摘要：The influence of the magnetism of transition metal oxide,nickel(II)oxide(NiO),on its surface reactivity and the dependence of surface reactivity on surface orientation and reactant magnetism were studied by density functional theory plus U *** considered five different antiferromagnetically ordered structures and one ferromagnetically ordered structure,NiO(001)and Ni(011)surfaces,paramagnetic molecule NO,and nonparamagnetic molecule *** calculations showed that the dependence of surface energies on magnetism was modest,ranging from49to54meV/?2for NiO(001)and from162to172meV/?2for NiO(011).On NiO(001),both molecules preferred the top site of the Ni cation exclusively for all NiO magnetic structures considered,and calculated adsorption energies ranged from?0.33to?0.37eV for CO and from?0.42to?0.46eV for *** NiO(011),both molecules preferred the bridge site of two Ni cations irrespective of the NiO *** was found that rather than the long‐range magnetism of bulk NiO,the local magnetic order of two coordinated Ni cations binding to the adsorbed molecule had a pronounced influence on *** calculated NO adsorption energy at the(↑↓)bridge sites ranged from?0.99to?1.05eV,and become stronger at the(↑↑)bridge sites with values of?1.21to?*** CO,although the calculated adsorption energies at the(↑↓)bridge sites(?0.73to?0.75eV)were very close to those at the(↑↑)bridge sites(?0.71to?0.72eV),their electron hybridizations were very *** present work highlights the importance of the local magnetic order of transition metal oxides on molecular adsorption at multi‐fold sites.

摘要：Ruthenium(Ru)serves as a promising catalyst for ammonia synthesis via the Haber-Bosch process,identification of the structure sensitivity to improve the activity of Ru is important but not fully explored *** present here density functional theory calculations combined with microkinetic simulations on nitrogen molecule activation,a crucial step in ammonia synthesis,over a variety of hexagonal close-packed(hcp)and face-center cubic(fcc)Ru ***{2130}facet exhibits the highest activity toward N_(2) dissociation in hcp Ru,followed by the(0001)monatomic step *** other hcp Ru facets have N_(2) dissociation rates at least three orders ***{211}facet shows the best performance for N_(2) activation in fcc Ru,followed by{311},which indicates stepped surfaces make great contributions to the overall *** hcp Ru{2130}facet and(0001)monatomic step sites have lower or comparable activation barriers compared with fcc Ru{211}facet,fcc Ru is proposed to be more active than hcp Ru for N_(2) conversion due to the exposure of the more favorable active sites over step surfaces in fcc *** work provides new insights into the crystal structure sensitivity of N_(2) activation for mechanistic understanding and rational design of ammonia synthesis over Ru catalysts.

摘要：氢气活化在过渡金属氧化物催化的加氢反应中起到至关重要的作用.二氧化铈(CeO_(2))表面上氢气如何活化是乙炔加氢反应中的重要科学问题.本文利用密度泛函理论计算(DFT)的方法,系统研究了化学计量及有氧缺陷的CeO_(2)(111)、(110)和(100)表面上氢气活化机理.氢气在化学计量的CeO_(2)表面解离时仅形成羟基,而氧空位的存在可以有效促进氢气活化.CeO_(2-x)(111)和(100)缺陷表面上H^(+)和H^(-)物种可以共存,而在CeO_(2-x)(110)缺陷表面上只能观察到H^(+)物种.化学计量及有氧缺陷的CeO_(2)表面上氢气活化的结构敏感性与H^(+)和H^(-)吸附能有关,并由氧空位形成能以及Ce、O离子的电荷分布决定.该理论工作深入理解了二氧化铈基催化剂上氢气活化过程,为优化和设计高效加氢催化剂提供了理论支撑.

摘要：Metal–organic framework(MOF)membranes hold great promise in energy-efficient chemical *** outstanding challenges of the microstructural design stem from(1)thinning of membranes to immensely reduce the mass-transfer resistance(for high permeances);(2)tuning of orientation to optimize the selective transport of gas molecules,and(3)reinforcement of intercrystalline structure to subside leakage through defective gaps(for high selectivity).Here,we propose the ZIF-L membrane that is completely confined into the voids of the alumina support through an interfacial assembly process,producing an appealing membrane-interlocked-support(MIS)composite architecture that meets the requirements of the microstructural design of MOF ***,the membranes show average H2 permeances of above 4000 GPU and H_(2)/CO_(2) separation factor(SF)of above 200,representing record-high separation performances of ZIF-L membranes and falling into the industrial target zone(H_(2) permeance>1000 GPU and H_(2)/CO_(2) SF>60).Furthermore,the ZIF-L membrane possessing the MIS composite architecture that is established with alumina particles as scaffolds shows mechanical stability,scraped repeatedly by a piece of silicon rubber causing no selectivity loss.

摘要：合金材料因其丰富可调的几何结构和电子性质,在催化和材料科学领域得到了广泛的应用.其中合金形成能作为一个重要的物理量,对合金材料的形成和催化活性有重要影响.近年来,随着人工智能和数据库的发展,利用机器学习的方法研究和设计新的材料成为新的研究焦点.基于此,通过人工智能的多任务压缩感知算法,结合AB2合金形成能数据库展开了合金形成能描述符和预测研究.首先建立了相应合金形成能的通用描述符,并展开了特征敏感性分析,揭示出合金材料组分的电子性质和几何性质的影响及其相互依赖关系.研究结果显示,该描述符的预测误差低于8.10 kJ·mol^(-1),具有清晰的物理可阐述性,并预测了大量未知合金材料的形成能.

摘要：设计合成了具有精确分子结构的聚合物对深入了解其结构与性能之间的关系起着至关重要的作用。研究了一种合成带有三乙基硅氧侧基的环状无规共聚酯的新方法。功能性单体γ-三乙基硅氧基-ε-己内酯(γ-Et3SiOεCL)和ε-己内酯(ε-CL)在环状引发剂2,2-二丁基-2-锡-1,3-二氧环庚烷(DSDOP)的作用下,进行活性开环聚合反应以制备活性环状无规共聚酯(LCP(εCLcoγEt3SiOεCL))前体,当单体完全转化后,以该活性环状前体作为大分子引发剂,引发反应性单体α-(1-丙烯酰氧乙基)-ε-己内酯(αAEεCL)进行嵌段聚合反应,合成了在活性中心附近带有不饱和双键的功能性环状嵌段共聚酯,即活性环状聚(ε-己内酯-co-γ-三乙基硅氧基-ε-己内酯)-b-(α-(1-丙烯酰氧乙基)-ε-己内酯)。最后该活性环状嵌段共聚酯在紫外光照射下,反应性单体结构单元中的双键发生分子内交联反应,从而制得稳定的不含有机锡的新型环状无规共聚酯cP(εCLcoγEt3SiOεCL)(Mn,NMR=28500)。采用SEC、1H NMR以及DSC等技术手段对聚合物的结构和性能进行表征。该方法的突出特点是能够高效地合成带有功能性侧基的高相对分子质量的环状无规共聚酯。

摘要：在许多能源相关的化学过程中,化学反应是在具有催化功能的界面或者团簇分子表面上发生的。要弄清团簇和催化表面的反应机理,在原子分子层次上研究团簇以及表面相关的化学反应过程是非常必要的。该研究目标是建立质谱与红外光解离光谱以及光电子能谱相结合的实验研究方法,通过对选质量金属及金属氧化物等团簇的气相反应动力学研究,获得团簇反应的尺寸效应、价态、几何和电子结构等对反应活性和机理的影响,阐明团簇反应的机理和规律;发展和利用表面光电子能谱和光电子显微镜技术,结合第一性理论计算方法和分子动力学模拟等理论方法,通过对金属氧化物表面的几何结构和电子结构以及表面团簇反应的研究,获得表面反应的机理和动力学。该研究选质量过渡金属氧化物团簇的光谱和结构研究。利用质谱、红外光解离光谱等实验方法获得选质量团簇的振动光谱等信息,结合理论计算,获得团簇的结构和成键特性。设计并建立基于质谱和红外光解离光谱联用技术的选质量团簇与小分子反应的实验装置。通过对不同大小的金属氧化物团簇的研究,获得团簇尺寸对其结构、稳定性和成键特性的影响等。在表面反应动力学实验研究方面,开展了氧化物/金属反转催化体系表面结构及反应的动态研究。