Morphological,optical, structural and photoelectrochemical properties of TiO2 nanoflower prepared via PVP surfactant assisted liquid phase deposition technique

This paper reports the synthesis of TiO₂ nanoflowers as photovoltaic materials of the photoelectrochemical cell (PEC) via the phase liquid deposition technique assisted with a polyvinylpyrrolidone (PVP) surfactant. This work investigates the influence of the surfactant concentration on the morphological, optical, phase structure and PEC properties of the TiO₂ PEC cell. The grain size of the TiO₂ sample decreases with increase in PVP concentration. The smallest grain size of 16 ± 2 nm is obtained at 8 mM PVP. The thickness of the sample increases with PVP concentration. The concentration of PVP does not influence the optical absorption and band gap of the sample. The phase structure and crystallinity degree of the sample are not influenced by PVP concentration. The crystallite size is around 20 nm. The short-circuit current density, J_sc, of the PEC cell utilising these TiO₂ samples increases with decrease in grain size which is due to the increase in PVP concentration. The best J_sc was 0.068 mA cm^?2 obtained at 8 mM PVP.     

The effects of thioacetamide/copper molar ratio and reaction time on the phase evolution,morphology, optical,and photocatalytic properties of the nanosheets-based flower-like copper sulfide

In this paper, various morphologies including spherical and flower-like nanosheets-based CuS were synthesized by the green hydrothermal synthesis method. Copper (II) nitrate trihydrate and thioacetamide (TAM) were selected as a Cu²⁺ and sulfur source, respectively. The effects of TAM/Cu molar ratio and reaction time on the phase and morphological evolution of the samples were studied. For this purpose, the samples were distinguished by FT-IR, FE-SEM, XRD, and ultraviolet-visible spectroscopy. The photocatalytic and optical properties of the products were evaluated. It was found that self-organized nanoflower(SONF) structures exhibit very good photocatalyst efficiency to degrade organic dye due to a significant increase in their surface area because of decorated nanosheets on the sample. Therefore, the SONF structures exhibited a very suitable potential as the photocatalyst agents.     

基于离子液体辅助下微波加热快速合成花状氧化锌纳米粒子

以二水合醋酸锌（Zn（AcO）2·2H2O）和氢氧化钠（NaOH）为原料,采用微波辅助加热,以离子液体作为微波吸附剂和表面活性剂,制备花状纳米氧化锌。用X射线衍射（XRD）,扫描电子显微镜（SEM）,荧光光谱仪（PL）对产物的晶相,微观形貌和发光特性进行表征。结果表明,产物是纤锌矿结构ZnO,呈花状,分散性好,光致发光光谱显示样品在421nm处显示出紫色发光峰,在542nm处显示出绿色发光峰。     

多孔ZnO纳米花电子传输层对有机太阳能电池性能的优化

通过水热法制备了多孔、单晶结构的三维ZnO纳米花材料。研究了不同生长时间下(6h、9h和12h)的ZnO材料的形貌及光电性能。结果表明,反应9h的多孔ZnO纳米花材料具有较高透光率、低缺陷密度以及高载流子迁移率等优点,是较为理想的电子传输层材料。将这些材料应用于有机太阳能电池的制备,性能测试结果表明,以生长时间为9h的多孔ZnO纳米花材料作为电子传输层的器件性能最佳,与无ZnO修饰层的参比器件相比,其短路电流密度Jsc和光电转化效率(PCE)明显提高,分别达到了5.68mA/cm2和1.24%。     

Synthesis of silver@platinum-cobalt nanoflower on reduced graphene oxide as an efficient catalyst for oxygen reduction reaction

A novel oxygen reduction reaction (ORR) electrocatalyst silver@platinum-cobalt-rGO nanoflower (Ag@PtCo-rGO NFs) is prepared by hydrothermal reduction method. The formation of silver chloride likes elm leaf microstructure in the reaction process, performing as a template. The Ag@PtCo-rGO NFs exhibit excellent electrocatalytic activity, whose specific activity is 9 times higher than that of commercial Pt/C. More importantly, Ag@PtCo-rGO NFs demonstrate excellent durability than JM Pt/C for ORR in acid media, as evidenced by accelerated durability test after 40,000 cycles. These excellent performances can be attributed to the special structure, atomic steps and synergistic effect between Pt, Ag and Co. The density functional theory calculation shows that Ag@PtCo has the best activity, which is related to the transition state for O–O bond. This work proposes a promising pathway for the synthesis of surfactant-free nanoflowers structure catalysts with high catalytic performance and low cost.     

纳米花固定化葡萄糖异构酶的制备及性能分析

该研究采用共沉淀法制备了葡萄糖异构酶（Glucose Isomerase,GI）纳米花,对固定化条件进行了优化,同时对纳米花固定化酶的形态特征以及酶学性质进行了探究。结果表明,40 μL酶液中加入9 mL、pH值7.4的PBS缓冲液后与30 μL CuSO4混合,在35 ℃条件下静置反应18 h,制得的纳米花固定化葡萄糖异构酶（Glucose Isomerase @ Nano flowers,GI@NFs）的酶活回收率高达183.06%。SEM表征结果显示GI@NFs有完整的纳米花结构,傅里叶红外光谱显示GI@NFs具有酶和PO43-的特征吸收,X-射线衍射结果进一步证明其载体为Cu3(PO4)2。酶学性质研究发现,GI@NFs的最适反应温度为60 ℃,比自由酶的提高了10 ℃;最适反应pH值为8,比游离酶的最适pH更高;GI@NFs的温度稳定性和pH稳定性均比自由酶的明显提高;固定化酶被循环使用8次,其酶活力仍保持最初活力的60.32%。实验结果表明,纳米花结构提高了葡萄糖异构酶的酶活,表现出较好的循环性能和稳定性,具有一定的应用价值。     

硫化钨纳米花的制备及其在染料降解中的应用

以钨酸钠、硫脲、草酸为原料,采用水热法制备出由纳米薄膜组装而成的WS_2纳米花(WS_2NF)。反应过程中,硫脲的包覆作用和草酸的偶联作用,协同控制WS_2的增长,最终形成花瓣状结构。所制备的WS_2NF具有形变能力强、机械能捕获面积大、传质效率高和活性位点丰富的优点,有效提高了WS_2材料的压电催化性能,在5min内可将难降解有机染料完全降解,且该材料多次重复使用后依然保持高活性。     

Radial porous SiO2 nanoflowers potentiate the effect of antigen/adjuvant in antitumor immunotherapy

Here, we reported a cancer nanovaccine based on SiO₂ nanoflowers with a special radial pore structure, which greatly enhanced cross-presentation and induced the production of cytotoxic T lymphocyte cells secreting granzymes B and interferon-γ. The antigen ovalbumin was covalently conjugated onto the as-synthesized hierarchical SiO₂ nanoflowers, and the adjuvant cytosine-phosphate-guanine was electrostatically adsorbed into their radial pore by simple mixing before use. The nanovaccine exhibited excellent storage stability without antigen release after 27 days of incubation, negligible cytotoxicity to dendritic cells, and a high antigen loading capacity of 430 ± 66 mg·g⁻¹ support. Besides, the nanovaccine could be internalized by dendritic cells via multiple pathways. And the enhancement of antigen/adjuvant uptake and lysosome escape of antigen were observed. Noteworthy, in vitro culture of bone marrow-derived dendritic cells in the presence of nanovaccine proved the activation of dendritic cells and antigen cross-presentation as well as secretion of proinflammatory cytokines. Besides, in vivo study verified the targeting of nanovaccine to draining lymph nodes, the complete suppression of tumor in six out of ten mice, and the triggering of notable tumor growth delay. Overall, the present results indicated that the nanovaccine can be served as a potential therapeutic vaccine to treat cancer.     

纳米Cu2O花的制备及其光学性质研究

以Cu(CH3COO)2.H2O为原料,CTMAB(十六烷基三甲基溴化铵)和NaOH为添加剂,NaBH4为还原剂,通过液相法在低温(60℃)的条件下分步合成了纳米Cu2O花。采用XRD、SEM、TEM和紫外–可见吸收光谱分析等手段对纳米Cu2O花进行了表征。结果表明,纳米Cu2O花的生长过程符合成核–溶解–再结晶的机制。对照实验发现,NaOH和CTMAB的浓度对最终纳米花的形成起了关键性的作用。     

Graphene‐wrapped poly(2,5‐dihydroxy‐1,4‐benzoquinone‐3,6‐methylene) nanoflowers as low‐cost and high‐performance cathode materials for sodium‐ion batteries

Graphene‐wrapped poly 2,5‐dihydroxy‐1,4‐benzoquinone‐3,6‐methylene (PDBM) nanocomposites with three‐dimensional nanoflower structures have been successfully prepared through the ultrasonic exfoliation and reassembly process in methanol. Compact distribution of graphene into the nanocomposite has established a three‐dimensional conductive network, which contributes to improved properties on discharge capacity and cycle performance. Composite with 20 wt% graphene was proved the best ratio when used in sodium‐ion batteries. Its initial discharge capacity can achieve 210 at 30 mA g^?1. After 100 cycles, the capacity is stable at 121 mAh g^?1. The composite featuring highly conductive channels and multidimensional electron transport pathway is synthesized by an easy ultrasonic way, which may be applied in large scales for sodium‐ion batteries.