功能化ZnxCd1-xS纳米晶的制备及其光学性能的研究

以氯化锌、氯化镉和硫化钠为原料，采用巯基乙醇为表面修饰剂，H₂O/DMF为溶剂，制得未团聚且分散均匀的纳米晶溶液，同时得到表面富含羟基基团不同锌镉组成的复合Zn_xCd_1-xS纳米晶。利用FTIR、EDS、UV-Vis、XRD、荧光光谱(PL)考察了复合纳米晶结构和光学性能的关系，并利用紫外灯摄像技术对Zn_xCd_1-xS纳米晶的光致发光性能进行     

Ag2S/Ag3PO4/Ni复合薄膜的制备及其光催化性能

采用电化学方法制备Ag₂S/Ag₃PO₄/Ni复合薄膜,以扫描电子显微镜（SEM）、X射线衍射（XRD）、紫外-可见漫反射光谱（UV-Vis DRS）对薄膜的表面形貌、晶相结构、光谱特性及能带结构进行了表征,以罗丹明B为模拟污染物对薄膜的光催化活性和稳定性进行了测定,采用向溶液中加入活性物种捕获剂的方法对薄膜的光催化机理进行了探索。结果表明：最佳工艺制备的Ag₂S/Ag₃PO₄/Ni是由均匀的球形纳米颗粒构成的薄膜,其光催化活性明显优于纯Ag₃PO₄/Ni薄膜和纯Ag₂S/Ni薄膜,且在保持薄膜光催化活性基本不变的前提下可循环使用6次。提出了可见光下Ag₂S/Ag₃PO₄/Ni复合薄膜光催化降解罗丹明B的反应机理。     

亚微米级Ag2S空心球的乳液法合成

Hollow Ag₂S spheres have been prepared via hydrolyze reaction of Ag₂S₂O₃， which formed from the reaction of AgNO₃ with Na₂S₂O₃， in cyclohexane/water/polyglycol emulsion system. It was found that the component of the reaction system has a significant influence on the formation of hollow Ag₂S spheres. The possible formation mech-anism of the hollow Ag₂S spheres in the emusion system was also discussed.     

室温下制备Cu7S4和Ag2S的球形空心纳米粒子

以Cu₂O和Ag₂O纳米粒子为前驱体,利用Kirkendall效应,在室温条件下制备出Cu₇S₄和Ag₂S的球形空心纳米粒子。用X-射线衍射(XRD)、透射电镜(TEM)、扫描电镜(SEM)等测试手段对产物进行了表征。结果表明,粒子的空心化程度取决于反应物的物质的量之比;空心粒子的形貌与前驱体粒子的形貌很相似。研究了这种反应的机理,并对这两种氧化物发生这类反应的难易程度作了理论探讨。     

微波水热两步法合成高可见光响应Ag2S/ZnO及其光催化性能、机理

在不同的制备条件下,通过微波水热两步法获得了一系列Ag₂S/ZnO光催化剂,采用X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、扫描电子显微镜(SEM)和N₂吸附-脱附等测试手段对产物结构和形貌进行了表征。结果表明,产物以六方纤锌矿ZnO为主,其晶型结构并未随着反应温度和Ag₂S物质的量的增加而改变。Ag₂S的引入显著增强了光催化剂在可见光区的吸收,使吸收边带发生红移,同时抑制了ZnO(001)晶面的生长。另外,所得产物的形貌随着Ag₂S物质的量的增加从爆米花状转变为少量的柱体颗粒,且BET比表面积经过复合后明显减小。以罗丹明B为目标降解物,研究并比较了一系列Ag₂S/ZnO光催化剂对罗丹明B的光降解性能。结果表明,n_Ag2S/n_ZnO=1:10时,光催化剂在紫外光、可见光和模拟日光的照射下具有最好的光催化效果,优于目前应用最广泛的市售P25。另外,所制备的光催化材料Ag₂S/ZnO经4次循环使用后,其降解效率没有明显下降,表明该催化材料具有一定的光催化稳定性。经捕获实验研究发现,在Ag₂S/ZnO的光催化反应中空穴起主要作用,并根据绝对电负性估算了复合材料Ag₂S/ZnO的能带位置,据此提出了可能的光催化反应机理。     

微波水热两步法合成高可见光响应Ag2S/ZnO及其光催化性能、机理

在不同的制备条件下,通过微波水热两步法获得了一系列Ag₂S/ZnO光催化剂,采用X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)、扫描电子显微镜(SEM)和N₂吸附-脱附等测试手段对产物结构和形貌进行了表征。结果表明,产物以六方纤锌矿ZnO为主,其晶型结构并未随着反应温度和Ag₂S物质的量的增加而改变。Ag₂S的引入显著增强了光催化剂在可见光区的吸收,使吸收边带发生红移,同时抑制了ZnO(001)晶面的生长。另外,所得产物的形貌随着Ag₂S物质的量的增加从爆米花状转变为少量的柱体颗粒,且BET比表面积经过复合后明显减小。以罗丹明B为目标降解物,研究并比较了一系列Ag₂S/ZnO光催化剂对罗丹明B的光降解性能。结果表明,n_Ag2S/n_ZnO为1:10时,光催化剂在紫外光、可见光和模拟日光的照射下具有最好的光催化效果,优于目前应用最广泛的市售P25。另外,所制备的光催化材料Ag₂S/ZnO经4次循环使用后,其降解效率没有明显下降,表明该催化材料具有一定的光催化稳定性。经捕获实验研究发现,在Ag₂S/ZnO的光催化反应中空穴起主要作用,并根据绝对电负性估算了复合材料Ag₂S/ZnO的能带位置,据此提出了可能的光催化反应机理。     

纳米结晶体Ni0.5Zn0.5Fe2O4对高氯酸铵热行为及分解反应动力学的影响

采用差示扫描量热法(DSC)、热重和微分热重(TG-DTG)及固相原位反应池/快速扫描傅立叶变换红外联用技术(hyphenated in situ thermolysis/RSFTIR)研究了纳米结晶体Ni_0.5Zn_0.5Fe₂O₄与高氯酸铵(AP)组成的混合物的热行为和分解反应动力学。结果表明：Ni_0.5Zn_0.5Fe₂O₄使得AP的低、高温分解放热峰温分别提前17.44 K和27.74 K,并使得对应的分解热分别增加3.7 J·g^-1和193.7 J·g^-1。Ni_0.5Zn_0.5Fe₂O₄并不影响AP的晶转温度和晶转热。Ni_0.5Zn_0.5Fe₂O₄使得AP的TG曲线出现3个阶段,并使得后2个失重阶段的初始和终止温度都有所提前。凝聚相分解产物分析表明Ni_0.5Zn_0.5Fe₂O₄加速了凝聚相AP的分解及氨气的释放。含Ni_0.5Zn_0.5Fe₂O₄的AP的高温分解反应的动力学参数E_a=238.88 kJ·mol^-1,A=1018.59 s^-1,动力学方程可表示为dα/dt=10^18.99(1-α)[-ln(1-α)]^3/5e^-2.87×104T。始点温度(T_e)和峰顶温度(T_p)计算得出AP的热爆炸临界温度值分别为:574.83 K和595.41 K。分解反应的活化熵(ΔS^≠)、活化焓(ΔH^≠)和活化能(ΔG^≠)分别为:109.61 J·mol^-1·K^-1、236.49 kJ·mol^-1及172.58 kJ·mol^-1。     

Zn2GeO4纳米棒的制备及发光性质

采用水热合成法制备了纯菱形相的Zn₂GeO₄纳米棒,研究了水热制备前驱体溶液的pH值对材料尺寸及形貌的影响以及Zn₂GeO₄纳米棒的光学性质。扫描电子显微镜（SEM）测试结果表明,随着前驱体溶液pH值的变化样品逐渐由微米级块状结构生长成为纳米颗粒,并且进一步形成纳米棒结构。纳米棒的尺寸由长200 nm变化到500 nm。室温光致发光（PL）光谱中观察到位于450和530 nm两个不同的发光峰,其分别源于Zn₂GeO₄的不同缺陷能级。     

(Zn，M)TiO3(M=Co，Ni，Co0.5Ni0.5)固溶体的溶胶-凝胶法合成

通过改进的溶胶-凝胶工艺在低温(800 ℃)下合成了基于钛酸锌(ZnTiO₃)体系的(Zn_1-xCo_x)TiO₃、(Zn_1-xNi_x)TiO₃和[Zn_1-x(Co_0.5Ni_0.5)_x]TiO₃陶瓷固溶体。采用X射线衍射分析(XRD)和差示扫描量热法(DSC)等测量技术对产物进行了物相和热稳定性分析。XRD结果表明，获得单一六方相(Zn_1-xCo_x)TiO₃、(Zn_1-xNi_x)TiO₃和[Zn_1-x(Co_0.5Ni_0.5)_x]TiO₃时各自的固溶稳定区间为0.5 ≤ x ≤ 1.0, 0.9 ≤ x ≤ 1.0和0.8 ≤ x ≤ 1.0。与此同时，热分析结果证实，伴随钛酸锌基陶瓷体系掺杂钴量的增加，其六方相的热稳定性提高，且效果比掺杂镍更加显著。     

Ag3PO4/MoS2纳米片复合催化剂制备及可见光催化性能

采用机械球磨法成功制备Ag₃PO₄/MoS₂纳米片复合催化剂。运用X射线衍射仪（XRD）、透射电子显微镜（TEM）、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,Ag₃PO₄纳米粒子均匀地附着在MoS₂纳米片层结构上,两者形成紧密结合。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;通过循环实验考察复合催化剂的稳定性。结果显示,含有1%的MoS₂纳米片与Ag₃PO₄形成的复合催化剂在30 min内对亚甲基蓝的降解率为95%,其降解动力学常数是纯相Ag₃PO₄的2倍。经过5次循环实验后复合催化剂对于亚甲基蓝的降解率为84%,而纯Ag₃PO₄对于亚甲基蓝的降解率仅为35%。Ag₃PO₄/MoS₂纳米片复合催化剂具有优良的光催化活性和高稳定性,主要归因于二硫化钼纳米片与磷酸银形成异质结,磷酸银激发的电子和二硫化钼纳米片产生的空穴直接复合,从而促使光生电子从磷酸银晶体表面快速分离,减轻了磷酸银的光电子腐蚀,同时也提高了复合物的光催化活性。     

Preparation and optical properties of TiO2?xNx/Ni0.5Zn0.5Fe2O4 core–shell nanocatalyst from sol–gel-hydrothermal process

A nitrogen doped TiO₂/Ni_0.5Zn_0.5Fe₂O₄ core–shell structure nanoparticles was prepared by low temperature sol–gel-hydrothermal process. The characterizations of the catalyst indicate that the Ni_0.5Zn_0.5Fe₂O₄ nanocrystals of about 25 nm are well-coated with crystalline N-doped titania. The absorption edges in the diffusion reflectance spectra of TiO_0.98N_1.02 and TiO_1.37N_0.63/Ni_0.5Zn_0.5Fe₂O₄ shift to visible light region. The core–shell nanocatalysts can effectively photodegrade organic pollutants in the dispersion system and can be recycled easily by an external magnetic field.     

Preparation of Cu-doped Cd0.1Zn0.9S solid solution by hydrothermal method and its enhanced activity for hydrogen production under visible light irradiation

A series of Cu-doped Cd_0.1Zn_0.9S solid solution with various amounts of Cu dopant was successfully prepared by hydrothermal method. The properties and the photocatalytic activity of the prepared samples for hydrogen production under visible light irradiation were compared to those prepared by co-precipitation method. The Cu-doped Cd_0.1Zn_0.9S samples prepared by hydrothermal method showed both improved crystallinity and photoabsorption ability as compared to the undoped sample. On the other hand, even though Cu-doped Cd_0.1Zn_0.9S prepared by co-precipitation method also showed improved photoabsorption ability in the visible light region, the samples showed poor crystallinity compared to the undoped one. With the same amount of Cu dopant, all samples prepared by hydrothermal method were found to exhibit higher photocatalytic activity for hydrogen production than the samples prepared by co-precipitation method. It was revealed that the amount of Cu dopant, crystallinity and narrow band gap energy are important factors to obtain highly active and stable photocatalysts.     

An Efficient and Stable MoS2/Zn0.5Cd0.5S Nanocatalyst for Photocatalytic Hydrogen Evolution

Photocatalytic hydrogen evolution by water splitting is highly important for the application of hydrogen energy and the replacement of fossil fuel by solar energy, which needs the development of efficient catalysts with long-term catalytic stability under light irradiation in aqueous solution. Herein, Zn_0.5Cd_0.5S solid solution was synthesized by a metal–organic framework-templated strategy and then loaded with MoS₂ by a hydrothermal method to fabricate a MoS₂/Zn_0.5Cd_0.5S heterojunction for photocatalytic hydrogen evolution. The composition of MoS₂/Zn_0.5Cd_0.5S was fine-tuned to obtain the optimized 5 wt % MoS₂/Zn_0.5Cd_0.5S heterojunction, which showed a superior hydrogen evolution rate of 23.80 mmol h⁻¹ g⁻¹ and steady photocatalytic stability over 25 h. The photocatalytic performance is due to the appropriate composition and the formation of an intimate interface between MoS₂ and Zn_0.5Cd_0.5S, which endows the photocatalyst with high light-harvesting ability and effective separation of photogenerated carriers.     

A highly coercive carbon nanotube coated with Ni0.5Zn0.5Fe2O4 nanocrystals synthesized by chemical precipitation-hydrothermal process

Novel magnetic composites (Ni_0.5Zn_0.5Fe₂O₄-MWCNTs) of multi-walled carbon nanotubes (MWCNTs) coated with Ni_0.5Zn_0.5Fe₂O₄ nanocrystals were synthesized by chemical precipitation-hydrothermal process. The composites were characterized by X-ray powder diffractometer (XRD), X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), etc. A temperature of about 200 °C was identified to be an appropriate hydrothermal condition to obtain Ni_0.5Zn_0.5Fe₂O₄-MWCNTs, being lower than the synthesis temperature of a single-phase Ni_0.5Zn_0.5Fe₂O₄ nanocrystals. The sizes of Ni_0.5Zn_0.5Fe₂O₄ in the composites were smaller than those of Ni_0.5Zn_0.5Fe₂O₄ nanocrystals in single phase. The composites exhibited more superparamagnetic than Ni_0.5Zn_0.5Fe₂O₄ nanocrystals in their relaxation behaviors. The magnetic properties measured by a vibrating sample magnetometer showed that the composites had a high coercive field of 386.0 Oe at room temperature, higher than those of MWCNT and Ni_0.5Zn_0.5Fe₂O₄ nanocrystals.     

Construction of CoS2/Zn0.5Cd0.5S S-Scheme Heterojunction for Enhancing H2 Evolution Activity Under Visible Light

In the field of photocatalysis, building a heterojunction is an effective way to promote electron transfer and enhance the reducibility of electrons. Herein, the S-scheme heterojunction photocatalyst (CoS₂/Zn_0.5Cd_0.5S) of CoS₂ nanospheres modified Zn_0.5Cd_0.5S solid solution was synthesized and studied. The H₂ evolution rate of the composite catalyst reached 25.15 mmol g⁻¹ h⁻¹, which was 3.26 times that of single Zn_0.5Cd_0.5S, whereas pure CoS₂ showed almost no hydrogen production activity. Moreover, CoS₂/Zn_0.5Cd_0.5S had excellent stability and the hydrogen production rate after six cycles of experiments only dropped by 6.19 %. In addition, photoluminescence spectroscopy and photoelectrochemical experiments had effectively proved that the photogenerated carrier transfer rate of CoS₂/Zn_0.5Cd_0.5S was better than CoS₂ or Zn_0.5Cd_0.5S single catalyst. In this study, the synthesized CoS₂ and Zn_0.5Cd_0.5S were both n-type semiconductors. After close contact, they followed an S-scheme heterojunction electron transfer mechanism, which not only promoted the separation of their respective holes and electrons, but also retained a stronger reduction potential, thus promoting the reduction of H⁺ protons in photocatalytic experiments. In short, this work provided a new basis for the construction of S-scheme heterojunction in addition to being used for photocatalytic hydrogen production.     

水热法制备NiS/Cd1-xZnxS及其高效光催化产氢性能

利用水热法制备 NiS 负载的 Cd1-xZnxS 光催化剂.结果表明：在0.35 mol?L-1 Na2SO3和0.25 mol?L-1 Na2S牺牲剂下,0.5%(摩尔分数, y) NiS/Cd0.3Zn0.7S (1840μmol?h-1)获得最好活性,是Cd0.3Zn0.7S (884μmol?h-1)的2.1倍,高于0.5%(质量分数, w) Pt (1390μmol?h-1)的产氢活性.测得其在λ=420 nm附近的表观量子效率为36.8%. X射线衍射(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)、透射电子显微镜(TEM)以及X射线光电子能谱(XPS)的表征结果表明, NiS作为产氢活性位,转移光生电子,因此提高了光催化产氢活性.     

ZnxCd1-xS纳米线的可控合成及其可调的光学性质

采用简单的气相沉积法,合成了不同组成的Zn_xCd_1-xS (0< x <1)纳米线. 利用扫描电子显微镜、透射电子显微镜和电子能谱研究了所制得的纳米线的表面形貌和组成. 该方法以Au为催化剂,简单控制起始物质的相对用量和沉积温度,可以获得可控的Zn/Cd 比例. X射线衍射结果表明所制得的Zn_xCd_1-xS纳米线具有纤维锌矿的单晶结构. 根据制得纳米线的表面形貌讨论了纳米线可能的生长机理为“底部生长”机理. 利用拉曼光谱和光致发光光谱研究了Zn_xCd_1-xS纳米线的光学性质,其纵向光学(LO)声子的拉曼位移频率随着组成的变化在ZnS和CdS的拉曼位移频率之间连续变化. 光致发光光谱中同时存在带边发光和缺陷发光. Zn_xCd_1-xS纳米线的带间跃迁的频率可随着组成的调节而调节,纳米线的禁带宽度介于ZnS (3.63 eV)和CdS (2.41 eV)的禁带宽度之间.     

Ag2S/Ag3PO4/Ni复合薄膜的制备及其光催化性能

采用电化学方法制备Ag_2S/Ag_3PO_4/Ni复合薄膜,以扫描电子显微镜(SEM)、X射线衍射(XRD)、紫外-可见漫反射光谱(UVVis DRS)对薄膜的表面形貌、晶相结构、光谱特性及能带结构进行了表征,以罗丹明B为模拟污染物对薄膜的光催化活性和稳定性进行了测定,采用向溶液中加入活性物种捕获剂的方法对薄膜的光催化机理进行了探索。结果表明:最佳工艺制备的Ag_2S/Ag_3PO_4/Ni是由均匀的球形纳米颗粒构成的薄膜,其光催化活性明显优于纯Ag_3PO_4/Ni薄膜和纯Ag_2S/Ni薄膜,且在保持薄膜光催化活性基本不变的前提下可循环使用6次。提出了可见光下Ag_2S/Ag_3PO_4/Ni复合薄膜光催化降解罗丹明B的反应机理。     

Anti-fungal activity of SiO2/Ag2S nanocomposites against Aspergillus niger

Submicron particles of amorphous SiO₂ have been used to grow Ag₂S nanophases at their surfaces. SEM and TEM analysis showed morphological well-defined nanocomposite particles consisting of Ag₂S nanocrystals dispersed over the silica surfaces. These SiO₂/Ag₂S nanocomposites were investigated as anti-fungal agents against Aspergillus niger in different experimental conditions, including as nanofillers in cellulosic fibres. The anti-fungal activity in these composite systems is suggested to result from a synergistic effect due to Ag₂S anti-fungal centres and the SiO₂ surfaces in promoting the adsorption of the fungus.