Lanthanide-organic-frameworks modified ZnIn2S4 for boosting hydrogen generation under UV–Vis and visible light

Novel Ln-MOF with microrods shape were successfully combined with ZnIn₂S₄ (ZIS) microsphere and used for photocatalytic hydrogen generation under UV–Vis and visible light. The Ln-MOFs/ZIS system comprises lanthanide-carboxylate coordination networks (Tm and Gd as metal ions, and 1,3,5-benzenetricarboxylic acid (BTC) as the organic linker) deposited on ZnIn₂S₄ microspheres. Effect of the amount of ((Tm,Gd)-BTC) (1, 5, 10 wt%) on the optical properties and photocatalytic hydrogen evolution performance was investigated. ZIS microsphere shows the marigold flower-like morphology and hexagonal polytopic crystal form. Our results proved that the combination of ZIS microsphere, Ln-MOF and Pt nanoparticles (NPs) caused significant enhancement in hydrogen generation. Amount of formed hydrogen was raised from 196.3 to 7782.1 μmol g^?1 for pristine ZIS and ZIS decorated with 1% (Tm, Gd)-BTC/Pt under UV–Vis light, respectively.     

Enhanced photoreactivity of MOFs by intercalating interlayer bands via simultaneous ?NCO and ?SCu modification

Herein, we propose a novel method to enhance the photoreactivity of an MOF catalyst by grafting isocyanate bonds ( NCO) and sulfhydryl-complexed copper ( SCu) onto ZIF-8 (NIF-SCu). The grafting process intercalated interlayer bands between the conduction and valence bands of ZIF-8, thereby providing a “ladder” for facile electron transition. The extreme improvement in the photoreactivity of NIF-SCu could be attributed to the enhancement in light responses in the range of 350–450 nm by  NCO groups and the widening of the visible light range of the MOF by  SCu groups. The formation of staggered energy levels in NIF-SCu could also narrow the band gap, lower the resistance, and facilitate the transfer of photogenerated carriers, thereby generating electrons with strong reduction potential in the  SCu conduction band. This study provides a new strategy for improving or even endowing the photoactivity of environmental functional materials with wide bandgaps.     

Genesis of enhanced photoactivity of CdS/Nix nanocomposites for visible-light-driven splitting of water

A series of CdS/Ni_x nanocomposite photocatalysts, containing ca. 0.6–15 wt% Ni, were synthesized using a one-step hydrothermal method and characterized for their crystallographic, morphological, interfacial, and optical properties. Rietveld refinement of powder XRD data revealed the coexistence of wurtzite (hexagonal) and zinc blende (cubic) phases of CdS in ratios dependent on Ni content. Only a fraction of Ni existed as a secondary phase of NiS while the majority occupied the lattice positions of hexagonal CdS. Whereas up to 10-fold enhancement in H₂ evolution compared with pure CdS was observed for samples containing ∼1.5–4.5 wt% Ni, samples with smaller or larger Ni content displayed poor activity for visible-light-induced splitting of water in presence of sulfide–sulphite ions as sacrificial electron donors. In contrary to recent findings, our study reveals that the enhanced CdS photoactivity is not a result of charge transfer between p-type NiS and n-type CdS, Ni-induced visible-region absorbance, or the coating of CdS particles by non-photoactive NiS. Instead, the preparation-dependent hexagonal/cubic CdS phase boundaries and particle morphology may play a crucial role. Additionally, certain Ni-doping-induced sub-bandgap shallow energy levels contribute to charge carrier separation.     

pH敏感锌酞菁聚合物的制备及光活性

将四马来酰胺基锌酞菁与甲基丙烯酸二乙胺基乙酯共聚,制备出一种具有pH敏感的锌酞菁聚合物。该聚合物能溶解于酸性水溶液和乙醇,并且在水溶液中表现出良好的可逆pH敏感响应特性。通过该锌酞菁聚合物对单线态氧捕捉剂1,3-二苯基苯并呋喃和L-色氨酸的光催化降解测试,发现其在可见光照射下具有较高的光活性。基于上述性能,该pH敏感锌酞菁聚合物作为一种新型光敏剂,有望在光动力学治疗领域得到应用。     

Photocatalysis of methylene blue on titanium dioxide nanoparticles synthesized by modified sol-hydrothermal process of TiCl4

Titanium dioxide nanoparticles were synthesized by the hydrolysis and condensation of TiCl₄, an economic titanium precursor, in a mixed solvent of iso-propyl alcohol and water. As-prepared powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy filtering transmission electron microscopy (EF-TEM). To examine the photocatalytic activity of the as-prepared TiO₂, the photodegradation of MB which is a typical dye resistant to biodegradation has been investigated on TiO₂ powders in aqueous heterogeneous suspensions. The photocatalytic activity of TiO₂ powders prepared by the hydrolysis of TiCl₄ in the mixed solutions of iso-PrOH/H₂O exceeded that of commercial TiO₂ powders. The apparent first order rate constants (k _app) for the photodegradation of methylene blue (MB) showed a good correlation with the absorbance area obtained by UV-VIS DRS on wavelength in the limits of used lamp emission 300∼420 nm.     

Visible photoactivity and antiphotocorrosion performance of PdS-CdS photocatalysts modified by polyaniline

PdS-CdS modified by polyaniline (PANI) as a novel photocatalyst was synthesized via a sonochemical approach for the first time. The as-prepared photocatalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis absorption spectra, FT-IR spectra, and fluorescence spectra (PL). Under visible light, the photocatalysts showed excellent photocatalytic activity for hydrogen evolution in the absence of noble metal Pt and the antiphotocorrosion performance of the composite photocatalyst was also found to be significantly improved simultaneously compared to PdS-CdS without PANI modification. The highest rate for H₂ evolution was 3.32 mmol/h with the concentration of 1 wt.%PANI and 1 wt.%PdS.     

联苯双(环左二烯-铁)二价阳离子作为环氧化合物聚合的有效的阳离子光聚合引发剂

Ferrocenium monocations as photoinitiators for cationic photopolymerization suffer from a limitation of low absorption and low reactivity under high-pressure Hg lamp.Here,a ferrocenium dication salt,biphenyl bis [(π-cyclopentadienyl)iron]hexafluorophosphate[bis(Cp-Fe)-biphenyl](PF6)2 was synthesized by the ligand ex-change reaction between ferrocene and biphenyl.The chemical structure was characterized with FTIR and HNMR.The separation of ferrocenium monocation cyclopentadien-iron-biphenyl hexanuorophosphate([Cp-Fe-biphenyl]PF6) and dication [bis(Cp-Fe)-biphenyl](PF6)2 was carried out by coulumn chromatography.The photoactivity of initiating photolymerization of epoxide ERl4221 was studied as a cationic photoinitiator.[Bis(Cp-Fe)-biphenyl](PF6)2 can efficiently absorb radiation above 300nm and its photoactivity is higher than that of its monocation.     

核壳结构CdS/TiO2的制备与表征

通过水热法合成分散性良好的CdS纳米颗粒,并采用声化学法在颗粒外包覆TiO2壳层,获得的复合材料具有更好的光催化特性.讨论了水热反应温度保温时间与晶粒尺寸、结晶性之间的关系以及声化学制备过程中反应条件与陈化时间对壳层生长的影响.采用X射线衍射、透射电镜、漫反射光谱、光催化性能测试等手段表征CdS颗粒的尺寸、形貌及CdS/TiO2的结构与光催化特性.结果表明水热过程中,提高反应温度、保温时间有利于提高产物的结晶性.声化学合成CdS/TiO2复合材料过程中,超声作用能促进核壳结构的形成.提高前驱溶液的浓度,在获得CdS/TiO2核壳结构的同时会析出TiO2纳米粒子.在降解甲基橙的实验中,CdS/TiO2材料表现出比单组分材料更好的催化性能.     

N掺杂TiO2纳米粉体的表面特性及可见光活性

旨在探究N掺杂纳米TiO2具有可见光活性的本质,采用XPS、ESR、XRD、SEM、DRS、SPS和PL分析技术对sol-gel法制备的未掺杂和N掺杂TiO2纳米粉体进行了对比研究,并以亚甲基蓝(MB)溶液在可见光下的光催化脱色评价其可见光活性。结果表明,N掺杂TiO2纳米粉体具有良好的可见光活性,未掺杂样品几乎没有可见光活性。N取代TiO2晶格中O形成了N─Ti─O和O─N─Ti键合结构产生杂质能级,N掺杂导致TiO2表面形成了大量束缚单电子的氧空位产生缺陷能级,二者协同作用致使带隙窄化,光吸收带边红移,产生可见光活性。N掺杂导致TiO2晶格中p-n结的形成及表面氧空位和表面羟基的增加均能促进光生e-/h+分离,有效抑制光生e-/h+复合,提高量子效率,进而提高其光活性。     

用表面处理法降低TiO_2粉末光活性问题的研究

本工作采用了两种简便的方法即用不同金属盐和金属氧化物对两种晶型(锐钛矿型和金虹石型)TiO_2粉末进行表面处理来降低TiO_2的光活性并对两种表面处理方法的优缺点作了比较,在评价TiO_2光活性时采用异丙醇光氧化反应的方法。实验证明,用金属盐表面处理TiO_2,其光活性有明显降低。用金属氧化物对TiO-2进行表面处理,在氧化物/TiO_2比例适当时也可以得到与金属盐表面处理TiO_2的同样效果。此外,我们还对TiO_2表面处理后能降低其光活性的作用机制问题进行了讨论。