亲锂电解液在LiNi0.6Mn0.2Co0.2O2／Li二次锂金属电池中的电化学性能

金属锂电池被认为是具有良好前景的下一代高能量密度电池。然而,传统的碳酸酯类电解液与锂的亲和性差,在循环过程中由于锂枝晶的生长和固体电解质膜（SEI）的不稳定导致金属锂电池性能快速衰减。采用1.2 mol／L六氟磷酸锂（LiPF₆）／二氟草酸硼酸锂（LiDFOB）／氟代碳酸乙烯酯（FEC）／碳酸二乙酯（DEC）,并添加了双三氟甲磺酰亚胺锂（LiTFSI）作为电解液,对其在LiNi_0.6Mn_0.2Co_0.2O₂／40 μm-Li（单位面积上负／正极材料的实际容量的比N／P＝2.85）电池中的电化学性能进行了研究。LiNi_0.6Mn_0.2Co_0.2O₂／40 μm-Li电池表现出优异的循环稳定性（循环120圈后,容量保持率>93%）和倍率性能（3C倍率下放电比容量为110 mA·h／g）。良好的电化学性能主要归因于该电解液可以在金属锂表面形成致密且稳定的SEI,并抑制锂枝晶的产生。     

Approaches to achieve surface sensitivity in the in situ XAS of electrocatalysts

In situ and operando techniques providing information regarding adsorbate bonding and atomic arrangements on the electrode surface along with pure electrochemical measurements are needed to more fully understand the detailed mechanism of electrocatalytic reactions on high surface areas/nanoparticle electrocatalysts. X-ray adsorption spectroscopy (XAS) is a powerful tool to interrogate the electronic structure and local coordination environment of such electrocatalysts under working conditions, but it should be acknowledged that standard XAS methods are not intrinsically surface sensitive. This review will present recent in situ XAS studies on single-atom, metal, and metal oxide electrocatalysts, highlighting the approaches taken to achieve surface sensitivity by careful designing of the sample under investigation.     

A Highly Sensitive and Selective Non-enzymatic Hydrogen Peroxide Sensor Based on Nanostructured Co3O4 Thin Films Using the Sol-gel Method

In this work we report an easy and efficient way to fabricate nanostructured cobalt oxide (Co₃O₄) thin films as a non-enzymatic sensor for H₂O₂ detection. Co₃O₄ thin films were grown on ITO glass substrates via the sol-gel method and characterized with several techniques including X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and optical absorbance. The Co₃O₄ thin films’ performance regarding hydrogen peroxide detection was studied in a 0.1 M NaOH solution using two techniques, cyclic voltammetry (CV) and amperometry. The films exhibited a high sensitivity of 1450 μA.mM⁻¹.cm⁻², a wide linear range from 0.05 μM to 1.1 mM, and a very low detection limit of 18 nM. Likewise, the Co₃O₄ thin films produced showed an exceptional stability and a high selectivity.     

An evaluation method for nanoscale wrinkle

In this paper, a spectrum-based wrinkling analysis method via two-dimensional Fourier transformation is proposed aiming to solve the difficulty of nanoscale wrinkle evaluation. It evaluates the wrinkle characteristics including wrinkling wavelength and direction simply using a single wrinkling image. Based on this method, the evaluation results of nanoscale wrinkle characteristics show agreement with the open experimental results within an error of 6%. It is also verified to be appropriate for the macro wrinkle evaluation without scale limitations. The spectrum-based wrinkling analysis is an effective method for nanoscale evaluation, which contributes to reveal the mechanism of nanoscale wrinkling.     

Impact of thermal annealing on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

A study on impact of post-deposition thermal annealing on the physical properties of CdTe thin films is undertaken in this paper. The thin films of thickness 500 nm were grown on ITO and glass substrates employing thermal vacuum evaporation followed by post-deposition thermal annealing in air atmosphere within low temperature range 150–350 °C. These films were subjected to the XRD, UV‐Vis NIR spectrophotometer, source meter, SEM coupled with EDS and AFM for structural, optical, electrical and surface topographical analysis respectively. The diffraction patterns reveal that the films are having zinc-blende cubic structure with preferred orientation along (111) and polycrystalline in nature. The crystallographic parameters are calculated and discussed in detail. The optical band gap is found in the range 1.48–1.64 eV and observed to decrease with thermal annealing. The current–voltage characteristics show that the CdTe films exhibit linear ohmic behavior. The SEM studies show that the as-grown films are homogeneous, uniform and free from defects. The AFM studies reveal that the surface roughness of films is observed to increase with annealing. The experimental results reveal that the thermal annealing has significant impact on the physical properties of CdTe thin films and may be used as absorber layer to the CdTe/CdS thin films solar cells.     

Crystalline orientation of BiMnO3 thin films grown by rf-sputtering

BiMnO₃ thin films were deposited by means of rf-sputtering onto [1 0 0] oriented SrTiO₃ substrates. X-ray diffraction measurements revealed epitaxial growth with [0 0 l]_m orientation in the monoclinic structure representation, equivalent to the direction of the pseudocubic cationic lattice. This [0 0 l]_m orientation was obtained in a wide deposition parameters range. Preliminary magnetization measurements suggest that these films do not present ferromagnetism below the bulk Curie temperature, T_C=105 K.     

Analytical analysis of anisotropic thermophoresis of a charged spheroidal colloid in aqueous media for extremely thin EDL cases

Thermophoresis of charged spheroids has been widely applied in biology and medical science. In this work, we report an analysis of the anisotropic thermophoresis of diluted spheroidal colloids in aqueous media for extremely thin EDL cases. Under the boundary layer approximation, we formulate the thermophoretic velocity, the thermophoretic force, and the thermodiffusion coefficient of a randomly dispersed spheroid. The parametric studies show that under the aforementioned conditions, the thermophoresis is anisotropic and its thermodiffusion coefficient should be considered as a vector, D _T. The thermodiffusion coefficient values and directions of D _T are strongly related to the aspect ratio and the angle θ between the externally applied temperature gradient and the particle's axis of revolution: The increasing aspect ratio enlarges the thermodiffusion coefficient value D_T of prolate (oblate) spheroids to a constant value when θ < 60° (θ > 45°), and it reduces D_T of prolate (oblate) spheroids to a constant value when θ > 60° (θ < 45°). The thermodiffusion coefficient direction of both prolate and oblate spheroids deviates slightly from −∇T_∞ for a small aspect ratio, and such deviation becomes serious for a large aspect ratio.     

甘油氧化的光谱电化学傅里叶变换衰减全反射谱红外光谱薄膜流动池中硼酸镍层厚度的优化

在碱性甘油电氧化反应中,利用电化学傅里叶变换衰减全反射谱红外光谱法,研究了薄膜流动池中滴注硼酸镍催化剂负载量对玻碳电极性能的影响.连续操作的径向流动池包括一个位于内反射元件上方50μm的钻孔电极,可实现红外光谱分析.这是在确定条件下对电催化剂进行简便和可重复筛选的一个适合的方法,同时还提供了对复杂反应(如甘油氧化)产物选择性的检测.通过对泵送电解液进行更耗时的定量高效液相色谱分析,结果表明,衰减全反射红外光谱法可快速鉴定产物.在层流条件下,水中使用0.1 M甘油和1 M KOH,流速为5μL min-1时,甘油转化率较高.转化率和选择性取决于催化剂的负载量,负载量又决定了催化剂层的厚度和粗糙度.由于在更粗糙的膜中停留时间更长有利于再吸附和C-C键断裂,因此当负载量最高达210μg cm-2时,甘油转化率为73％且甲酸选择性接近80％.当最低负载量为13μg cm-2时,甘油转化率达到63％,甲酸选择性降至60％,相应地,C2物种(如乙醇酸盐)选择性较高,为8％.因此,只有催化剂负载量较低时才能形成几微米厚度范围内的薄膜,此时才适合进行优质催化剂的筛选.     

Advanced Surfaces by Anchoring Thin Hydrogel Layers of Functional Polymers

Surface design and engineering is a critical tool to improve the interaction of materials with their surroundings. Immobilization of soft hydrogels is one of the attractive strategies to achieve surface modification. The goal of this review is to provide a comprehensive overview of the different strategies used for surface tethering of hydrogel layers via crosslinking immobilization of pre-fabricated functional polymers. In this strategy, crosslinkable polymers are first prepared via various polymerization techniques or post-functionalization of polymers. Afterwards, the crosslinkable polymers are attached or tethered on the surfaces of substrates using a variety of approaches including photo-crosslinking, click reactions, reversible linkages, etc. For each case, the principles of hydrogel tethering have been explained in detail with representative examples.Moreover, the potential applications of the as-modified substrates in specific cases have also been addressed and overviewed.     

Effect of Interfacial Adsorption on the Stability of Thin Polymer Films in a Solvent-induced Process

The stability of ultrathin polymer films plays a crucial role in their technological applications. Here, we systematically investigated the influence of interfacial adsorption in physical aging and the stability of thin polymer films in the solvent-induced process. We further identify the stability mechanism from the theory of thin film stability. Our results show that the aging temperature and film thickness can strongly influence the stability of thin PS films in acetone vapor. Physical aging can greatly improve the stability of thin polymer films when the aging temperature T_(aging1)T_g. A thinner PS film more quickly reaches a stable state via physical aging. At short aging time, the formation of the adsorbed layer can reduce the polar interaction; however, it slightly influences the stability of thin polymer films in the solvent-induced process. At later aging stage,the conformational rearrangement of the polymer chains induced by the interfacial effect at the aging temperature T_(aging1) plays an important role in stabilizing the thin polymer films. However, at T_(aging2)T_g, the process of physical aging slightly influences the stability of the thin polymer films.The formation of the adsorbed layer at T_(aging2) can reduce the short-range polar interaction of the thin film system and cannot suppress the instability of thin polymer films in the solvent-induced process. These results provide further insight into the stable mechanism of thin polymer films in the solvent-induced process.