反应速率常数约为CsTi₂NbO₇的5.8倍。同时,这种材料还具有良好的光催化循环稳定性。     

核壳结构CdS/ZnS@rGA的制备及光催化性能研究

为研究纳米CdS/ZnS@rGA复合材料在可见光下的光催化性能,采用一步溶剂热法合成了以ZnS为壳的CdS/ZnS核壳纳米粒子,将CdS/ZnS核壳纳米粒子附着在rGO纳米片上,并组装成CdS/ZnS@rGA复合气凝胶,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等对样品进行了表征,通过亚甲基蓝(MB)的光催化降解实验表明：CdS/ZnS@rGA复合气凝胶的形成不仅可以提高CdS的光稳定性,还可以增强对MB吸附能力,同时对MB的降解有明显的促进作用。可见光反应90 min, 50 mg的CdS/ZnS@rGA对100 mL 20 mg/L MB的去除率最高达到99%。经过5次循环实验,该材料仍具有较好的可重复利用性。     

低对称性SiO2/Ag核壳复合纳米结构的银镜反应制备及表面增强拉曼散射活性研究

利用银镜反应在自组装的SiO2纳米粒子单层膜上制备了低对称性的SiO2/Ag核壳复合纳米结构.通过透射电镜(TEM)、扫描电镜(SEM)和紫外-可见分光光度计(UV-Vis)对核壳复合纳米结构的表面形貌和光学性质进行了表征.以亚甲基蓝作为探针分子,研究了低对称性SiO2/Ag核壳复合纳米结构的表面增强拉曼散射(SERS)活性.     

Synthesis and characterization of plasmonic visible active Ag/ZnO photocatalyst

Ag deposited ZnO nanoparticles (NPs) have been synthesized by simple sol–gel method for visible light active photocatalytic application. X-ray diffraction (XRD), TEM, UV–DRS and PL studies have been used to characterize the photocatalyst. The results show that Ag/ZnO NPs are wurtzite phase (WZ) of ZnO with Ag NPs in the surface region forming a hetero-interface of Ag–WZ (ZnO). Visible light activity of the material has been studied using photocatalytic degradation kinetics of methylene blue as a probe pollutant. Ag/ZnO NPs exhibit five times higher visible-light driven photocatalytic activity than pristine ZnO and four times than the reference Degussa P-25, under identical conditions. The high visible activity of Ag/ZnO may be attributed to the surface plasmon effect complemented sensitization in the presence of metallic Ag and effective charge separation through Ag–WZ hetero-interfaces.     

Substitutional nitrogen-doped tin oxide single crystalline submicrorod arrays: Vertical growth, band gap tuning and visible light-driven photocatalysis

High-density substitutional N-doped SnO₂ submicrorod arrays were grown on Si and quartz substrates by catalysts-free reactive sputtering. Scanning electron microscope and high-resolution transmission electron microscopy results show that the submicrorods are vertically aligned single crystal with quasi-tetrahedral pyramid shape nanotip at the top end. The density and the shape of the submicrorods can be modulated by the nitrogen partial pressure. Ellipsometry and optical absorption characterization show that after substitutional N-doping, the band gap of N-doped SnO₂ submicrorod shifts toward visible light region (up to 624 nm), and the visible light absorption are significantly enhanced due to the band gap narrowing. The photodegradation of methylene blue by N-doped SnO₂ submicrorod under visible light illumination is demonstrated, and it was found that the surface-to-volume ratio plays an important role in achieving high photocatalytic reactivity. The SnO₂:N submicrorod arrays with visible light band gap may have potential applications in solar cells electrode and visible light sensitive photocatalyst.     

Sol-gel synthesis of silver/titanium dioxide (Ag/TiO2) core-shell nanowires for photocatalytic applications

Silver/titanium dioxide (Ag/TiO₂) core-shell nanowires were synthesized by direct coating of TiO₂ shells on the surface of silver nanowires (AgNWs) through a simple sol-gel process. TEM image and EDX elemental analysis had confirmed the presence of TiO₂ coating on the surface of AgNWs. The thickness of titanium dioxide coating was about 10 nm. These Ag/TiO₂ core-shell nanowires showed good photocatalytic activities in the decomposition of methylene blue as a model organic dye in aqueous solution under UV light irradiation. Ag/TiO₂ core-shell nanowires are potentially useful in photocatalytic applications.     

ZnO/CNTs复合材料的制备、表征及光催化性能

采用水热法制备了一系列氧化锌和碳纳米管的复合材料(ZnO/CNTs),详细考察了碳纳米管的含量对复合材料光催化性能的影响。利用X射线衍射仪、紫外-可见漫反射吸收光谱、扫描电子显微镜、X射线能谱、透射电子显微镜、X射线光电子能谱和氮气吸附-脱附等测试手段对样品的结构、形貌和光学性质进行了表征,并用亚甲基蓝溶液模拟污染物,评价了ZnO/CNTs复合材料的光催化性能。结果表明:添加CNTs提高了ZnO的比表面积,增强了ZnO的可见光吸收。ZnO/CNTs复合材料较纯ZnO具有更高的光催化活性,并且随着CNTs含量的增加,ZnO/CNTs复合材料的光催化活性呈先增加后减小的趋势。当CNTs的含量为0.3%(质量分数)时,ZnO/CNTs复合材料的光催化活性最高,经过50 min光照后,亚甲基蓝的降解率达到了96.2%。