ZnS纳米球的水热法制备及其光催化性能研究

在表面活性剂十六烷基三甲基溴化铵(CTAB)的辅助下,以乙酸锌为锌源,硫脲(NH2)2CS为硫源,使用水热法通过改变反应时间,成功制备了不同粒径的ZnS球状颗粒。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X-射线能谱,高分辨透射电子显微镜(HRTEM))、紫外可见分光光谱和光致发光谱(PL)等测试手段对样品的晶体结构、形貌、光学性质进行了分析。通过对不同粒径的ZnS纳米颗粒对亚甲基蓝的光催化降解的催化活性进行了评估。实验结果表明:在表面活性剂CTAB的作用下,随着反应时间的增加,生成的ZnS晶核生长成纳米颗粒,然后ZnS纳米颗粒将进一步发生团聚从而形成平均粒径超过500nm的ZnS纳米球,但制备的ZnS产物的晶体结构均为立方纤锌矿结构。随着ZnS粒径的增加,样品的紫外吸收峰从418nm逐渐蓝移到362nm,而PL发射峰位的峰强随着粒径的增大而增强。光催化结果显示,反应12h制备的ZnS纳米球的光催化性能最佳。     

ZnS纳米球的水热法制备及其光催化性能研究

在表面活性剂十六烷基三甲基溴化铵(CTAB)的辅助下,以乙酸锌为锌源,硫脲(NH₂)₂CS为硫源,使用水热法通过改变反应时间,成功制备了不同粒径的ZnS球状颗粒.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱,高分辨透射电子显微镜(HRTEM))、紫外可见分光光谱和光致发光谱(PL)等测试手段对样品的晶体结构、形貌、光学性质进行了分析.通过对不同粒径的ZnS纳米颗粒对亚甲基蓝的光催化降解的催化活性进行了评估.实验结果表明:在表面活性剂CTAB的作用下,随着反应时间的增加,生成的ZnS晶核生长成纳米颗粒,然后ZnS纳米颗粒将进一步发生团聚从而形成平均粒径超过500nm的ZnS纳米球,但制备的ZnS产物的晶体结构均为立方纤锌矿结构.随着ZnS粒径的增加,样品的紫外吸收峰从418nm逐渐蓝移到362nm,而PL发射峰位的峰强随着粒径的增大而增强.光催化结果显示,反应12h制备的ZnS纳米球的光催化性能最佳.     

二苯胺磺酸钠还原法制备粒径可控的金纳米粒子

采用二苯胺磺酸钠还原四氯合金酸的方法,在室温条件下,用SDS(十二烷基硫酸钠)、SDBS(十二烷基苯磺酸钠)作表面活性剂,成功地合成了金纳米粒子.分别讨论了还原剂二苯胺磺酸钠、表面活性剂(SDS、SDBS)及四氯台金酸的浓度等对金纳米粒子的粒径和形貌的影响.通过控制反应条件,可以合成出平均粒径大约为10、14、30、36nm的金纳米粒子.利用透射电镜(TEN)、紫外-可见(UV-Vis)吸收光谱对金纳米粒子进行了表征.研究结果表明不同的SDS或SDBS/HAuCl4的摩尔比,对金纳米粒子的尺寸大小有影响.     

SDS-PVP水溶液中超细镍粉的制备

在十二烷基硫酸钠(SDS)-聚乙烯吡咯烷酮(PVP)混合水溶液中, 采用水合肼还原氯化镍制备超细镍粉. SEM结果表明, 该超细镍粉为球形, 表面呈现针状叠合的特殊形貌. XRD结果表明,该超细镍粉由平均粒径约为10 nm的面心立方结构(fcc)的原生纳米镍晶粒组成, 且主要沿(111)晶面生长. TEM清晰观察到原生纳米镍晶粒在PVP的空间桥联作用下自组装成超细镍粉的中间过程. SDS-PVP的组成对超细镍粉的粒径和表面形貌有显著影响, 在一定浓度范围内, 随着SDS或PVP浓度增大, 原生纳米镍晶粒和超细镍粉的平均粒径均呈减小趋势, 表明通过改变SDS-PVP组成可以调控超细镍粉的粒径和形貌.     

表面活性剂对导电聚吡咯性能的影响

采用十六烷基溴化铵（CTAB）、十二苯磺酸（DBSA）、十二烷基硫酸钠（SDS）3种表面活性刘为软模板,过硫酸铵为氧化剂,在0℃冰水浴条件下制备导电聚吡咯。通过改变表面活性剂的种类和用量,考察其对聚吡咯形貌和性能的影响。用FTIR、XRD、SEM等对聚吡咯材料进行表征。研究表明：表面活性剂和PPy存在一定程度上的相互协同作用,添加表面活性剂能够直接调整聚吡咯分子的形貌;掺杂DBSA、SDS可合成球状结构聚吡咯,掺杂CTAB可合成棒状结构的聚吡咯,并且当”（PPy）：n（CTAB）-5时,合成的聚吡咯导电性能最好。     

水热法合成AgGd0.9Eu0.1(WO4)2及其发光性能

利用水热法制备了不同形貌的AgGd_0.9Eu_0.1(WO₄)₂ 红色发光材料, 通过X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱分析(EDS)、透射电镜(TEM)及荧光光谱(PL)对不同条件下制备样品的物相、形貌和荧光性质进行了表征, 探讨了初始溶液的pH值和表面活性剂的种类对产物形貌和颗粒尺寸的影响. 结果表明: 本文所述条件下所得样品均属于单斜晶系|初始溶液的pH值和表面活性剂的种类对产物的形貌起关键作用. 通过调整初始溶液的pH值和表面活性剂的种类, 可以得到不同粒径的球形、棒状和空心球形颗粒|AgGd_0.9Eu_0.1(WO₄)₂的发射光谱表现为Eu^3＋离子的特征发射, 样品颗粒的形貌以及颗粒尺寸对发射光谱的强度有一定影响.     

球状、立方状及空心立方状PbS纳米晶的控制合成及其形成机理

以醋酸铅为铅源,硫代乙酰胺为硫源,在表面活性剂十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)共同作用下,通过简单地调节水热反应的反应温度控制合成出球状、立方状和空心立方状PbS纳米晶。利用XRD、TEM对合成产物的结构和形貌进行了表征,发现合成的球状、立方状和空心立方状PbS纳米晶尺寸均一,直径为100 nm左右。对球状、立方状和空心立方状PbS纳米晶的形成机理进行了初探,结果表明反应温度较低时,水热反应初始阶段形成的PbS小颗粒呈球形,在表面活性剂SDS的烷基链模板和CTAB微胶束软模板共同作用下生成球状PbS纳米晶;反应温度较高时,水热反应初始阶段形成的PbS小颗粒由于自身的立方相岩盐晶体结构的影响有呈立方状趋势,在SDS和CTAB共同作用下产物堆积成空心立方体状或立方状。     

介孔氧化镍的复合表面活性剂模版法制备及表征

用六水合硝酸镍为镍源,尿素为沉淀剂,以少量的复合表面活性剂(SDS/P123,CTAB/P123,CTBA/SDS)为模板水热制备了介孔氧化镍。分别采用热重-差示扫描量热(TG-DSC)、傅立叶红外光谱(FTIR)、X射线衍射(XRD)、氮气吸附脱附、扫描电子显微镜(SEM)、透射电子显微镜(TEM)对产物的结构和形貌进行了表征。用循环伏安法,恒电流充放电和交流阻抗谱等对材料进行了电化学性能的测试。结果表明,以复合表面活性剂SDS/P123为模板制备的介孔氧化镍有最大的比表面积、孔径和比电容,且当SDS/P123质量比为2:1时,所制备的氧化镍比表面积、孔径和比电容分别为209 m2.g-1,0.407 cm3.g-1,265 F.g-1。     

纳米铜粒子制备及二次稳定的研究

选用硫酸铜为原料,十六烷基三甲基溴化铵(CTAB)为稳定剂,以硼氢化钠为还原剂,采用液相还原法制备纳米铜颗粒。CTAB既是一种表面活性剂又是一种稳定剂。添加十二烷基苯磺酸钠(SDBS)对制备的纳米铜溶胶进行二次稳定。考察铜盐及稳定剂对所形成的铜纳米粒子的稳定性的影响。通过紫外-可见分光光度计、X射线衍射仪和透射电子显微镜等表征手段对纳米铜进行表征。结果显示,紫外吸收光谱在570nm处有纳米铜特征吸收峰,SDBS二次稳定后的纳米铜颗粒无论在形貌上还是分散性上都有所改善。XRD图谱通过Scherrer计算得出铜纳米粒子平均粒径为13nm,与透射图像分析吻合。     

表面活性剂对海藻酸钠稀水溶液剪切粘度的影响

通过粘度法考察了不同pH值时, 阴离子聚电解质海藻酸钠(NaAlg)与阴离子表面活性剂十二烷基硫酸钠(SDS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)、非离子表面活性剂辛基酚聚氧乙烯醚(TritonX-100)以及它们的复配体系的相互作用. 研究表明, 在酸性条件下, SDS和TritonX-100与NaAlg之间主要是疏水作用, 随着表面活性剂浓度的增加, 体系粘度下降直到基本不变, CTAB与NaAlg主要发生静电作用和疏水作用, 体系粘度随CTAB浓度的增加呈现先上升后下降的趋势. 在实验条件下, TritonX-100浓度为0.05 mmol·L-1时, SDS的加入, 使得NaAlg/TritonX-100体系的零剪切粘度下降, 而CTAB的加入, 在pH=3.0和5.0时, NaAlg/TritonX-100体系的零剪切粘度出现上升, 在pH=6.4时, 该体系零剪切粘度下降.     

可见光响应的Co3(PO4)2/Ag3PO4纳米复合光催化剂的制备及表征

采用简单的化学偏聚法合成出Ag3PO4纳米颗粒、磷酸钴(Co3(PO4)2,CoP)纳米片以及它们两者的纳米复合结构(CoP/Ag3PO4),同时还比较了它们的可见光催化活性.采用场发射扫描电镜(FESEM)、X射线衍射(XRD)、紫外-可见(UV-Vis)吸收光谱以及光致发光谱等手段对其形貌、结构、光学以及可见光催化性能等进行表征.结果表明,CoP/Ag3PO4复合纳米结构的可见光降解甲基橙(MO)的速率和循环稳定性均明显优于其它两种物质.这表明CoP应该起着共催化剂的作用,它能够抑制光生电子与空穴之间的复合,并且提供大量高活性的光生空穴.此外,我们还发现CoP/Ag3PO4降解另一种阳离子型染料——罗丹明B(RhB)的能力则远不如纯Ag3PO4,这可能是与光催化剂的表面性质发生改变有关,造成更低的RhB吸附能力.本文提供了一种廉价制备高效可见光催化剂的新方法.     

全有机S型异质结PDI-Ala/S-C3N4光催化剂增强光催化性能

Organic photocatalysts have attracted attention owing to their suitable redox band positions, low cost, high chemical stability, and good tunability of their framework and electronic structure. As a novel organic photocatalyst, PDI-Ala (N, N'-bis(propionic acid)-perylene-3, 4, 9, 10-tetracarboxylic diimide) has strong visible-light response, low valence band position, and strong oxidation ability. However, the low photogenerated charge transfer rate and high carrier recombination rate limit its application. Due to the aromatic heterocyclic structure of g-C₃N₄ and large delocalized π bond in the planar structure of PDI-Ala, g-C₃N₄ and PDI-Ala can be tightly combined through π–π interactions and N―C bond. The band structure of sulfur-doped g-C₃N₄ (S-C₃N₄) matched well with PDI-Ala than that with g-C₃N₄. The electron delocalization effect, internal electric field, and newly formed chemical bond jointly promote the separation and migration of photogenerated carriers between PDI-Ala and S-C₃N₄. To this end, a novel step-scheme (S-scheme) heterojunction photocatalyst comprising organic semiconductor PDI-Ala and S-C₃N₄ was prepared by an in situ self-assembly strategy. Meanwhile, PDI-Ala was self-assembled by transverse hydrogen bonding and longitudinal π–π stacking. The crystal structure, morphology, valency, optical properties, stability, and energy band structure of the PDI-Ala/S-C₃N₄ photocatalysts were systematically analyzed and studied by various characterization methods such as X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, ultraviolet visible diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, and Mott-Schottky curve. The work functions and interface coupling characteristics were determined using density functional theory. The photocatalytic activities of the synthesized photocatalyst for H₂O₂ production and the degradation of tetracycline (TC) and p-nitrophenol (PNP) under visible-light irradiation are discussed. The PDI-Ala/S-C₃N₄ S-scheme heterojunction with band matching and tight interface bonding accelerates the intermolecular electron transfer and broadens the visible-light response range of the heterojunction. In addition, in the processes of the PDI-Ala/S-C₃N₄ photocatalytic degradation reaction, a variety of active species (h⁺, ·O₂^-, and H₂O₂) were produced and accumulated. Therefore, the PDI-Ala/S-C₃N₄ heterojunction exhibited enhanced photocatalytic performance in the degradation of TC, PNP, and H₂O₂ production. Under visible-light irradiation, the optimum 30%PDI-Ala/S-C₃N₄ removed 90% of TC within 90 min. In addition, 30%PDI-Ala/S-C₃N₄ displayed the highest H₂O₂ evolution rate of 28.3 μmol·h^-1·g^-1, which was 2.9 and 1.6 times higher than those of PDI-Ala and S-C₃N₄, respectively. These results reveal that the all organic photocatalyst comprising PDI-based supramolecular and S-C₃N₄ can be efficiently applied for the degradation of organic pollutants and production of H₂O₂. This work not only provides a novel strategy for the design of all organic S-scheme heterojunctions but also provides a new insight and reference for understanding the structure–activity relationship of heterostructure catalysts with effective interface bonding.      

Zr改性MnO_x/MWCNTs催化剂的结构特征与低温SCR活性

以ZrO(NO3)2·2H2O为前驱体对多壁碳纳米管(MWCNTs)进行了改性并负载MnOx制备了MnOx/ZrO2/MWCNTs催化剂.考察了Zr对催化剂低温选择性催化还原(SCR)反应活性的影响,并通过多种分析手段对催化剂的结构进行了表征.结果表明Zr的添加对催化剂的低温SCR活性具有显著的促进作用,当Zr负载量为30%时,催化剂活性最佳.X射线衍射(XRD)、拉曼(Raman)光谱、透射电镜(TEM)、N2吸附-脱附的表征结果分析表明,适量的Zr改性促进了MnOx在载体表面的分散,增强金属氧化物与MWCNTs之间的作用,也能增加催化剂的比表面积、孔容和孔径.X射线光电子能谱(XPS)、H2程序升温还原(H2-TPR)和NH3程序升温脱附(NH3-TPD)的分析结果则显示,Zr能提高催化剂表面化学吸附氧浓度,促进Mn3+转化为Mn4+,从而使催化剂表面的活性位点增多,氧化还原能力增强,同时还提高了催化剂表面酸性位点的数量和强度,促进了NH3的吸附,是MnOx/ZrO2/MWCNTs催化剂低温SCR活性提高的主要原因.     

Synthesis and Visible-light Photocatalytic Performance of C-doped Nb2O5 with High Surface Area

C-doped Nb₂O₅ with abundant mesopores has been successfully synthesized through a facile solvothermal synthetic strategy followed by calcination treatment. The resulting C-doped Nb₂O₅ displayed the highest BET surface area(345 m²/g) and large mesopore size(ca. 4.2 nm), capable of offering more accessible active sites as well as faster mass transfer for catalysis. Besides, the doping of C(2.21%, molar fraction) at the O sites in Nb₂O₅ lattice greatly enhanced visible-light response by lowering the band gap, thereby making the material a photocatalyst under visible-light irradiation. Typically, the C-doped Nb₂O₅ exhibited a high H₂ evolution rate of ca. 39.10 μmol·g^-1·h^-1 and also degraded RhB dye completely after 30 min of visible light exposure, which turned out to be much better than Degussa P25 and pure Nb₂O₅ catalysts.     

Synthesis of Gd-N Codoped Porous TiO2 Photocatalyst and Its Enhanced Photocatalytic Activities

Visible-light-active Gd-N codoped porous TiO₂(Gd-N-TiO₂) photocatalyst was fabricated by an evapora-tion-induced self-assembly route using surfactants as structure-directed agents. As-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy(TEM), X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller(BET) method, and ultraviolet-visible absorption spectroscopy. The results indicated that synergistic reaction occurred when codoping with Gd³⁺ and N, which enhanced the light absorption properties of TiO₂. Irregular worm-like particles with wide interparticle spaces were clearly observed by TEM. The average particle size of Gd-N-TiO₂ decreased to ca. 8 nm because co-doping inhibited the particles growth significantly. Thus, the specific surface area of Gd-N-TiO₂(198.7 m²/g) was higher than that of Degussa P25 TiO₂(50 m²/g). Gd-N-TiO₂ exhibited a high photocatalytic activity toward methyl orange degradation under UV-Vis or visible-light irradiation. The Gd-N-TiO₂ catalyst also presented a stable performance without losing activity after four successive photocatalytic experiments. The facile synthesis and excellent activity of Gd-N-TiO₂ indicated its great potential as industrial catalysts for wastewater treatment.     

层状苯膦酸-磷酸锆的合成与磺化研究

研究了制备苯膦酸-磷酸锆Zr(PO₄H)_2-n(PO₃Ph)_n的主要影响因素。在F^-/Zr⁴⁺=12和H₃PO₄/Zr⁴⁺=20条件下,通过改变苯膦酸用量获得了n=0～2的系列单一晶相层状苯膦酸-磷酸锆,其热稳定性达400℃以上。苯膦酸-磷酸锆的磺化试验表明层间苯环可被完全磺化,磺化产物Zr(PO₄H)_2-n(PO₃PhSO₃H)_n具有丰富的酸性位,其热稳定性亦可达到300℃以上。     

Synthesis and study of Bi2Ti2O7/TiO2 composites as efficient visible-light-active photocatalysts in the reduction of aqueous Cr(VI)

In this work, Bi_2Ti_2O_7/TiO_2 composites were synthesized and studied as potential visible-light-activated photocatalysts in the reduction of aqueous Cr(VI). Bi_2Ti_2O_7/TiO_2 composites with tunable compositions were synthesized via a solvothermal-calcination two-step method, simply by changing the molar ratios of Bi(NO_3)_3·5H_2O to tetrabutyl titanate in the reactants. The compositions, structures and optical properties of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites were characterized by X-ray diffraction, field emission scanning electron microscopy and UV–vis diffuse reflectance spectra. The photocatalytic activity of the as-synthesized Bi_2Ti_2O_7/TiO_2 composites was tested in the reduction of aqueous Cr(VI)under visible-light(λ420 nm) irradiation, and compared with that of TiO_2 nanoparticles. It was observed that the as-synthesized Bi_2Ti_2O_7/TiO_2 composites exhibited much higher photocatalytic activity than TiO_2 nanoparticles, and the most efficient composite(300 mg) can achieve the complete reduction of Cr(VI) in 300 mL of 50 mg/L K_2Cr_2O_7 aqueous solution under visible-light(λ420 nm)irradiation in 90 min.     

P507萃取纯化V(Ⅳ)制备草酸氧钒及其物化性能

从钒渣钠化焙烧后的含钒浸液中, 采用2-乙基己基磷酸单-2-乙基己酯(P507)萃取-草酸反萃取-蒸发结晶新工艺制备了草酸氧钒, 优化了草酸反萃取工艺的条件. 研究结果表明, 采用2.0 mol/L草酸溶液, 在水相与有机相体积比V(A):V(O)为1:5时, 于50 ℃下经过三级(理论)反萃取, 钒的反萃取率可达到99.98%, 反萃取液中VOC₂O₄浓度可达290.0 g/L以上. 负载的反萃取液经膜过滤除去残留有机物后, 再经蒸发结晶得到草酸氧钒. 采用X射线衍射、 X射线能谱、 热场发射扫描电子显微镜及同步热分析等手段表征了草酸氧钒的物化性能, 结果表明, 草酸氧钒的结构为VOC₂O₄·2H₂O, 粒度分布均匀, 结晶度高.     

微波水热制备Fe-Zr催化剂及其CO加氢制烯烃性能研究

以ZrO（NO₃）₂·2H₂O和Fe（NO₃）₃·9H₂O为原料,采用微波水热法制备了不同Fe₂O₃/ZrO₂物质的量比的Fe-Zr催化剂,并经K改性,研究了其催化CO加氢一步法合成低碳烯烃性能。采用XRD、SEM、TEM和N₂吸附-脱附等手段对其物相、形貌和比表面积等进行了表征。结果表明,与共沉淀法相比,微波水热制备的Fe-Zr催化剂颗粒粒径均一,具有相对较小的比表面积和较大的孔径;在CO加氢反应中,Zr助剂的添加显著改善了产物分布,Fe、Zr间适宜的相互作用和相对较大的孔径,有利于抑制CH₄的生成,提高烯烃选择性。随着Fe₂O₃/ZrO₂物质的量比的降低,Fe、Zr间相互作用逐渐增强,烯烃选择性和收率先增加后降低。当Fe₂O₃/ZrO₂物质的量比为75：25时,在340 ℃、1.5 MPa、1 000 h^-1和H₂/CO物质的量比为2的条件下,烯烷比（O/P）达4.86,总烯烃收率达62.57 g/m³。     

Zr改性Ni2P/SBA-15催化剂的制备及其加氢脱氧性能

以正丙醇锆（n）和Zr（SO₄）₂（m）为锆源制备了Zr改性的Ni₂P/ZrO₂-SBA-15（n）和Ni₂P/ZrO₂-SBA-15（m）催化剂,并采用XRD、BET、CO吸附、XPS、NH₃程序升温脱附等手段对催化剂进行了表征。以苯并呋喃（BF）为模型化合物,研究了催化剂加氢脱氧（HDO）性能。结果表明,Zr改性后,形成了新的层状结构的ZrP;Zr的引入有助于生成更多、更小粒径的Ni₂P活性相,催化剂的酸强度和酸量均提高。与正丙醇锆相比,Zr（SO₄）₂为锆源能够获得比表面积大、酸性强、酸量大的催化剂,得到更多的ZrP相、更小粒径的Ni₂P晶粒,暴露更多的Ni活性位点。Ni₂P/ZrO₂-SBA-15（n）和Ni₂P/ZrO₂-SBA-15（m）的BF HDO产率分别为71.5%和85.9%,较Ni₂P/SBA-15分别提高了14.0%和28.4%。催化剂HDO活性、脱氧产物选择性和产率大小顺序为：Ni₂P/ZrO₂-SBA-15（m） > Ni₂P/ZrO₂-SBA-15（n） > Ni₂P/SBA-15。