A porous metal-organic framework with ultrahigh acetylene uptake capacity under ambient conditions

Acetylene, an important petrochemical raw material, is very difficult to store safely under compression because of its highly explosive nature. Here we present a porous metal-organic framework named FJI-H8, with both suitable pore space and rich open metal sites, for efficient storage of acetylene under ambient conditions. Compared with existing reports, FJI-H8 shows a record-high gravimetric acetylene uptake of 224 cm(3) (STP) g(−1) and the second-highest volumetric uptake of 196 cm(3) (STP) cm(−3) at 295 K and 1 atm. Increasing the storage temperature to 308 K has only a small effect on its acetylene storage capacity (∼200 cm(3) (STP) g(−1)). Furthermore, FJI-H8 exhibits an excellent repeatability with only 3.8% loss of its acetylene storage capacity after five cycles of adsorption–desorption tests. Grand canonical Monte Carlo simulation reveals that not only open metal sites but also the suitable pore space and geometry play key roles in its remarkable acetylene uptake

Enhancing CO2 electrolysis through synergistic control of non-stoichiometry and doping to tune cathode surface structures

K.X. acknowledges Natural Science Foundation of China (91545123) and Natural Science Foundation of Fujian Province (2016J01275) for funding this work. C.L. acknowledges support by the Strategic Priority Research Program of the Chinese Academy of Sciences, Grant No. XDB20000000 and Hundred Talents Program of the Chinese Academy of Sciences. J.T.S.I. acknowledges funding from EPSRC Platform Grant EP/K015540/1 and Royal Society Wolfson Merit Award WRMA 2012/R2.Sustainable future energy scenarios require significant efficiency improvements in both electricity generation and storage. High-temperature solid oxide cells, and in particular carbon dioxide electrolysers, afford chemical storage of available electricity that can both stabilize and extend the utilization of renewables. Here we present a double doping strategy to facilitate CO2 reduction at perovskite titanate cathode surfaces, promoting adsorption/activation by making use of redox active dopants such as Mn linked to oxygen vacancies and dopants such as Ni that afford metal nanoparticle exsolution. Combined experimental characterization and first-principle calculations reveal that the adsorbed and activated CO2 adopts an intermediate chemical state between a carbon dioxide molecule and a carbonate ion. The dual doping strategy provides optimal performance with no degradation being observed after 100 h of high-temperature operation and 10 redox cycles, suggesting a reliable cathode material for CO2 electrolysis.Publisher PDFPeer reviewe

Highly graphitized nitrogen-doped porous carbon nanopolyhedra derived from ZIF-8 nanocrystals as efficient electrocatalysts for oxygen reduction reactions

Nitrogen-doped graphitic porous carbons (NGPCs) have been synthesized by using a zeolite-type nanoscale metal–organic framework (NMOF) as a self-sacrificing template, which simultaneously acts as both the carbon and nitrogen sources in a facile carbonization process. The NGPCs not only retain the nanopolyhedral morphology of the parent NMOF, but also possess rich nitrogen, high surface area and hierarchical porosity with well-conducting networks. The promising potential of NGPCs as metal-free electrocatalysts for oxygen reduction reactions (ORR) in fuel cells is demonstrated. Compared with commercial Pt/C, the optimized NGPC-1000-10 (carbonized at 1000 °C for 10 h) catalyst exhibits comparable electrocatalytic activity via an efficient four-electron-dominant ORR process coupled with superior methanol tolerance as well as cycling stability in alkaline media. Furthermore, the controlled experiments reveal that the optimum activity of NGPC-1000-10 can be attributed to the synergetic contributions of the abundant active sites with high graphitic-N portion, high surface area and porosity, and the high degree of graphitization. Our findings suggest that solely MOF-derived heteroatom-doped carbon materials can be a promising alternative for Pt-based catalysts in fuel cells

Two polymeric 36-metal pure lanthanide nanosize clusters

973 Program [2011CBA00507, 2011CB932504]; National Natural Science Foundation of China [21131006]; Natural Science Foundation of Fujian ProvinceTwo rarely seen 2D coordination polymers based on huge 36-metal pure lanthanide clusters, {[Gd-36(NA)(36)(OH)(49)(O)(6)(NO3)(6)(N-3)(3)(H2O)(20)]Cl-2 center dot 28H(2)O}(n) (1) and {[Dy-36(NA)(36)(OH)(49)(O)(6)(NO3)(6)(N-3)(3-)(H2O)(20)]Cl-2 center dot 28H(2)O}(n) (2) (HNA = nicotinic acid), were synthesized and structurally characterized. The spherical Ln(36) skeleton can be viewed as the aggregation of one cyclohexane chair-like Ln(24) wheel and two identical tripod-like Ln(6) units. The coordination of the carboxylic groups of the NA ligands with the Ln(III) cations results in a square layer. Additionally, compound 1 possesses a large MCE of 39.66 J kg(-1) K-1 and compound 2 exhibits slow relaxation of the magnetization

Anodic formation of nanoporous and nanotubular metal oxides

A localized dielectric breakdown model with good universality is introduced to explain the pore initiation, separation and growth processes of nanoporous and nanotubular anodic metal oxides. It is suggested that the degree of localized dielectric breakdown, which is mainly determined by the dielectric strength and energy band gap of the anodic oxide, electrolyte used, anodizing field and also temperature during anodization, has a significant effect on the pore formation. Continuous nanoporous films tend to grow under low degree of localized dielectric breakdown of the anodic oxides, and the growth in number and size of voids induced by high degree of localized dielectric breakdown at the inter-pore areas leads to the separation of neighbouring pores and, therefore, formation of nanotubular structures. Specially, anodic TiO2 nanotubes are believed to grow by continuous localized dielectric breakdown and self-healing processes at the base of main pores. Alternating dielectric breakdown and oxidation processes at the inter-pores areas lead to the formation of commonly observed O-ring like ridges.</p