Rapid room-temperature synthesis of a porphyrinic MOF for encapsulating metal nanoparticles

While metal nanoparticles(NPs)have shown great promising applications as heterogeneous catalysts,their agglomeration caused by thermodynamic instability is detrimental to the catalytic performance.To tackle this hurdle,we successfully prepared a functional and stable porphyrinic metal-organic framework(MOF),PCN-224-RT,as a host for encapsulating metal nanoparticles by direct stirring at room temperature.As a result,Pt@PCN-224-RT composites with well-dispersed Pt NPs can be constructed by introducing pre-synthesized Pt NPs into the precursor solution of PCN-224-RT.Of note,the rapid and simple stirring method in this work is more in line with the requirements of environmental friendly and industrialization compared with traditional solvothermal methods.

GaN晶体的生长及其低维材料的制备

Wurtzite strcture gallium nitride, GaN,a direct bandgap semiconductor (3.4 eV at room temperature),is an ideal material for fabrication of blue/green light emit ti ng diodes, laser diodes,and high power integrated circuits.Recent progress in th in film crystal technique has realized the output of blue semiconductor lasers w i th a lifetime of over 10000 hours under continuous wave operation at room tempe r ature.So far GaN and its ternary indium and aluminum alloys are grown almost uni v ersally on foreign substrates with varying lattice mismatches.The mismatch undou btedly results in a significant dislocation density in the grown films.Hence it is necessary to grow single crystal GaN to be used as substrates for improvement of laser diodes.On the other hand,low dimensional GaN materials such as nanocry stalline powder,nanocrystal assembled bulk(nanophase) and nano wires are very u seful in both fundamental mesoscopic research and future development of GaN nano devices.Here we report our main recent progresses on the crystal growth of GaN a nd the preparation of its low dimensional materials.

Effect of Argon Addition on Morphology and Structure of Diamond Films(from Microcrystalline to Nanocrystalline)

Micro-/nanocrystalline diamond films deposited in Ar/H2/CH4 microwave plasmas have been studied, with argon flow rates in the range of 70-100 sccm. The effects of argon addition on morphology, surface roughness, quality and structure were investigated by scanning electron microscopy, surface profiler, Raman spectrometer and X-ray diffraction （XRD）. It is demonstrated that when the argon flow rate is 70 sccm or 75 sccm, well-faceted polycrystalline diamond films can be grown at a low substrate temperature less than 610 ~C. With the increase in the argon flow rate, the smooth crystallographic planes disappear gradually. Instead, rough crystallographic planes made up of small aggregates begin to take shape, resulting from the increase in the secondary nucleation rate. Nanocrystalline diamond films were obtained at a flow rate of 100 sccm, and all of the prepared diamond films were smooth, with a surface roughness （Ra） less than 20 nm. Raman analyses reveal that the amount of amorphous carbon increases significantly with the increase in argon flow. The results of XRD show that crystalline size and preferential orientation of diamond films depend on the argon content in the plasmas.

Efficient hexane isomers separation in isoreticular bipyrazolate metal-organic frameworks:The role of pore functionalization

Hydrocarbons separation in petrochemical industries is a key,energy-consuming stage in the manufacture of high-quality added-value products—hence the need for more efficient materials and environmentally friendly methodologies to improve this process.In this context,we have studied the effect of metal-organic frameworks(MOFs)pore functionalization in hexane isomers separation,isolating the robust isoreticular zinc(ll)bipyrazolates Zn(BPZ),showing no pore decoration,Zn(Me_(2)BPZ),the pores of which are decorated with apolar methyl groups,and Zn(BPZ(NH_(2))_(2)),the spacers of which possess polar Lewis-basic functions(H_(2)BPZ=1H,1'H-4,4'-bipyrazole;H_(2)Me_(2)BPZ=3,3'-dimethyl-1H,1'H-4,4'-bipyrazole;H_(2)BPZ(NH_(2))_(2)=3,5-diamino-1H,1'H-4,4'-bipyrazole;DMF=dimethylformamide).After characterizing Zn(BPZ(NH_(2))_(2))as per its crystal structure and thermal behaviour,and all the three MOFs as per their textural properties,we investigated,from the experimental and computational points of view,the impact of the square one-dimensional channels decoration on the separation of the hexane isomers,demonstrating the relevance of pore constrictions in the resolution of the title alkanes mixture.