Macaroon-like FeCo2O4 modified activated carbon anode for enhancing power generation in direct glucose fuel cell

Macaroon-like FeCo₂O₄ nanomaterial was prepared and used as electrocatalyst in direct glucose alkaline fuel cell (DGAFC), which exhibited high catalytic activity towards glucose oxidation reaction. Maximum power density of 35.91 W m⁻² was achieved in the DGAFC equipped with a FeCo₂O₄ modified activated carbon (AC) anode, which was almost 151% higher than the control. Physical and electrochemical characterizations were performed to provide further understanding of the origin of its high activity. Our results show that the introduction of FeCo₂O₄ into the AC anode remarkably increase the exchange current density and reduce the charge transfer resistance. It is supposed that there is a synergistic effect between Fe (III) and Co (III), which accelerates electron transfer from glucose to external circuits. This study will promote the development of cost effective and environmentally benign catalysts for electrochemical energy applications.     

十二烷基硫酸钠修饰NiFe2O4对亚甲基蓝的类芬顿催化氧化性能

采用化学沉淀法制备了十二烷基硫酸钠（SDS）改性的纳米酸镍（记为NiFe₂O₄-S）,利用X射线衍射（XRD）、红外光谱（FTIR）、能谱（EDS）、透射电镜（TEM）、BET比表面等技术手段对样品进行了表征。采用多相芬顿氧化技术,以亚甲基蓝溶液为模拟污染物废水,研究了SDS对铁酸镍的改性效果、亚甲基蓝溶液初始pH以及催化剂循环使用等不同条件因素对样品类芬顿催化活性的影响。结果显示,经SDS改性后的NiFe₂O₄-S比纯相NiFe₂O₄表现出了更优异的催化性能,NiFe₂O₄-S对酸性（pH=3.5）、近中性（pH=6.5）和碱性（pH=9.5）的亚甲基蓝溶液均有着较好的催化降解效果;NiFe₂O₄-S具有良好的催化稳定性和重复使用性。对该催化反应体系的作用机理进行了详细探讨,NiFe₂O₄-S表现出优异的类芬顿催化活性归因于更强的电子转移能力,吸附的SDS能促进H₂O₂和 \text{?} {\mathrm{O}}_{\mathrm{2}}^{\text{-}} 分别与表面Fe³⁺反应将其还原转化为Fe²⁺。·OH是直接分解亚甲基蓝的活性物种,反应中NiFe₂O₄-S表面较高浓度的Fe²⁺可以有效地把H₂O₂分解为·OH。SDS增强了催化剂表面对亚甲基蓝的吸附能力,促进了·OH与亚甲基蓝的分解反应。     

超声波-微波协同辅助提取碱蓬多糖及抗氧化性分析

以盐地碱蓬为原料,采用超声波-微波协同法提取盐地碱蓬茎叶中多糖,对多糖的提取工艺进行分析优化,并对其抗氧化性进行分析。通过响应面法优化盐地碱蓬茎叶中多糖的最佳提取工艺为:料液比0.51 ∶ 80(g/mL)、超声功率366 W、提取时间21 min、提取温度70℃。在此条件下多糖得率为(10.714±0.720)%。体外试验表明,盐地碱蓬多糖对羟基自由基、DPPH·和O2-·均有明显的清除作用,多糖浓度5.1 mg/mL时,对羟基自由基、DPPH·和O2-·的清除率分别为89.2%、81.9%、79.2%,说明所提取的盐地碱蓬多糖具有较好的抗氧化活性。     

Ternary metal sulfides MoCoNiS derived from metal organic frameworks for efficient oxygen evolution

Developing a highly active and low-cost non-precious metal electrocatalyst for oxygen evolution has been urgent for the clean energy system. Herein, the ternary metal sulfides MoCoNiS supported on nickel foam (MoCoNiS/NF) are successfully prepared using Mo doping Co-based metal-organic framework (Co-MOF) as precursor, which may be helpful for the good dispersion of different metal element. The uniform elements distribution of Mo, Co and Ni on MoCoNiS/NF is determined by all kinds of physical characterization. Mo doping may regulate the electronic environment around Co and Ni, suggesting the potential synergistic effects between different heteroatoms. Electrochemical test shows that MoCoNiS/NF exhibits the excellent OER activity than other single metal or binary metal sulfides as comparison samples, needing only 151 and 226 mV overpotential to achieve current density of 10 (η₁₀ = 151 mV) and 100 mA cm⁻² (η₁₀₀ = 226 mV), respectively. The excellent stability of MoCoNiS/NF has been achieved. The remarkable OER performance of MoCoNiS/NF may due to the synergistic effects and good electrical conductivity as well as the three-dimensional structure of NF as substrate. Therefore, the rational design of MOF derived multi transition metal-based electrocatalysts will be an effective way for increasing OER performance.     

碱蓬植物盐提取工艺优化及其矿物质元素测定

目的 优化碱蓬植物盐提取工艺,测定碱蓬植物盐矿物质元素和重金属元素含量。方法 采用超声-微波协同提取法,以碱蓬植物盐得率为指标,通过单因素和响应面实验设计优化提取工艺参数。采用原子吸收光谱法和原子荧光光谱法测定碱蓬植物盐中元素含量。结果 优化的工艺参数为微波功率205 W、微波功率126 W、提取时间9 min、液料比82 mL:g,植物盐平均得率为31.50%±1.92%。不同生长阶段的碱蓬植物盐中,矿物质元素含量均呈现Na＞K＞Mg＞Ca＞Fe＞Cu＞Se的趋势,重金属元素Pb、Hg含量低于GB 2762-2021要求,未检测出As、Cd元素。结论 优化的工艺能够有效指导碱蓬植物盐的提取,碱蓬植物盐低钠高钾,富含多种营养元素,作为营养保健盐具有一定推广价值。     

Fabrication and characterization of TiO2/short MWNTs with enhanced photocatalytic activity

TiO₂/short MWNTs nanocomposites were prepared by the sol–gel method using butyl titanate and short MWNTs as starting materials in the solvent of isopropyl alcohol. Their photocatalytic activity in the degradation of X-3B was studied. The effects of mass ratio of short MWNTs to butyl titanate, and heat-treatment temperature on the photoactivity of TiO₂/short MWNTs nanocomposites were discussed. For comparison purpose, other photocatalysts were also employed in the photodegradation experiment. Thermogravimetric–differential thermal analysis (TG–DTA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV–Vis absorption spectra were utilized to characterize the prepared photocatalysts. The results showed that the TiO₂/short MWNTs nanocomposites synthesized with 1% mass ratio of short MWNTs to butyl titanate had the best photoactivity.     

Microstructure evolution and bonding mechanisms of silica sol bonded coating at elevated temperatures

High emissivity coating plays a critical role in thermal protective system, which can radiate a large amount of aero-convective heat. Silica sol bonded MoSi₂-SiC-Al₂O₃ (S-MSA) coating was proved to be promising for mullite fibrous insulation. However, the bonding mechanisms of the coating at elevated temperatures are not clear. In this work, the S-MSA coatings were heat-treated at temperatures from 600 °C to 1500 °C to reveal the bonding mechanisms at elevated temperatures. The S-MSA coatings go through a relatively stable stage (600 °C–1000 °C), a crystallization stage (1100 °C–1200 °C), and a densification stage (1300 °C–1500 °C) at ever increasing temperatures. Results show that both the contact damage resistance and the bonding strength of the calcined coatings exhibit a decrease followed by an increase at elevated calcination temperatures, with the inflection point at 1200 °C, corresponding to the transition temperature of the bonding mechanisms from 600 °C to 1500 °C.     

The influence of temperature on the solubility limit of Ca in alumina

Dopants and impurities can adsorb to surfaces and grain boundaries in ceramics, influencing the sintering kinetics and grain boundary mobility during processing. Ca is a common impurity in alumina that promotes grain growth at concentrations below the solubility limit, in contrast to the commonly observed solute-drag effect. Knowledge of the Ca solubility limit at temperatures relevant to processing is important to control microstructural evolution. Here we report on the experimentally measured solubility limit of Ca in α-alumina at 1400 °C and 1500 °C from equilibrated and quenched samples using standardized wavelength dispersive spectroscopy to be 32 ± 3 ppm and 45 ± 3 ppm, respectively. Together with the previously measured Ca solubility limit at 1600 °C, the enthalpy (0.95 eV per Ca) and vibrational entropy (-7.35 × 10⁻⁴ eV K^-1 per Ca) of solution were determined. A negative vibrational entropy of solution indicates coulombic interactions between the Ca cations and charge compensating defects in α-alumina.     

25％吡蚜酮·噻虫嗪水分散粒剂高效液相色谱分析

[目的]建立了一种高效液相色谱法测定25%吡蚜酮·噻虫嗪水分散粒剂中有效成分含量的方法。[方法]以Synergi 4μm Polar-RP80魡不锈钢柱为色谱柱,乙腈-水(体积比40:60)为流动相,在270 nm紫外检测波长下,对吡蚜酮和噻虫嗪进行分离和定量分析。[结果]吡蚜酮和噻虫嗪的保留时间分别为3.29、4.85 min,线性相关性分别为0.9995和0.9993,变异系数分别为1.13%和1.05%,平均加标回收率分别为103.1%和97.05%。[结论]方法简单,检测快速,结果准确,可满足日常定量分析的需要。     

壳聚糖基壁材在精油/鱼油微胶囊化方面的应用进展

微胶囊化可以提高精油/鱼油的抗氧化性、储存稳定性和生物活性以及改善其气味。具有良好生物相容性、成膜性和渗透性的壳聚糖及其衍生物成为制备微胶囊的理想壁材。本文以壳聚糖基壁材为主线,结合不同成囊机理和方法对精油/鱼油微胶囊制备研究进展进行综述。重点介绍了不同种类壳聚糖壁材（普通壳聚糖、壳聚糖复合物及壳聚糖衍生物）和成囊方法（如喷雾干燥法、单凝聚法、复凝聚法、交联法以及层层自组装法等）的优缺点。分析表明,改进成囊方法控制粒径和提高油包埋率;探寻无毒、高效的囊膜交联剂控制释放效率;合成新型的壳聚糖衍生物壁材提高功能性质,是壳聚糖基壁材包囊精油/鱼油的重要研究方向。