调控磁导率以优化高熵合金的自旋电子排列实现高效析氧反应

磁场触发的催化剂轨道电子自旋排列已成为促进析氧反应的一种有趣而可行的策略.然而,具有强d-d库仑相互作用的高熵合金(HEAs)催化剂中的磁场增强机制尚未得到充分挖掘.在此,我们设计了具有优异软磁性的高熵合金金属片,在微小磁场下表现出显著的磁场增强催化作用,其磁导率可作为评估磁场增强的描述因子.具体地,仅施加50 mT的磁场,(FeCoNi)_(82.5)Cr_(17.5)HEAs的过电位下降就超过了36mV@10 mA cm^(-2).此外,过电位的降低与HEA的磁导率呈线性关系.原位拉曼光谱与理论计算结果表明,施加磁场可显著提高自旋密度,改善催化剂的3d电子与*O自由基的2p轨道之间的自旋相互作用,从而有效降低速率决定步骤(*O→*OOH)的能量障碍,进而促进O-O的形成.

Enhancing production of a 24-membered ring macrolide compound by a marine bacterium using response surface methodology

A 24-membered ring macrolide compound,macrolactin A has potential applications in pharmaceuticals for its anti-infectious and antiviral activity.In this study,macrolactin A was produced by a marine bacterium,which was identified as Bacillus subtilis by 16S ribosomal RNA(rRNA) sequence analysis.Electrospray ionization mass spectrometry(ESI/MS) and nuclear magnetic resonance(NMR) spectroscopy analyses were used to characterize this compound.To improve the production,response surface methodology(RSM) involving Box-Behnken design(BBD) was employed.Faeces bombycis,the main by-product in sericulture,was used as a nitrogen source in fermentation.The interactions between three significant factors,F.bombycis,soluble starch,and(NH4)2SO4 were investigated.A quadratic model was constructed to fit the production and the factors.Optimum medium composition was obtained by analysis of the model.When cultivated in the optimum medium,the production of macrolactin A was increased to 851 mg/L,2.7 times as compared to the original.This study is also useful to find another way in utilizing F.bombycis.

Recent Advances for the Synthesis and Applications of 2-Dimensional Ternary Layered Materials

Layered materials with unique structures and symmetries have attracted tremendous interest for constructing 2-dimensional(2D)structures.The weak interlayer interaction renders them to be readily isolated into various ultrathin nanosheets with exotic properties and diverse applications.In order to enrich the library of 2D materials,extensive progress has been made in the field of ternary layered materials.Consequently,many brand-new materials are derived,which greatly extend the members of 2D realm.In this review,we emphasize the recent progress made in synthesis and exploration of ternary layered materials.We first classify them in terms of stoichiometric ratio and summarize their difference in interlayer interaction,which is of great importance to produce corresponding 2D materials.The compositional and structural characteristics of resultant 2D ternary materials are then discussed so as to realize desired structures and properties.As a new family of 2D materials,we overview the layer-dependent properties and related applications in the fields of electronics,optoelectronics,and energy storage and conversion.The review finally provides a perspective for this rapidly developing field.