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Ultrafine SnPd Nanoalloys Promise High-Efficiency Electrocatalysis for Ethanol Oxidation and Oxygen Reduction
No full textThe catalytic activity and stability of palladium (Pd)-based electrocatalysts for ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) can be improved by optimizing their composition and structure. Alloying tin (Sn) into Pd can induce electronic and synergistic effects, which weaken the adsorption of intermediate species (e.g., O and OH in ORR and CO in EOR) on Pd sites and even promote their further transformation. However, the SnPd alloys often suffer from complicated synthesis, large particle size, and inhomogeneity. In this context, we report the synthesis of SnPd nanoalloys with an ultrafine size of ca. 3.8 nm using a simple one-pot approach and their superior catalytic performance for EOR and ORR. Specifically, the SnPd alloy nanoparticles with an optimized Sn/Pd ratio of 18/82 show the mass and specific activity of 3.8 A mg-1 and 5.72 mA cm-2, respectively, for EOR, while excellent performance for ORR with a half-wave potential of 0.92 V and specific activity of 3.46 mA cm-2 at 0.9 V, both of which are much higher than those of their commercial Pd/C and Pt/C counterparts
(NH_4)_2SO_4和Na_2SO_4混合溶液中(NH_4)_2SO_4结晶动力学及铁/铝/锰/铬等离子对(NH_4)_2SO_4结晶的影响规律
No full text湿法冶金、三元前体制备等过程均会产生含硫酸钠与硫酸铵的高盐废水。研究高盐废水中硫酸铵的结晶动力学,并考察常见金属离子的影响规律对高盐废水处理具有重要意义。本文以含硫酸钠与硫酸铵混合溶液中硫酸铵的结晶过程为例,系统考察了硫酸铵的结晶动力学及铁、铝、锰、铬对硫酸铵结晶的影响规律。含硫酸钠与硫酸铵混合溶液硫酸铵结晶动力学研究结果表明,硫酸铵生长速率和成核速率方程分别为为B = 1.303 × 10~(-16)G1.069MT1.801,G = 15.708σ1.387;在硫酸钠与硫酸铵混合体系中,溶液过饱和度影响硫酸铵成核及生长速率,溶液过饱和度减小,晶体的成核及生长速率都会减小,与单体系硫酸铵结晶动力学结果相比,动力学参数均有所下降。铁、铝、锰、铬对硫酸铵结晶的影响规律研究结果表明,铁、铝抑制了硫酸铵晶面生长,结晶粒度减小;锰、铬对硫酸铵结晶有一定的促进作用,结晶粒度增大。金属离子改变了硫酸铵晶习,锰使结晶呈现三棱柱状,铁、铝使硫酸铵结晶片状生长。不同金属离子条件下的结晶动力学方程表明,铁和铝对结晶成核过程作用更为显著,锰和铬可以促进硫酸铵生长过程。</p
颗粒级配对锂浆料电池性能的影响
No full text利用大小颗粒之间的填充效应,本文设计了2种粒径的活性颗粒组成7种级配体系,并系统研究了其浆料的性能。借助激光粒度仪、电导率仪、比表面测试仪、扫描电子显微镜、沉降测试和电化学测试等手段分析了样品粒度分布、比表面积、颗粒形貌、浆料的电导率、沉降率、电化学阻抗谱和充放电性能。结果表明,所有级配粒径分布均呈单峰接近正态分布;级配颗粒属于大孔或者无孔材料;小颗粒是典型的单晶结构,大颗粒由球形大颗粒构成,3∶7和0∶10样品扫描电子显微镜图显示大粒径周围被小粒径和导电剂包围着,形成了完整连续的三维导电网络;大颗粒组成的浆料电导率为41.80 mS/cm,小颗粒组成的浆料电导率高达123.39 mS/cm; 3∶7样品浆料的沉降率和沉降速率最小,颗粒级配更接近Fuller最密充填粒度分布经验曲线;3∶7和5∶5样品0.1 C的放电比容量分别达到194.88 mAh/g和187.38 mAh/g,实际比容量发挥分别高于商业典型值10%、5%以上,首次充放电效率高达90.54%、87.96%。此外,3∶7样品电池还表现出最优异的循环性能,经循环250次后,容量保持率为83.63%。总之,级配为3∶7样品的颗粒填充效应得到充分发挥,表现出最优异的性能。本文提供了最佳比例的颗粒级配设计比,为优异性能的颗粒级配提供重要参考
废弃SCR催化剂氧化酸洗除As工艺及机理研究
No full text砷(As)及其他杂质元素是导致燃煤电厂废弃SCR脱硝催化剂失活的主要原因,借助Fenton反应对废弃SCR脱硝催化剂中的有害杂质元素As及Fe、Al进行氧化酸洗脱除,探究了酸洗液种类、酸浓度、氧化剂浓度、反应温度、反应时间、液固比等因素对杂质浸出率的影响。结果表明,最佳的杂质浸出条件为:反应温度为50℃、H_2SO_4浓度为1.5 mol/L、H_2O_2浓度为1.5 mol/L、转速为500 r/min、反应时间为240 min、液固比为20 mL/g,此时As、Fe、Al的浸出率分别为99.58%、41.80%、 39.60%。废弃催化剂杂质元素浸出机理为过氧化氢与被硫酸浸出的Fe~(2+)形成了芬顿试剂,将As~(3+)氧化为As~(5+),使其氧化溶出,提高了As元素的脱除效率
Hollow Nanomaterials in Advanced Drug Delivery Systems: From Single- to Multiple Shells
No full textHollow-structured nanomaterials (HSNMs) have attracted increased interest in biomedical fields, owing to their excellent potential as drug delivery systems (DDSs) for clinical applications. Among HSNMs, hollow multi-shelled structures (HoMSs) exhibit properties such as high loading capacity, sequential drug release, and multi-functionalized modification and represent a new class of nanoplatforms for clinical applications. The remarkable properties of HoMS-based DDS can simultaneously satisfy and enhance DDSs for delivering small molecular drugs (e.g., antibiotics, chemotherapy drugs, and imaging agents) and macromolecular drugs (e.g., protein/peptide- and nucleic acid-based drugs). First, the latest research advances in delivering small molecular drugs are summarized and highlight the inherent advantages of HoMS-based DDSs for small molecular drug targeting, combining continuous therapeutic drug delivery and theranostics to optimize the clinical benefit. Meanwhile, the macromolecular drugs DDSs are in the initial development stage and currently offer limited delivery modes. There is a growing need to analyze the deficiency of other HSNMs and integrate the advantages of HSNMs, providing solutions for the safe, stable, and cascade delivery of macromolecular drugs to meet vast treatment requirements. Therefore, the latest advances in HoMS-based DDSs are comprehensively reviewed, mainly focusing on the characteristics, research progress by drug category, and future research prospects
DDPM simulation of the erosion of immersed tubes in a pulsating fluidized bed
No full textIn this study, the effects of the type of pulsating inlet waveform, pulsation frequency, and pulsation amplitude on the stability of fluidized beds and the erosion of immersed tubes were investigated by numerical simulation. Compared with rectangular and triangular inlet flows, sinusoidal flow induced the lowest immersed-tube erosion rate and pressure-drop fluctuation in the fluidized bed. Furthermore, under sinusoidal flow with a pulsation frequency of 1 Hz and pulsation amplitude of 0.25um, the immersed-tube erosion rate was lower by 1.8 %, standard deviation of pressure drop by 14.16 %, and energy generated from bubble rupture by 47.83 % than those under uniform flow. A dimen-sionless parameter vp that can represent immersed-tube erosion during pulsating flow was proposed, which reflects the effect of particle flow characteristics, particle fluidization degree, and pulsation fre-quency on immersed-tube erosion.CO 2023 Elsevier Ltd. All rights reserved