Synthesis and conductivity of substituted heteropoly acid with Dawson structure H_7[Ga(H_2O)P_2W_(17)O_(61)].18H_2O

A new solid high-proton conductor,H7[Ga(H2O)P2W17O61].18H2O,a substituted heteropoly acid with Dawson structure,has been synthesized by the degradation/ion-exchange/freezing method.The product was characterized by potentiometric titration,chemical analysis,IR,UV,XRD and TG-DTA.Complex impedance measurements show a high conductivity(5.44×10-3 S/cm at 50℃),with an activation energy for proton conduction of 36.04 kJ/mol.The mechanism of proton conduction is the Vehicle mechanism.

Oxygen vacancy engineering of calcium cobaltate:A nitrogen fixation electrocatalyst at ambient condition in neutral electrolyte

In order to sustainably transform N2 to ammonia(NRR)using electrocatalysts under mild ambient condition,it is urgent to design and develop non-nobel metal nanocatalysts that are inexpensive and suitable for mass-production.Herein,a calcium metalate catalyst CaCoO_(x)with oxygen vacancies was synthesized and used as an electrocatalyst for NRR for the first time,whose morphology can be controlled by the calcination temperature and the heating rate.Under the optimal conditions,the CaCoO_(x)catalyst achieved the yield of nitrogen conversion to ammonia of 16.25μg·h^(-1)·mg_(cat.)^(-1)at the potential of-0.3 V relative to the reversible hydrogen electrode(RHE)with a Faraday efficiency of 20.51%.The electrocatalyst showed good stability even after 12 times recyclability under environmental conditions and neutral electrolyte.Later,the electrocatalytic nitrogen reduction performance of CaFeO_(x),CaNiO_(x),CaCuO_(x)was investigated.These earth-rich transition metals also exhibited certain NRR electrocatalytic capabilities,which provided a door for further development of inexpensive and easily available transition metal as nitrogen reduction electrocatalysts.

Conformational and Dynamical Evolution of Block Copolymers in Shear Flow

Conformation and dynamical evolution of block copolymers in shear flow is an important topic in polymer physics that underscores the forming process of various materials.We explored deformation and dynamics of copolymers composed of rigid or flexible blocks in simple shear flow by employing multiparticle collision dynamics integrated with molecular dynamics simulations.We found that compared with the proportion between rigid and flexible blocks,the type of the central blocks plays more important role in the conformational and dynamical evolution of copolymers.That is,if the central block is a coil,the copolymer chain takes end-over-end tumbling motion,while if the central block is a rod,the copolymer chain undergoes U-shape or S-shape deformation at mid shear rate.As the shear strength increases,all copolymers behave similar to flexible polymers at high shear rate.This can be attributed to the fact that shear flow is strong enough to overcome the buckling force of the rigid blocks.These results provide a deeper understanding of the roles played by rod and coil blocks in copolymers for phase interface during forming processing.

A bipolar metal phthalocyanine complex for sodium dual-ion battery

Dual-ion batteries(DIBs) have attracted immense interest as a new generation of energy storage device due to their low cost,environmental friendliness and high working voltage.However,developing DIBs using organic compounds as active electrode materials is in its infancy.Herein,we first report a bipolar and self-polymerized Cu phthalocyanine(CuTAPc) as an electrode material for sodium-based DIBs(SDIBs).Benefitting from the bipolar property,CuTAPc could serve as the cathode or anode material to construct metal sodium-based or metal sodium-free SDIB(cell 1 or 2) by coupling with sodium anode or graphite cathode,respectively.As a result,cell 1 displays a high discharge capacity of 195.7 mAh g^(-1) at 50 mA g^(-1) and a high reversible capacity of 57 mAh g^(-1) over 2500 cycles at 1 A g^(-1),and cell 2 shows a high energy density of 324 Wh kg^(-1) and a high power density of 7481 W kg^(-1).Subsequently,the proposed binding mechanism and the bipolar reactivity of CuTAPc have been revealed by the detailed reaction kinetic analysis and ex-situ techniques as well as the density functional theory(DFT) calculations.This work could open a pathway to develop the advanced SDIBs constructed by elemental abundant and environmentally friendly organic materials.

A strategy for highly dispersed Mo2C/MoN hybrid nitrogen- doped graphene via ion-exchange resin synthesis for efficient electrocatalytic hydrogen reduction

Molybdenum carbide/molybdenum nitride hybrid N-doped graphene （abbreviated as Mo2C/MoN/NG）, as an efficient electrocatalyst for the hydrogen evolution reaction （HER）, was synthesized via simple ion-exchange resin synthesis followed by a two-step annealing process, which increased the dispersion degree of the electrocatalyst＇s active sites on the support skeleton and simplified the synthetic conditions. Additionally, N-doped graphene （NG） enhanced the electron transfer and reduced the inner resistance. The material has a graphene-like morphology and highly dispersed Mo2C/MoN nanoparticles about 2 nm in diameter on the NG. X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy revealed that Mo2C/MoN/NG consisted of Mo2C and MoN composited together. Finally, Mo2C/MoN/NG exhibited remarkable performance as an electrocatalyst for the HER with a small overpotential of 78.82 mV and a small Tafel slope of 39.3 mV.dec^-1 in a 0.5 mol.L-1 H2SO4 solution. Its activity was approximately 30% lower than that of 20% Pt/C and 60% higher than that of NG. Also, it exhibited a low onset overpotential of 24.82 mV, which is similar to the theoretical HER potential. Our work provides a foundation for advanced HER applications of molybdenum compounds.

以多孔芳香骨架材料PAF-1作为对映选择性有机催化的超稳定固载平台（英文）

PAF-1是最著名的多孔芳香骨架材料(PAF),它拥有许多优异的性质并且可被用于多个领域.由高密度的苯环组成的PAF-1材料拥有刚性结构和亲脂性孔道,非常适合用作有机催化的平台.但是迄今为止,尚未有将其应用到对映选择性有机催化的报道.本论文以PAF-1为固载平台,将手性脯氨酰胺催化位点通过一系列后修饰的方法固载到PAF-1的骨架上,得到了新颖的手性固载催化剂PAF-1-NHPro.PAF-1-NHPro在催化对硝基苯甲醛和环己酮的Aldol反应的过程中表现出了优良的非对映选择性和对映选择性以及良好的可回收利用性.本工作展现了PAF材料在非均相对映选择性有机催化领域的应用前景.