近红外光驱动的UCNPs/ZnxCd1-xS纳米复合结构的化学合成并用于光化学还原六价铬

近红外光约占入射太阳能的 44% 以上, 为实现太阳能量的最大化利用, 近红外光 (NIR) 驱动的光催化技术成为科学研究的热点. 由于上转换荧光纳米材料 (UCNPs) 是优良的红外能量转换器, 合金半导体 ZnxCd1-xS 具有较好的化学稳定性以及生物相容性, 本文发展了一种简易的水热法, 将 UCNPs 和 ZnxCd1-xS 合金结合, 成功构建了 NIR 与可见光响应的核壳纳米结构. 由于这两种材料的晶格失配度较高, 很难直接外延生长, 我们通过引入非晶 TiO2将形成的催化剂纳米颗粒ZnxCd1-xS 紧紧束缚在 UCNPs 外面形成蛋黄-蛋壳结构, 在 NIR 光照下获得了较高的能量转换效率.首先, 在 UCNPs 外面外延生长一层 AA-Zn[(OH)4]2–复合物, 形成 UCNPs@AA-Zn[(OH)4]2–复合纳米结构, 然后在其核壳结构外面外延生长薄层的非晶 TiO2, 以稳定后续要制备的合金半导体 ZnxCd1-xS; 在水热条件下, UCNPs@AA-Zn[(OH)4]2–/TiO2与醋酸镉和硫脲反应, 形成 UCNPs@ZnxCd1-xS/TiO2复合材料. 在此, 我们选择β-NaYF4:Yb(30%),Tm(0.5%)@NaYF4:Yb(20%),Er(2%) 作为 NIR 的能量转换器. 样品的形貌、物相及化学组成分别采用场发射扫描电子显微镜、透射电子显微镜、X 射线衍射和原子吸收光谱法进行表征.研究表明, 我们成功制备了具有蛋黄-蛋壳结构的 UCNPs@ZnxCd1-xS/TiO2纳米颗粒. 此外, 非晶态 TiO2将 UCNPs 与ZnxCd1-xS 紧密结合, 对最终样品 UCNPs@ZnxCd1-xS 核壳纳米粒子的形成起到重要作用. 而且, 合金 ZnxCd1-xS 的化学组成可通过调整镉源和锌源的用量进行调节. 所制备的 UCNPs@ZnxCd1-xS 核壳纳米粒子在 NIR 光线或模拟太阳光照射下显示出高效的光化学还原 Cr(VI) 性能. 溶液中 70% 以上的 Cr(VI) 在 NIR 光照射 30 min 后被还原为 Cr(III). 本研究将为环境污水处理和太阳能利用提供一种可供选择的策略, 且所制的复合纳米结构在肿瘤治疗、药物释放和能量转换等领域也有着潜在的应用价值.     

蛋黄-壳结构Fe3O4@SiO2@PMO磁性微球的制备及对漆酶的固定化

以蛋黄-壳结构的Fe₃O₄@SiO₂@PMO磁性微球作为载体, 采用交联法对漆酶进行固定, 考察了戊二醛浓度等对固定效果的影响, 并对固定后漆酶的活性进行了研究. 结果表明, 蛋黄-壳结构的磁性微球负载漆酶仅需6 h, 磁性微球对漆酶的固载量高达475 mg/g. 固定后漆酶的稳定性显著提高, 在pH=2.5~4.5的强酸性条件下, 固定后漆酶酶活仍可保持70%以上, 即使温度升高至60 ℃, 固定后漆酶的相对酶活仍保持65%以上. 这说明漆酶经所合成的材料固定后, 其耐酸和耐热能力都明显优于游离漆酶. 包覆的Fe₃O₄粒子使得材料很容易经磁铁分离法回收, 固定后漆酶经磁分离循环使用10次后仍然能保留85%的酶活, 具有良好的可操作性和稳定性, 有效降低了漆酶的使用成本.     

Yolk-shell structured Fe@void@mesoporous silica with high magnetization for activating peroxymonosulfate

Sulfate radical anion (SO₄^⿢⿿) based Fenton-like reaction have recently received a large quantity of attention owing to their strong oxidative capacity and high selectivity toward organic pollutants. However, the development of a high-efficient catalyst for activation of peroxymonosulfate (PMS) with a fast separation is still challengeable. Herein, magnetic mesoporous silica composites with a yolk-shell structure (Fe@void@mSiO₂) have been prepared via a successive coating strategy, followed by a high-temperature in-situ treatment and demonstrated as a high-efficient and fast magnetic separable catalyst for the activation of PMS. The resultant material possesses a well-defined yolk⿿shell structure with high specific surface area (⿼495.0⿿m²/g), uniform pore size (⿼6.9⿿nm) and super large magnetic susceptibility (⿼105⿿emu/g). Owing to the unique properties, the material possesses an excellent degradation activity for tetracyclines (TC), which is much higher than the commercialized Zero Valent Iron (ZVI) nanoparticles. Additionally, the catalyst is able to work over a broad pH range and be quickly recycled by using an external magnetic field. This research provides a promising strategy for the synthesis and design of multifunctional catalyst for the Fenton-like process.     

先进蛋黄-蛋壳结构能源转化纳米反应器

蛋黄-蛋壳结构独特的纳米结构及特性,使其在很多领域中具有潜在的应用价值,因此近年来受到了广泛关注.本综述总结了使用蛋黄-蛋壳纳米结构作为纳米反应器的研究进展.从合成策略出发,主要强调最近五年合成蛋黄-蛋壳纳米结构的最新研究进展.通过光催化,甲烷重整和电催化等反应作为典型的反应过程,重点讨论蛋黄-蛋壳结构纳米反应器在催化领域的应用,并对该领域未来的发展进行了展望.     

Yolk-shell nanostructural Ni_2P/C composites as the high performance electrocatalysts toward urea oxidation

Highly active and low-cost catalytic electrodes for urea oxidation reaction(UOR) are always crucial for exploration of urea fuel cells.Herein,novel york-shell-structural Ni_2P/C na nosphere hybrids(Ni_2P/C-YS)are rationally constructed via a hydrothermal method and subsequent phosphidation treatment under different temperature ranging from 250℃ to 450℃ for UOR applications.In the in-situ constructed hollow york-shell structure,the coupling of conductive carbon materials and active Ni_2P allows numerous interfaces facilitating the electron transfer and thereby accelerating the catalytic kinetics.The results demonstrate that Ni_2P/C-YS-350 nanocomposite can boost the UOR process with a low potential of 1.366 V vs.RHE at a current density of 50 mA/cm~2 in alkaline electrolyte and afford the superior durability with negligible potential decay after 23 h.This study presents that the carbon coated Ni_2P hybrid with the optimized crystallinities and hollow york-shell configurations can be a promising candidate for application in urea fuel cells.     

Self-assembly of homopolymer of PAA-NH4

PAA-NH₄ assemblies varying from nanospheres to large particles and yolk-shell vesicles were obtained by adding different amount of HCl solution into the dispersion of PAA-NH₄ in ethanol, which may be extended the practical application due to the simple polymers used.     

A confined micro-reactor with a movable Fe3O4 core and a mesoporous TiO2 shell for a photocatalytic Fenton-like degradation of bisphenol A

Photocatalysis and Fenton process are two primary and promising advanced oxidation processes to degrade organic pollutants. However, the practical applications of single photocatalysis and Fenton process are still limited. Introducing one of them into another to form a combined photocatalytic Fenton-like system has shown great potential but still faces challenges in designing a well-tailored catalyst. Herein, a confined photocatalytic Fenton-like micro-reactor catalyst with a movable Fe₃O₄ core and a mesoporous TiO₂ shell has been constructed via a successive Stöber coating strategy, followed by an ultrasound assisted etching method. The resulting micro-reactor possesses well-defined yolk-shell structures with uniform mesopores (～4 nm), a large Brunauer-Emmett-Teller (BET) surface area (～166.7 m²/g), a high pore volume (～0.56 cm³/g) and a strong magnetization (～51 emu/g), as well as tunable reactor sizes (20?90 nm). When evaluated for degrading bisphenol A under solar light in the presence of peroxymonosulfate, the micro-reactor exhibits a superior catalytic degradation performance with a high magnetic separation efficiency and an excellent recycle ability. The outstanding performance can be attributed to its unique textual structure, which leads to a great synergistic effect from the photocatalytic and Fenton-like process. This study gives an important insight into the design and synthesis of an advanced micro-reactor for a combined advanced oxidation processes (AOPs).     

Engineering of yolk-shelled FeSe2@nitrogen-doped carbon as advanced cathode for potassium-ion batteries

Potassium-ion batteries (KIBs) have become the most promising alternative to lithium-ion batteries for large-scale energy storage system due to their abundance and low cost. However, previous reports focused on the intercalation-type cathode materials usually showed an inferior capacity, together with a poor cyclic life caused by the repetitive intercalation of large-size K-ions, which hinders their practical application. Here, we combine the strategies of carbon coating, template etching and hydrothermal selenization to prepare yolk-shelled FeSe₂@N-doped carbon nanoboxes (FeSe₂@C NBs), where the inner highly-crystalline FeSe₂ clusters are completely surrounded by the self-supported carbon shell. The integrated and highly conductive carbon shell not only provides a fast electron/ion diffusion channel, but also prevents the agglomeration of FeSe₂ clusters. When evaluated as a conversion-type cathode material for KIBs, the FeSe₂@C NBs electrode delivers a relatively high specific capacity of 257 mAh/g at 100 mA/g and potential platform of about 1.6 V, which endow a high energy density of about 411 Wh/kg. Most importantly, by designing a robust host with large internal void space to accommodate the volumetric variation of the inner FeSe₂ clusters, the battery based on FeSe₂@C NBs exhibits ultra-long cycle stability. Specifically, even after 700 cycles at 100 mA/g, a capacity of 221 mAh/g along with an average fading rate of only 0.02% can be retained, which achieves the optimal balance of high specific capacity and long-cycle stability.     

“蛋黄-蛋壳”结构纳米反应器的设计、调控及在锂硫电池正极中的应用研究

锂硫电池具有理论能量密度高等优势,被认为是最有前景的一类新型二次电池.硫正极存在硫和硫化锂的导电性差、可溶性多硫化物的扩散/穿梭、循环过程中硫的体积膨胀以及氧化还原过程慢等问题,严重制约着电池的活性和循环稳定性.设计“蛋黄-蛋壳”结构纳米反应器应用于锂硫电池正极,可通过调控其“蛋黄”、“蛋壳”和“空腔”结构缓解充放电过程中电极的体积变化,为离子/电子输运提供快速通道,强化对多硫化物的吸附和催化转换作用等,进而提高电极的活性和循环性能,有利于推进锂硫电池的商业化进程.本文总结了“蛋黄-蛋壳”结构纳米反应器的设计和调控策略,包括单核-单壳、单核-多壳、多核-单壳以及多核-多壳等,并结合锂硫电池的工作特点和目前应用存在的问题,对未来发展前景进行了展望.     

Synthesis and Characterization of Cu Decorated Zeolite A@Void@Et-PMO Nanocomposites for Removal of Methylene Blue by a Heterogeneous Fenton Reaction

Hydrothermal synthesized nano zeolite A has been encapsulated with ethyl bridged periodic mesoporous organosilica(Et-PMO) shell tlirougli a simple modified Stober method and an organosilane-directed growth-induced etching strategy, the obtained yolk-shell structured A@Et-PMO nanocomposite(YS-A@Et-PMO) was further functionalized by the impregnation of copper ions, realizing the composite material with hierarchical porous and catalytic properties. The morphology and metal content of the Cu/A and Cu/YS-A@Et-PMO were fully characterized. As compared to tlie parent material, the composite Cu/YS-A@Et-PMO has an efficient adsorption and catalytic degradation performance on methylene blue(MB), the removal efficiency reached as high as 95% of 60 mg/L MB within 10 min. These novel structured porous composites may have great potential application for the removal of organic dye including waste effluents.