High lithium storage of Co3O4 enabled by integrating hollow and porous carbon scaffolds

The Co₃O₄, as a potential anode of lithium-ion batteries, has gained considerable attention because of high theoretical capacity. However, the Co₃O₄ is suffering from serious structure deterioration and rapid capacity fading due to its bulky volume change during cyclic charge/discharge process. Herein, to stabilize the lithium storage performance of the Co₃O₄ nanoparticles, a characteristic carbon scaffold (HPC) integrating hollow and porous structures has been fabricated by a well-designed method for the first time. The ultrafine Co₃O₄ nanoparticles are cleverly anchored on the HPC (HPC@Co₃O₄) and hence achieve significantly improved electrochemical properties including high capacity, improved reaction kinetics and outstanding cycle stability, showing high capacity of 1084.7 mAh g^-1 after 200 cycles at 200 mA g^-1 as well as 681.4 mAh g^-1 after 300 cycles at 1000 mA g^-1. The HPC@Co₃O₄ therefore shows good promising for application in advanced lithium-ion battery anodes. The results of the systematically material and electrochemical characterizations indicate that the synergistic effects of ultrafine Co₃O₄ nanoparticles and well-designed HPC scaffolds are responsible for the outstand performance of the HPC@Co₃O₄ anode. Moreover, this work can enrich the understanding and development of stable and high-performance metal oxide-based lithium-ion battery anodes for advanced lithium storage.     

Cubic B-splines method for Hall and ion slip impacts on unsteady MHD rotating flow past a vertical moving porous plate

The heat and mass transfer of unsteady magnetohydrodynamic (MHD) flow of Newtonian fluid with Hall current and ion-slip currents due to vast possible engineering applications is very important in areas like power generators, MHD accelerators, refrigeration coils, electric transformers, and heating elements. A quality-based research on Hall and ion-slip consequences on the rotating unsteady MHD flow past an infinite perpendicular moving absorbent plate have not been performed. Therefore, the Hall and ion-slip consequences on rotating unsteady MHD flow past an infinite perpendicular moving absorbent plate have not been performed. The similarity transformations are engaged to transfer the governing partial differential equations within favor of the scheme of nonlinear ordinary differential equations and elucidated numerically making use of cubic B-splines collocation mechanism. The influences of felicitous parameters on basic equations are remarked on through graphical profiles. Even though the computational estimations of frictional forces, Nusselt number, and Sherwood number for various parameters are distributed in tabular format and exchanged of views comparatively.     

“灰绿”协同措施对银川市合流制溢流污染的影响EI北大核心CSCD

针对合流制管网系统在雨天溢流污染严重,造成城市水体黑臭现象的问题,以银川市某高密度城区合流制管网系统为例,基于SWMM模型,在短历时设计降雨和长历时设计降雨两种条件下,模拟分析了合流制溢流(CSO)调蓄池、雨污管道混错接改造、绿化带海绵化改造等“灰绿”协同措施对CSO污染的影响。结果表明:CSO调蓄池、雨污管道混错接改造、绿化带海绵化改造及“灰绿”措施结合4种方案在短历时、长历时设计降雨条件下,随着降水量的增加,溢流水量及溢流污染物负荷均增加,溢流削减率均逐渐减小,其中“灰绿”措施结合方案对溢流污染的削减效果最为显著;重现期小于5 a时,溢流水量削减率与溢流污染物负荷削减率基本达到80%;降雨条件为中雨时,污染物负荷削减率基本达到75%;重现期为20 a时,溢流水量削减率及TSS、COD、TP、NH^(+)_(4)-N负荷削减率分别达到64%、70%、70%、70%、70%;降雨条件为大雨时,溢流水量削减率及TSS、COD、TP、NH^(+)_(4)-N负荷削减率分别达到28%、32%、26%、31%、33%。     

Cu-template-dependent synthesis of PtCu nanotubes for oxygen reduction reactions

The development of electrocatalysts with high activity and durability for oxygen reduction reaction (ORR) in acidic electrolyte environments remains a serious challenge for clean and efficient energy conversion. Synergistic effects between Pt and inexpensive metals, the d band center of Pt and catalyst morphology could adjust the adsorption and desorption of oxygen intermediates by the Pt. All the factors affect the catalytic performance of Pt-based nanocrystals. Here, we prepared Cu@PtCu₃ NWs with an average diameter of 74.9 nm for Cu and about 10 nm PtCu₃ layer. After etching, the Cu@PtCu₃ nanowires is transformed into PtCu nanotube structure, due to the removal of copper from the surface and interior. PtCu NTs for ORR shows excellent activities and durability due to the integration of structural advantages and synergistic effects. Notably, the mass activity and specific activity of PtCu NTs (0.105 A mg^?1_Pt and 0.230 mA cm^?2_Pt) are 2.0 and 3.8 times higher than that of commercial Pt/C (0.053 A mg^?1_Pt and 0.06 mA cm^?2_Pt). The etching process to change the morphology of the catalyst and alter the electronic structure of the catalyst is expected to be useful for the design of future structured Pt-based alloy nanocatalysts.     

Surface Reconstruction Engineering with Synergistic Effect of Mixed-Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells

Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI₂. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions.     

菌酶协同改善花生粕的饲用品质

花生粕是重要的蛋白饲料原料，但由于其氨基酸不平衡，特别是精氨酸与赖氨酸比例严重失衡（精氨酸与赖氨酸含量比值在3~4，理想的精氨酸与赖氨酸含量比值为1.0），限制了其在动物养殖中的应用。研究了复合酶预处理结合乳酸菌发酵花生粕对其品质的改善。结果表明：经菌酶协同处理后，花生粕粗蛋白质含量由46.4%提高至506%，大分子蛋白明显降解为小分子蛋白，酸溶蛋白质含量由2.3%提高至17.8%，多肽含量由1.6%提高至15.7%，蛋氨酸和赖氨酸含量分别提高了77.1%和42.0%，精氨酸降解率为18.7%，精氨酸与赖氨酸含量比值从3.7降低至2.1，总酸含量由06%提高到4.7%，其中乳酸含量由0.64 mg/g提高至14.63 mg/g。菌酶协同处理后的花生粕抗氧化性明显增强，其中每克菌酶协同处理后的花生粕对羟自由基的清除能力与171.6 mg VC相当，比花生粕（与47.6 mg VC相当）提高了2.6倍。     

Surface structure and quenching effects in BiFeO3-BaTiO3 ceramics

The structure and properties of Mn-doped 0.67BiFeO₃-0.33BaTiO₃ ceramics are systematically investigated with respect to the effects of annealing prior to rapid cooling by quenching in air. Air-quenching induces a change in crystal structure from pseudo-cubic to rhombohedral, with higher quenching temperatures leading to an increased rhombohedral distortion. These structural changes are correlated with the appearance of more well-defined ferroelectric domain configurations. It is shown that the surface preparation procedures for XRD measurements can induce significant changes in the peak profiles, indicating differences in crystal structure between the surface and bulk regions. Frequency dispersion in the temperature-dependent relative permittivity for the as-sintered sample is significantly reduced after quenching, accompanied by enhancement of the Curie point and improved temperature-stability of piezoelectric properties. It is proposed that the formation of defect clusters by A-site cation diffusion during cooling is circumvented by quenching, leading to the observed modification of structural distortion and ferroelectric properties.