轻质储氢材料改性与热力学调控进展

为解决环境与能源问题,氢能作为一种理想的二次能源,受到国内外研究者的关注.众多储氢方式中,固态储氢能量密度高、安全性好,被认为是最具有发展前景的储氢方式之一.由轻质元素组成的储氢材料(包含金属氢化物、硼氢化物、铝氢化物、氨基氢化物、氨硼烷)因其具有高的储能密度成为储氢领域的研究热点.本文从热力学角度出发,对几种轻质储氢材料的研究进展,尤其是材料的改性进行了总结,并对轻质储氢材料的发展趋势进行了展望.     

硼氢化锂储氢材料研究*

车载储氢是推进氢燃料车规模化商业应用的“瓶颈”环节,开发高性能车载储氢材料/技术成为当前能源及材料领域关注的热点。近年来,随着储氢材料领域的不断拓展,以硼氢化锂（LiBH₄）为典型代表的高储量配位金属氢化物日渐成为新兴的储氢材料研究热点。本文从体系成分/反应路径调整、纳米结构调制、阴/阳离子替代及催化体系构建等方面概述了改善LiBH4综合储/放氢性能的最新研究进展,旨在明确配位硼氢化物储氢材料研究中的关键问题及可能的解决途径。     

新型储氢材料及其热力学与动力学问题

氢能作为一种理想的二次能源受到了国内外科研工作者的广泛关注,研制可以在室温和较低压力下方便、安全、高效地储存氢能的材料是氢能发展的瓶颈.到目前为止,固态储氢材料以能量密度高及安全性好等优势被认为极具应用前景,其中以轻质元素构成的氢化物(包括硼氢化物/铝氢化物(可用通式A(MH4)n表示,其中A是碱金属(Li,Na,K)或碱土金属(Be,Mg,Ca);M是硼或铝;n=1～4)、氨基氢化物(如LiNH2等))、氨硼烷(NH3BH3)、金属有机骨架材料(MOFs)是新型储氢材料研究领域的热点,本文将着重就目前这几类储氢材料的研究当中所涉及到的一些热力学及动力学问题进行总结探讨.     

金属硼氢化物基固态储氢体系

氢气储存仍是制约氢经济推行的关键问题,开发一种高效、安全的储氢技术仍面临着巨大挑战。近年来,利用固态氢化物的化学吸附储氢技术由于可靠、结构紧密和高储氢容量的特点,被视为最有潜力的储氢手段之一。在众多固态氢化物储氢材料中,金属硼氢化物由于其极高的重量和体积储氢密度而备受关注。然而,金属硼氢化物热力学稳定,动力学缓慢,导致其吸/放氢温度高、速率慢、可逆性及循环稳定性差。本文从替代、复合、掺杂、纳米结构限域及相应的反应机理等角度总结了金属硼氢化物储氢材料的最新改性研究和应用,并提出了其中存在的问题和相应对策,同时指出了未来的研究方向。     

储氢研究进展

氢能是21世纪主要的新能源之一。作为一种新型的清洁能源,氢的廉价制取、安全高效储存与输送及规模应用是当今研究的重点课题,而氢的储存是氢能应用的关键。储氢材料能可逆地大量吸放氢,在氢的储存与输送过程中是一种重要载体。本文综述了目前所采用或正在研究的主要储氢材料与技术,如高压气态储氢、低温液态储氢、金属氢化物储氢、化学氢化物储氢、吸附储氢、金属有机骨架储氢等,比较了各种储氢的优缺点,并指出其相关发展趋势。     

储氢研究进展

氢能是21世纪主要的新能源之一。作为一种新型的清洁能源,氢的廉价制取、安全高效储存与输送及规模应用是当今研究的重点课题,而氢的储存是氢能应用的关键。储氢材料能可逆地大量吸放氢,在氢的储存与输送过程中是一种重要载体。本文综述了目前所采用或正在研究的主要储氢材料与技术,如高压气态储氢、低温液态储氢、金属氢化物储氢、化学氢化物储氢、吸附储氢、金属有机骨架储氢等,比较了各种储氢的优缺点,并指出其相关发展趋势。     

储氢研究进展

氢能是21世纪主要的新能源之一.作为一种新型的清洁能源,氢的廉价制取、安全高效储存与输送及规模应用是当今研究的重点课题,而氢的储存是氢能应用的关键.储氢材料能可逆地大量吸放氢,在氢的储存与输送过程中是一种重要载体.本文综述了目前所采用或正在研究的主要储氢材料与技术,如高压气态储氢、低温液态储氢、金属氢化物储氢、化学氢化物储氢、吸附储氢、金属有机骨架储氢等,比较了各种储氢的优缺点,并指出其相关发展趋势.     

纳米限域的储氢材料

氢能作为洁净、理想的二次能源,已受到世界各国的广泛关注。然而,氢的储存技术仍然是制约氢能商业化应用的关键技术。利用储氢材料进行储氢被认为是一种安全、高效的固态储氢方式。因此,开发新型高容量的储氢材料与储氢技术成为氢能领域研究的热点之一。纳米限域是将材料填充到纳米孔道里,利用材料和纳米孔道的相互作用促进反应的进行,为化学反应提供一个独特的微环境。近年来,纳米限域逐渐发展成为改善储氢材料热力学和动力学的新方法。本文综述了纳米限域的储氢材料的研究进展,从纳米限域的储氢材料制备、储氢性能、反应机理和存在的问题等方面进行讨论,并指出了纳米限域储氢材料的发展趋势。     

苯电催化加氢反应机理研究

氢能因其清洁、高效、丰富,被认为是新世纪最具潜力、无污染、环保型绿色能源。而氢能的开发和利用是以氢能的存储为前提的。开发安全和廉价的储氢技术成为氢能研究的重点之一。传统的液化储存、金属氢化物储氢和高压压缩储氢技术虽相对较成熟,但尚不适合长距离、大规模氢能输送心。液态有机烃作为储氢介质具有储氢量大（6．18～7．19％）、易于输运（与汽油输运类似）及加氢-脱氢可逆性好的特点（可反复循环,稳定～20年）,是一类具有潜在应用前景的新型储氢材料。     

金属-碳基储氢材料计算与实验研究*

氢能以其资源丰富和环境友好性成为未来最具发展潜力的能源。储氢技术是氢能应用中的关键问题。随着计算材料学的发展,利用密度泛函和量子机制第一性原理研究已知材料储氢性能和寻找潜在的新型优良储氢载体已成为当前研究储氢材料的有效方法。本文综述了近年来金属-碳基储氢材料中的金属修饰碳纳米管、C₆₀材料和过渡金属-乙烯复合物的理论计算与实验研究进展,并对该领域未来的研究工作进行了展望。     

A study of magnetic,antibacterial and antifungal behaviour of a novel gold anchor of polyaniline/itaconic acid/Fe3O4 hybrid nanocomposite: Synthesis and characterization

The objective of the present investigation is to fabricate the gold anchor polyaniline (PANI) based nanocomposites which is prepared using itaconic acid (IA) with Fe₃O₄ by the simple polymerization reaction. The developed multi responsive antibacterial magnetic polymeric composite is represented as Au@PANI–IA–Fe₃O₄. Further, the chemical structure, thermal and magnetic properties such as FT-IR, TGA/DTA, and VSM analysis are studied. The TEM and SEM/EDX are used to find the shape and composition of gold nanoparticles. The enhanced magnetic properties of ferrite composite are exhibited and the antibacterial properties are determined using E. coli (gram -ve) and S. aureus (gram +ve) bacteria’s. The results of biological properties such as antifungal and antimicrobial are also studied critically conferred. Based on the experimental results, the fabrication method of Au@/PANI/IA/Fe₃O₄ magnetic nanocomposites, and the relationship between the structure and biological properties are discussed in detail.     

核壳型纳米粒子合成方法及其性能的研究进展

核壳纳米粒子作为复合纳米粒子一个重要的分支,由于其光、磁和催化等方面的优异性能,近年来引起了人们广泛的关注.本文主要介绍了核壳纳米粒子的制备方法及诸多性能,并对核壳纳米粒子的发展进行了展望.     

系列磺丁基甜菜碱的表征及表面活性

用FT-IR、1H NMR和元素分析对自制的3种磺丁基甜菜碱(SBm-4)的结构进行了表征,研究了它们的表面性能、泡沫性能和乳化性能。 获得SB12-4的cmc为2.20×10-3 mol/L,γcmc为31.48 mN/m;SB14-4的cmc为2.80×10-4 mol/L,γcmc为29.68 mN/m;SB16-4的cmc为2.30×10-5 mol/L,γcmc为32.06 mN/m。 3种磺丁基甜菜碱的cmc值随着烷基链长增加逐渐减小,γcmc先减小后增加,三者的起泡性随浓度增加而增加,到一定值后保持不变;泡沫稳定性随浓度增加逐渐增强,起泡性随着温度的增加有缓慢增加趋势,泡沫稳定性随温度增加逐渐降低。 3种表面活性剂的乳化能力随浓度增加先增加后降低。     

Effect of Cadmium Substitution on Structural and Magnetic Properties of Nano Sized Nickel Ferrite

The structure and crystal phase of the nanocrystalline powders of Ni_1-xCd_xFe₂O₄ (0≤x≤0.5) mixed ferrite, synthesized by wet chemical co-precipitation method, were characterized by X-ray diffraction. Results showed that the lattice parameter increased with increasing Cd concentration. Microstructure was studied by scanning electron microscopy. TG/DTA stud-ies were carried out on co-precipitated sulphate complexes. These studies revealed the low ferritization temperature (650 oC) of the ferrite system synthesized by presently adopted route of synthesis and occurrence of simultaneous decomposition and ferritization processes.Further studies by infrared spectroscopy were also conducted. Moreover, magnetic properties of the prepared nanoparticles were studied by magnetization and a.c. susceptibility mea-surements. The response of prepared Ni_1-xCd_xFe₂O₄ mixed ferrites to magnetic field was investigated. Results show that, magnetic susceptibility, Curie temperature, and effective magnetic moment decreased as the Cd content increases.     

羟基卟啉化合物的电化学、顺磁共振及时间分辨光电压性质

通过循环伏安法、电子顺磁共振谱和时间分辨电压光谱研究了羟基取代基数目和位置的不同对羟基苯基卟啉化合物的电化学、电子顺磁共振和时间分辨光电压性质的影响. 研究结果表明, 所有氧化还原反应都是在卟啉环上进行的. 卟啉周边取代基数目的增加使得卟啉共轭体系平均电子云密度增大, 导致体系易氧化而难以还原. 对称性增强可能使卟啉化合物的半波电位值向正方向移动, 羟基取代基的给电子效应对于卟啉化合物电化学性质的影响起主导作用. 常态下卟啉分子没有EPR信号, 在光的激发下, 卟啉分子由原来的逆磁性分子变成顺磁性的激发三重态分子, 这种激发三重态分子在分子轨道上具有两个未成对电子, 这两个电子相距很近, 彼此之间发生很强的相互作用而产生电子, 它的g值随卟啉共轭体系平均电子云密度增大而变大. 时间分辨光电压是由分子中的自由光声载流子的存在而产生的, 光电压的衰减与分子结构密切相关, 它们的电荷分离速度基本上随卟啉周边羟基取代基数目的增加而减慢.     

Synthesis and characterization of new aromatic poly(ether imide)s and their gas transport properties

A series of processable fluorinated poly(ether imide)s (PIs) were synthesized by reacting a diamine monomer, 1,4-bis-[{2′-trifluromethyl 4′-(4″-aminophenyl)phenoxy}] benzene (HQA) with six different aromatic dianhydrides e.g., BPADA, 6FDA, ODPA, BPDA, BTDA and PMDA. The polyimides showed reasonably high glass-transition temperature (T_g up to 280 °C) and high thermal stability (T_d,10 up to 558 °C). The membranes of these polymers showed tensile strength up to 107 MPa with elongation at break up to 15%, low water absorption (0.61–1.29%), low dielectric constant (2.10–3.13 at 1 MHz) and high optical transparency (λ_cut-off up to 466 nm). The PI membrane prepared from 6FDA exhibited high permeability and permselectivity for O₂/N₂ (P_O2 = 11.8 and P_O2/P_N2 = 9.44) gas pair which eventually surpassed the present upper boundary limit drawn by L.M. Robeson.     

Influence of Backbone Structure on Properties of Directly Polymerized Phenoxy Resins from Epichlorohydrin and Various Aromatic Dihydric Phenols Monomers

A series of phenoxy resins was directly prepared through the polymerization of each of the various aromatic dihydric phenols and epichlorohydrin.FTIR and 1H NMR spectra were recorded to characterize the structures of the re-sins.The GPC curves were used to determine the molecular weight distribution.In addition,the thermal properties of the resins were studied with differential scanning calorimetry(DSC)and thermal gravimetric analysis(TGA).The thermal stabilities of the polymers increased with the content of the benzene ring,pendant group increasing or biphenyl groups emerging.The adhesive properties of the polymers were evaluated in terms of the lap shear strength with Fe-Fe adherends.The fracture mechanisms were determined by SEM observation and it was found that there was an important participation of cohesive fracture mechanisms.Also,it has been demonstrated that the extension of these micro-cohesive mechanisms is directly correlated with the adhesive strength.According to these results,the phenoxy resin containing biphenyl groups presented a higher adhesive strength and could improve the adhesive property of the epoxy/phenoxy system to a certain extent.     

Synthesis, Mesogenic and Spectroscopic Properties of 2,5-Disubstituted Thiophene Derivatives

Two series of 2,5-disubstituted thiophene derivatives （series 1： 2,5-bis（p-alkoxyphenylethynyl）thiophene and series 2： 2,5-bis[p-（p-alkoxyphenylethynyl）（phenylethynyl）]thiophene） were synthesized and characterized by ^1H NMR, ^13C NMR, HRMS and elemental analysis. The relationship between the structure and the mesogenic and spectroscopic properties has been discussed. The results show that compounds 1a-1f all exhibited an enantiotropic nematic mesophase, which was confirmed by the polarized optical microscopy （POM）, differential scanning calorimeter （DSC） and variable temperature powder X-ray diffraction （PXRD）. In contrast, the extended conjugated analogues 2a-2b had no liquid crystal properties. As for the spectroscopic properties, incorporating more phenylethynyl units results in red-shifted absorption and emission spectra, greatly enhanced quantum efficiency.     

分子基磁体Cr[N(CN)2]2电子结构和半金属性的第一性原理研究

The electronic structure and half-metallicity of molecule-based ferromagnet Cr[N(CN)₂]₂ have been investigated using first-principles with generalized gradient approximation. The total energy, spin-polarized electronic band structure, density of states (DOSs) and spin mag-netic moments were all calculated. The calculations reveal that the compound Cr[N(CN)₂]₂ is a really half-metallic ferromagnet with a integral magnetic moment of 2.0000 μB per molecule in the optimized lattice constant. Based on the spin distribution and the DOS, it is found that the total magnetic moment is mainly from the Cr²⁺ with relative small contribution from C and N atoms. The sensitivity of the half-metallicity to small change in lattice constant is also discussed.     

Structural,Electronic and Optical Properties of the Monoclinic α-CoV_2O_6

First-principles calculations based on density functional theory are performed to investigate the structural,electronic and optical properties of monoclinic α-Co V2O6.Firstly,the geometry structures obtained by geometry optimization are consistent with the experimental values.Then,the energy band structure is studied using both GGA and GGA+U methods.It is found that the on-site Coulomb repulsion of the Co 3d orbital plays a key role in describing the electronic properties of α-Co V2O6,and is necessary to open the energy band gap.According to the partial density of states(PDOS),significant Co–O and V–O hybridizations are observed in the valence and conduction bands,respectively.Furthermore,the Co–O and V–O bonds are found to have significant covalent characters.Below the absorption threshold ~1.9 e V,no absorption can be detected.However,there exists a strong and wide absorption band in the energy range from 1.9 to 11 e V.Such novel optical properties imply that the α-Co V2O6 may have some potential optical applications.