以聚酰胺-胺树形分子为模板制备AgI纳米簇

本文以聚酰胺-胺(PAMAM)树形分子为模板,原位制备AgI纳米簇.系统地研究了AgI纳米簇制备过程中各种反应条件如树形分子端基、反应时间、Ag 与PAMAM摩尔比等对AgI纳米簇粒径的影响,分别用紫外-可见光谱、荧光光谱、透射电镜等对所制备的纳米簇进行表征.在相同的条件下,以G4.5-COOH3为模板较以G5.0-NH2为模板制备的AgI纳米簇粒径小、分布均匀,这主要取决于G4.5-COOCH3PAMAM树形分子所起的“内模板”作用.G4·5-COOH3树形分子浓度为1×10-5mol/L,Ag 与树形分子摩尔比为30∶1时所制备的AgI纳米簇的粒径分布均匀、稳定性好,室温避光可稳定存在两个月以上.     

Novel direct Z-scheme AgI/N–TiO2 photocatalyst for removal of polluted tetracycline under visible irradiation

In the study, we doped N into TiO₂ lattice to narrow its band gap energy. Then, the synthesized N doped TiO₂ material was combined with AgI to form AgI/N–TiO₂ (ANT) direct Z scheme materials. The synthesized materials were utilized for photocatalytic removal of tetracycline (TC) using visible irradiation as an excitation source. We also conducted radical scavenging experiments to determine photocatalytic degradation mechanism. We investigated that these photo-excited electrons (e⁻) in N–TiO₂ conduction band tended to combine with the left holes (h⁺) in AgI valence band maintaining h⁺ in the valence band of the N–TiO₂ and e⁻ in the conduction band of the AgI. The remained e⁻ and h⁺ have high redox potential to initiate for photocatalytic decomposition of TC. Thus, the TC degradation by the ANT materials were significant greater than those by single components (AgI or N–TiO₂). We also investigated that the TC degradation by the ANT-30 material, which the AgI: N–TiO₂ molar ratio was 30%, exhibited that highest degradation efficiency. Finally, the ANT photocatalyst exhibited excellent stability during TC degradation processes supporting for its promising potential application in practical systems.     

人工影响天气纳米碘化银催化剂的制备及表征

采用沉淀法在常温常压下制备了纳米碘化银粒子,对试剂含量(硝酸银浓度、碘化钾浓度、络合剂浓度及分散剂浓度等)及工艺条件对纳米碘化银粒子形态的影响进行了研究。利用透射电子显微镜和X-射线衍射仪分析了纳米粒子的微观形貌及相结构。结果表明:纳米碘化银粒子成球形,粒径均匀可控,无明显团聚现象,不同工艺条件下获得的碘化银粒径不同,最大粒径范围在80～90nm,最小粒径范围在25～30nm,因为碘化银具有类冰结构,是最佳成冰物质,故纳米碘化银粒子作为人工影响天气催化剂具有极大的应用前景。     

由配合物制备AgI纳米粒子

改进传统的共沉淀法，由Ag(NH3)2^ 与KI溶液混合，制备了均匀球形的AgI纳米粒子，研究了反应条件（银配合物浓度、氨浓度、反应时间等）对AgI粒子形态的影响，并进行了X射线衍射及透射电镜的分析。     

(纳米MCM-41)-AgI主-客体复合材料的制备及表征

采用水热合成法制备了纳米MCM-41,并用热扩散法将半导体材料AgI装入其中,制备了(纳米MCM-41)-AgI复合材料,同时制备了用来比较的(微米MCM-41)-AgI复合材料,并以粉末XRD、红外光谱、N2吸附等技术对所得样品进行了表征。粉末XRD分析结果表明:AgI组装进MCM-41孔道后,MCM-41仍能保持其骨架结构;红外光谱表明:组装AgI后样品的骨架振动峰蓝移,这主要是由组装了AgI引起的。吸附研究表明:AgI已进入MCM-41孔道内。通过比较,AgI的进入对纳米MCM-41的影响大于微米MCM-41。样品的固体扩散漫反射吸收光谱和发光研究表明:所制备的2种样品表现出明显的立体限域效应和量子尺寸效应,在(纳米MCM-41)-AgI材料中立体限域效应和量子尺寸效应尤为突出。     

微米银粉表面碘化改性工艺参数对其形貌的影响

以I₂作氧化剂与微米级银颗粒反应,产生AgI,利用其光敏性使AgI分解成纳米银颗粒,最终在微米银颗粒表面负载Ag/AgI纳米团簇,考察了碘银摩尔比、银粉添加方式及后处理曝光方式对微米级银颗粒表面形貌的影响。结果表明,银粉的形貌与碘银摩尔比正相关;Ag/AgI纳米团簇的形貌与尺寸可通过银粉添加方式及后处理曝光方式进行微调。当碘银摩尔比为2∶100时,经直接添加银粉和再分散曝光法制备的银粉表面纳米团簇的粒径小且分布窄。     

AgI/BiPO4异质结的原位制备及光催化性能

采用水热合成法制备了磷酸铋(BiPO4),通过沉淀法成功将AgI负载于BiPO4表面制备了AgI/BiPO4异质结。采用X射线衍射仪(XRD)、紫外-可见漫反射光谱(UV-Vis DRS)等对AgI/BiPO4异质结结构和组成进行了表征;用表面光电压谱(SPS)对异质结光催化剂的光生电荷分离特性进行了研究;考察了AgI/BiPO4异质结光催化剂对模拟污染物罗丹明B的催化降解性能。结果表明,当AgI/BiPO4摩尔比为1.2%时,异质结光催化剂的光生电子-空穴分离速率最高,对罗丹明B的光催化降解性能最好。光催化过程中主要活性自由基为超氧自由基.O2^-,h⁺空穴和.OH自由基是起次要作用的活性自由基。     

Growth and quantum confinement in AgI nanowires

Silver iodide nanowires were synthesized in W/O microemulsions by using cyclohexane/Triton X-100/n-pentanol system. Most likely, surfactants form rod-like aggregates that can serve as template for growth of two dimensional nanomaterials. It was found that the length of the AgI nanowires increases as a function of aging time, while the diameter decreases. Final length of the AgI nanowires is several microns, while the diameter is smaller than 3 nm. Morphological changes are accompanied by optical and structural changes. Large blue shift of excitonic peak from bulk value at 420 to 326 nm was observed as a consequence of the size quantization effect. Decrease of diameter is followed by the amorphization of AgI nanowires.     

Construction of ternary heterojunction AgI/C--MoS2 nanosheets with enhanced visible-light photocatalytic property and self-cleaning performance

Carbon–molybdenum disulfide (C–MoS₂) ultrathin nanosheets were prepared by a hydrothermal process, and then AgI/C–MoS₂ were synthesized via an in-situ deposition method. This ternary heterojunction composite exhibited better photocatalytic activity compared with those of one-component (pristine MoS₂) and bi-component (AgI/MoS₂ and C–MoS₂) materials for the degradation of organic dyes under the visible-light irradiation. In particular, by comparing with AgI/MoS₂, the significant role of conductive amorphous carbon in AgI/C–MoS₂ in enhancing the charge transfer during the photocatalytic degradation of dyes was first confirmed by photocurrent response and electrochemical impedance spectroscopy (EIS). A possible photocatalytic mechanism was proposed based on the capture experiment results. Furthermore, a straightforward and interesting way had been applied to test the recycled/newly-prepared AgI/C–MoS₂ composite for revealing its distinctive self-cleaning performance and recyclability characteristic besides its good photocatalytic activity. This work could provide a reference for the design of other new ternary heterojunction composite materials with special structures and properties.     

AgI纳米粒子水溶胶的制备与表征

采用沉淀法制备了AgI纳米粒子水溶胶，对制备水溶胶的条件进行了系统的研究。TEM分析表明，AgI纳米粒子呈球形，粒径小于50nm，粒径分布均匀，无明显团聚现象；ED分析表明，AgI纳米粒子为多晶结构，其中有少量的发育良好的单晶颗粒存在。