分子筛负载硫化镉光催化降解罗丹明B的研究

采用湿化学法制备了分子筛多孔二氧化硅负载硫化镉光催化材料CdS-SiO2,用于可见光降解有机污染物罗丹明B。结果表明,相比单相的硫化镉,分子筛负载的硫化镉表现出更高的光催化效率,且光降解后催化剂沉淀回收后仍可表现出较高的光催化降解能力。     

凹凸棒土负载氧化锌-二氧化钛的制备与性能

以凹凸棒土(ATP)作载体,硫酸氧钛、硫酸锌及碳酸铵为原料,采用化学沉淀法制备凹凸棒土负载氧化锌-二氧化钛(ATP/ZnO-TiO₂)纳米复合材料,并用XRD,TEM测试手段对样品进行了表征。以其对活性大红(BES)的降解效果作为评价其光催化性能的标准,对制备条件进行了优化。结果表明：ATP与二氧化钛的质量比为20%、二氧化钛与氧化锌的物质的量比为10∶1、煅烧温度为450 ℃下制备的复合材料光催化降解活性大红的效果最佳;与凹凸棒土负载二氧化钛（ATP/TiO₂）及凹凸棒土负载氧化锌（ATP/ZnO）相比,复合材料具有良好的可见光光催化性能。     

膨胀石墨／二氧化钛复合材料的制备与性能研究

本文主要研究了膨胀石墨／二氧化钛复合材料的制备,采用直接膨化的膨胀石墨与钛酸丁酯的醇溶液混合法制备膨胀石墨／二氧化钛复合材料,并分析了膨胀石墨／二氧化钛复合材料的物理性能,以甲基橙溶液的光催化降解反应为探针反应,评价了该复合材料的催化性能。     

溶剂热法制备N-S共掺杂TiO_2/MWCNT复合材料及其光催化活性的研究

采用溶剂热法,以四氯化钛为前驱体,以硫脲为氮源和硫源,将纳米二氧化钛负载在多壁碳纳米管的表面,制备氮、硫共掺杂的纳米二氧化钛/碳纳米管复合材料,以盐酸土霉素的光催化降解为探针反应,研究复合材料的光催化降解活性。结果表明,溶剂热法制备的纳米二氧化钛以锐钛矿相存在,均匀、致密的包覆在多壁碳纳米管的管壁上,添加硫脲的复合材料比未添加硫脲的样品在紫外和可见光区域均有较好的光吸收性能。硫脲的添加增强了复合材料的光催化活性,当二氧化钛和硫脲的摩尔比为1∶6时,催化剂的光催化活性最好,用过的样品经洗涤、烘干再生后用于实验,仍具有较好的光催化活性。     

天然矿物负载纳米二氧化钛复合材料的制备与表征

采用水解沉淀法制备了白炭黑、硅藻土和蛋白土负载纳米二氧化钛复合材料。通过SEM和XRD等手段对复合材料分别进行了表征,并用罗丹明B溶液的光催化脱色率来评价复合材料的光催化性能。结果表明,在复合材料表面负载了大量的二氧化钛且主要以锐钛型为主,白炭黑、硅藻土、蛋白土复合材料表面负载的二氧化钛的平均粒径分别为14.6、25.7、22.9 nm。二氧化钛/白炭黑、二氧化钛/硅藻土、二氧化钛/蛋白土3种复合材料的最佳制备条件分别为：700 ℃煅烧2 h,二氧化钛负载量为30%;700 ℃煅烧2 h,二氧化钛负载量为20%;600 ℃煅烧2 h,二氧化钛负载量为20%。3种复合材料对罗丹明B溶液15 min的降解率分别达到98.6%、97.4%和87.7%。     

多形貌二氧化钛/石墨烯复合材料的制备及光催化性能研究

为改善二氧化钛纳米材料在光催化降解废水有机物方面存在光生载流子复合率快等问题,基于石墨烯超高的电子迁移率,可控制备了二氧化钛/石墨烯复合材料,探究了二氧化钛形貌、石墨烯的掺杂对光催化性能的影响以及石墨烯的加入对二氧化钛形貌结构的影响。结果表明,石墨烯的掺杂提高了复合材料的吸附性能,花状二氧化钛/石墨烯、棒状二氧化钛/石墨烯表现出良好的光催化性能。     

FePc-TiO_2/CS复合材料制备及光催化降解染料废水

二氧化钛(TiO_2)具有化学稳定性好和光催化活性高等优点,广泛应用于光催化降解反应中,但其对可见光利用率较低。利用酞菁铁(FePc)在可见光区具有强吸收的特点提升TiO_2在可见光下的光催化性能。采用冷冻干燥法制备酞菁铁-二氧化钛/壳聚糖(FePc-TiO_2/CS)复合材料,并对其表面形貌、晶型结构以及热失重行为进行表征,同时将其作为光降解催化剂进行酸性橙7溶液的降解。结果表明,采用冷冻干燥法制备的FePc-TiO_2/CS复合材料具有多孔结构,在100~200℃温度范围内,FePc分解导致复合材料的热失重曲线有明显的失重峰。FePc-TiO_2/CS复合材料具有较高的光催化降解率,在30 min内对酸性橙7溶液的降解率达到90%以上。复合材料同时具有较好的稳定性,在重复使用3次后,对酸性橙7仍然保持较高的光催化活性。     

大孔炭负载二氧化钦复合催化剂降解甲基橙性能研究

制备了大孔炭负载二氧化钛光催化复合材料,在紫外光下降解甲基橙做其光催化性能评价.在相同条件下与P25光催化降解甲基橙相比较,TiO2 /C的催化降解活性显著高于P25,并考察了复合催化剂的用量及循环使用次数.实验结果表明,TiO2/C复合材料光催化降解甲基橙是吸附与光催化降解的协同作用的结果,具有良好的催化降解活性.     

银掺杂二氧化钛/活性炭复合材料的制备及其光催化性能研究

为提高二氧化钛/活性炭（AC）复合材料对可见光的利用率,基于溶胶-凝胶法制备了银掺杂的二氧化钛/活性炭复合光催化剂。利用一系列测试方法对光催化剂进行了表征,通过亚甲基蓝（MB）和Cr（Ⅵ）废水的降解效果研究了其光催化活性。结果表明,掺杂银的材料,吸附性能和可见光下的光催化性能均得到提升。在材料投加量为400 mg/L情况下,银-二氧化钛/AC复合光催化剂在30 min内对10 mg/L MB溶液的降解率达到98.55%,在60 min内对20 mg/L MB溶液、10 mg/L Cr（Ⅵ）溶液的降解率分别达到76.92%和53.90%;与未掺杂的材料相比,降解率分别提升了14%、47%、137%。这是由于Ag纳米颗粒可以有效地俘获价带电子,减少电子空穴的复合,从而提高了光催化效果。     

还原石墨烯/硫化镉纳米棒复合材料制备及其光催化性能

为调控硫化镉尺寸和形貌,采用水热法合成了还原型氧化石墨烯/硫化镉纳米棒(RGO/Cd S)复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅里叶变换红外光谱(FT-IR)等方法对产物进行了表征。通过调节硫化镉颗粒成核和生长速度,在乙二胺溶剂中水热合成了结构规整的硫化镉纳米棒及与石墨烯的复合材料。紫外分析表明,RGO/Cd S禁带宽度为2.81 e V。光催化降解实验表明,RGO/Cd S对甲基橙具有良好的光催化降解作用,当甲基橙溶液质量浓度为20 mg/L、RGO/Cd S用量为0.2%(质量分数)时,在可见光下反应480 min,甲基橙降解率可达96.3%。RGO/Cd S在光催化氧化处理废水领域具有潜在的应用价值。     

二氧化钛-钒酸铋复合材料光催化降解布洛芬的研究

为综合二氧化钛、钒酸铋光催化剂的性能,制备了二氧化钛-钒酸铋复合光催化剂,并以布洛芬为目标降解物,与二氧化钛、钒酸铋光催化剂的光催化性能进行了对比。以钛酸丁酯为原料,加入无水乙醇、盐酸、去离子水,采用凝胶法制备了二氧化钛光催化剂;以五水硝酸铋、偏钒酸铵为原料,加入浓硝酸、氢氧化钠,制备了钒酸铋、二氧化钛-钒酸铋复合光催化剂。此制备方法简便、高效。在可见光照射下,使用二氧化钛、钒酸铋、二氧化钛-钒酸铋3种光催化剂对布洛芬进行光催化降解,并将3种光催化剂分别联合过氧化氢对布洛芬进行光催化降解,考察了3种光催化剂的光催化性能。结果表明,未加入过氧化氢条件下,3种光催化剂的光催化性能由大到小的顺序为二氧化钛-钒酸铋、二氧化钛、钒酸铋;加入电子捕获剂过氧化氢后,提高了光催化剂降解布洛芬的效率,减少了电子-空穴对的复合速度,并且3种光催化剂的光催化性能由大到小的顺序为二氧化钛-钒酸铋、钒酸铋、二氧化钛。     

A high H2 evolution rate under visible light of a CdS/TiO2@NiS catalyst due to a directional electron transfer between the phases

The photocatalytic activity of CdS can be greatly improved by co-modification of NiS and TiO_2 materials; furthermore the order of connection affects much. A directional electron transfer route via CdS → TiO_2→ NiS is found crucial to the enhancement of ternary catalyst, where TiO_2 acts as an electron reservoir and Ni S works as an effective cocatalyst. Cd S/TiO_2@Ni S with Ni S loaded on TiO_2 has an activity of H_2 evolution 2.5 times higher than NiS@Cd S/TiO_2 with Ni S pre-loaded on Cd S. Faster e-/h+separation rates is obtained of Cd S/TiO_2@Ni S under visible light than under extra UV light irradiation, which in turn demonstrates the importance of directional electron transfer route.     

Photocatalytic oxidation of nitrogen oxide over titania–zeolite composite catalyst to remove nitrogen oxides in the atmosphere

The photooxidation of NO with oxygen over Hycom TiO₂ and zeolite (A and Y form zeolite: TiO₂-AZ and TiO₂-YZ) composite catalysts was studied to remove NO_x in the atmosphere. The photocatalytic oxidation activity of the titania in the composite catalyst in a proportion of AZ:TiO₂=3:7 is about three times larger than that in the bare titania. The adsorption behaviors of NO and NO₂ for the bare titania sample obey Langmuir adsorption equations of NO and NO₂, respectively. In the titania–zeolite composite catalysts, the adsorption data indicate the increase in the amount of NO adsorption on the TiO₂ phase and the decrease in the amount of NO₂ adsorption, compared with the bare titania. The acceleration of NO photooxidation rate, resulting from the increase in the amount of NO adsorbed and the decrease in the amount of NO₂ adsorbed, thus occurs on the TiO₂ phase. IR spectra, when irradiating the catalysts with UV, showed the immediate formation of nitrate and NO₂ species on the catalyst. The results lead to the conclusion that the zeolites promote the photocatalytic oxidation of NO over the titania.     

Photo-catalytic production of hydrogen form ethanol over M/TiO2 catalysts (M = Pd, Pt or Rh)

The photo-catalytic production of hydrogen from liquid ethanol, a renewable bio-fuel, over Rh/TiO₂, Pd/TiO₂ and Pt/TiO₂, anatase, has been studied. In the absence of the metal, TiO₂ shows negligible production of molecular hydrogen. The addition of Pd or Pt dramatically increases the production of hydrogen and a quantum yield of about 10% is reached at 350 K. On the contrary, the Rh doped TiO₂ is far less active. The low activity of Rh compared to that of Pd and Pt is not due to poor dispersion or low available Rh sites on the surface, as analyzed by XPS and TEM. For all three catalysts, TEM shows most particles with a size less than 10 nm. XPS results show that while the state of Pd and Pt particles in the as-prepared catalysts was mostly metallic that of the Rh was composed of non-negligible contribution of Rh cations. The extent of reaction of a series of alcohols was also studied, for comparison, on Pt/TiO₂. It was found that the reaction is governed by the solvation of the alcohol. In that regard, the production of molecular hydrogen over Pt/TiO₂ showed the following trend: methanol ≈ ethanol > propanol ≈ isopropanol > n-butanol.     

Hydrogen evolution by water splitting using novel composite zeolite-based photocatalyst

Novel zeolite-based material showing photocatalytic properties in the visible light have been synthesized by incorporating TiO₂, heteropolyacid (HPA) and transition metal, namely cobalt. This material shows high efficiency for water splitting under visible light irradiation. Hydrogen generation to the tune of 2171 μmol/h/g of TiO₂ has been achieved for the composite photocatalyst synthesized as compared to H₂ evolution rate to the tune of 131.6 μmol/h/g of TiO₂ for Degussa P25. This suggests that the TiO₂ which gets effectively dispersed and stabilized on the surface of zeolite works synergistically with cobalt and heteropolyacid to make the material active in visible light for evolution of hydrogen from water. TiO₂ is the photocatalyst, HPA functions as the dye sensitiser as well as redox system; zeolite functions as support matrix and as electron acceptor in synergy with cobalt. The probable mechanism for improved hydrogen evolution rate using such composite photocatalyst has been discussed.     

Photocatalytic activity of TiO2/ZSM-5 composites in the presence of SO4 ion

TiO₂/ZSM-5 composites were prepared from SiO₂ of rice husk ash and TiO₂ sol from hydrolyzed TiOSO₄ salt. The combined effect of these two materials greatly enhanced the photocatalytic decolorization of methylene blue dye solution. The instant decolorization of the dye solution in the dark by the composite, TiO₂/ZSM-5 (wt ratio 1:1), resulted from the combination of the adsorption by ZSM-5 zeolite and TiO₂ nano-particles, and of Na₂SO₄ salt adhering to the composite surface. As a strong flocculating agent, the SO₄²⁻ ion caused the precipitation of the dye onto the composite surface which consequently enhanced the photocatalytic decolorization of the dye under UV irradiation. The composite, TiO₂/ZSM-5 (wt ratio 1:5), completely decolorized the methylene blue dye in 2.5 h, giving an equivalent performance to that of TiO₂, P-25 powder.     

Photocatalytic degradation of omethoate using NaY zeolite-supported TiO2

The degradation of omethoate was conducted using H₂O₂ as oxidant, TiO₂ supported on NaY zeolite as photocatalyst and a 300 W lamp as light source. The effect of the calcination temperature of the photocatalyst, the amount of TiO₂ loaded on NaY zeolite, the photocatalyst amount, the pH value and the radiation time on the degradation ratio of omethoate were investigated. The results show that TiO₂/NaY zeolite photocatalyst prepared by sol-gel method had good photocatalysis. The photocatalytic optimum oxidation conditions of omethoate are as follows: the calcination temperature of the photocatalyst is 550°C,the amount of TiO₂ loaded on NaY zeolite is 35.2 wt-%, the amount of photocatalyst is 5 g/L, pH=8 and the radiation time is 180 min. Under these conditions, the removal ratio of omethoate is up to 93%.     

TiO2–g-C3N4/BMMS光催化氧化脱硫催化剂

为了提高TiO₂的光催化氧化脱硫(PODS)活性,利用负载和复合的协同作用,将TiO₂与g-C₃N₄复合,并负载于双介孔二氧化硅(BMMS)上,制备了TiO₂–g-C₃N₄/BMMS。以含二苯并噻吩(DBT)的十二烷溶液为模拟油,评价了催化剂的催化性能;优化了反应条件并提出了催化反应机理。结果表明:TiO₂–g-C₃N₄/BMMS具有明显的双介孔结构,TiO₂与g-C₃N₄已实现复合并负载于BMMS上,TiO₂–g-C₃N₄活性组分在载体上分散良好,与单一TiO₂相比对光的吸收能力增强,催化活性有明显提高,优化后的反应条件为,催化剂用量3%(质量分数),O/S摩尔比为10:1,萃取剂与模拟油体积比为1:1,此时脱硫率可达96.6%,且重复使用8次后脱硫率仍保持85%以上,PODS过程中的主要活性中间物种是·O₂^–和h⁺。     

活性炭纤维负载Pr3+:Y2SiO5/TiO2复合材料的制备与性能

为了提高纳米TiO₂对太阳光的利用率和实现光催化剂的回收再利用,采用溶胶-凝胶法将上转换荧光材料与纳米TiO₂复合,通过负载于活性炭纤维（ACF）表面制备了Pr³⁺：Y₂SiO₅/TiO₂/ACF复合材料。运用XRD、FT-IR、SEM、FS、UV-vis DRS等对材料的结构及性能进行了综合表征,并以亚甲基蓝为模拟污染物评价复合材料的可见光催化活性,考察了材料制备过程中煅烧温度、负载次数等制备条件对复合材料可见光下催化性能的影响。结果表明,在浸渍2次、800℃煅烧的制备条件下,复合材料中TiO₂为锐钛矿相（占34.1%）与金红石相（占65.9%）的混合相,亚甲基蓝（15 mg·L^-1）12 h内去除率高达93.8%,反应符合拟一级动力学,反应速率常数为0.2471 h^-1,回收再生利用4次后去除率仍保持在75%以上。     

TiO2-GO/LDHs复合光催化剂的制备和表征

将钛酸四丁酯与氧化石墨烯/镁铝层状双金属氢氧化物(GO/LDHs)通过水热合成原位生长法制备二氧化钛-氧化石墨烯/镁铝层状双金属氢氧化物(TiO2-GO/LDHs)复合光催化剂,对TiO2、TiO2-GO和TiO2-GO/LDHs的物相结构和表面形态进行表征。模拟太阳光条件下催化剂对有机染料罗丹明B和抗生素四环素的光催化降解效果。结果显示,GO的加入使TiO2颗粒分散的更加均匀,不易团聚。TiO2-GO对罗丹明B的降解效果优于单一TiO2,表明GO的加入扩展了TiO2的光响应范围,抑制了电子-空穴对的复合。TiO2-GO/LDHs的降解效果优于TiO2-GO,表明LDH捕获光生空穴,加速氧化反应,生成更多的强氧化性羟基,可以更好地降解污染物。