Can new hybrid perovskites be predicted using the tolerance factor?

We report a new, simple and versatile method to obtain highly active MOF structures by carefully controlled postsynthesis thermal annealing. The active ZIF-8 structure shows highly enhanced CO 2 /N 2 selectivity and stable cyclic CO 2 uptake of ≥1.5 mmol g -1 at 1 bar and 25 °C with a heat of adsorption of ≥30 kJ mol -1 , which is over 100% greater than the ≈0.7 mmol g -1 and ≈17 kJ mol -1 , respectively in the ZIF-8.Adsorption and separation of gaseous molecules by porous solids is a critical issue in catalysis, sensing, energy storage, CO 2 capture and pollutant removal. 1 In particular, nanoporous solids such as zeolites, carbons and metal-organic frameworks (MOFs) are extensively investigated for clean energy (H 2 and CH 4 ) storage, and separation and capture of pollutant gases (CO 2 , H 2 S, NO x , SO x , I 2 , etc.). 1,2 ZIFs (zeolitic imidazolate frameworks) are a sub-family of MOFs with zeolite-like framework topology, formed from transition metals and imidazolate linkers, and well-known for their remarkable physical, chemical and thermal stability. 3,4 Among those, a prototypical ZIF-8 (Zn[MeIM] 2 = ZnC 8 H 10 N 4 ; MeIM = methylimidazolate) is one of the most studied. Its high BET specific surface area (SSA) (≈ 2000 m 2 g -1 ) and permanent porosity from its uniformly sized pore cavities (of ≈ 1.16 nm and pore volume of ≈ 0.60 cm 3 g -1 ) are particularly desirable for many potential applications, such as molecular gas storage, 3,5 separation by membrane sieving 6 or kinetic diffusion, 7 caging, 8 templating, 9 catalysis, 8-10 and shape-selective distillation 11 and sensing. 12 A large quantity of ZIF-8 can be readily synthesized by simple mixing of precursors of zinc nitrate/acetate and 2methylimidazole in a water or methanol solvent at room temperature. 13 It is also commercially available from Sigma-Aldrich.

We demonstrated the dehydrogenation behaviour of nanoconfined ammonia borane (AB) in Fe-MIL-53, a flexible metal-organic framework (MOF) by solid state thermolysis. We observed clean hydrogen release with fast kinetics at reduced temperatures. 65 85 methanol and stirred for 6 hours at room temperature. The methanol was then dried under vacuum at room temperature for 24 hours to remove the excess methanol. The targeted AB:M ratio was reconfirmed by weighing the initial MIL and AB-MIL after complete vacuum drying process. Samples with 0.5:1, 1:1, 90 and 1.5:1 molar ratios of AB:Fe were prepared. Samples without AB were also prepared in the same way and labelled as 'control'

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As the worldwide demand for energy increases, low-cost solar cells are being looked to as a solution for the future.

Utilising the hugely abundant waste from spent coffee grounds (CGs), KOH activated highly microporous carbons with surface areas of 2785 m 2 g À1 and micropore volumes of 0.793 cm 3 g À1 were synthesised that are capable of uptake capacities near 3 mmol g À1 at 50 C and 1 bar. Importantly such uptake capacities are achieved though the material's superior microporous character and without doping within the carbon matrix, thereby ensuring facile regeneration with a binding enthalpy of only 26 kJ mol À1 and therefore being capable of energy unintensive cycleable adsorption processes. Furthermore, excellent tunability of pore-size is demonstrated from narrow micropores through to narrow mesopores, enabling optimised adsorption over a range of pressures.

Graphitic carbon nitrides (GCNs) represent a family of 2D materials composed of carbon and nitrogen with variable amounts of hydrogen, used in a wide variety of applications. We report a method of room temperature thin film deposition which allows ordered GCN layers to be deposited on a very wide variety of substrates, including conductive glass, flexible plastics, nanoparticles and nano-structured surfaces, where they form a highly conformal coating on the nanoscale. Film thicknesses of below 20 nm are achievable. In this way we construct functional nanoscale heterojunctions between TiO nanoparticles and GCN, capable of producing H photocatalytically under visible light irradiation. The films are hydrogen rich, have a band gap around 1.7 eV, display transmission electron microscopy lattice fringes as well as X-ray diffraction peaks despite being deposited at room temperature, and show characteristic Raman and IR bands. We use cluster etching to reveal the chemical environments of C and N in GCN using X-ray photoelectron spectroscopy. We elucidate the mechanism of this deposition, which operates via sequential surface adsorption and reaction analogous to atomic layer deposition. The mechanism may have implications for current models of carbon nitride formation.

Novel lead and bismuth dipyrido complexes have been synthesized and characterized by single-crystal X-ray diffraction, which shows their structures to be directed by highly oriented π-stacking of planar fully conjugated organic ligands. Optical band gaps are influenced by the identity of both the organic and inorganic component. Density functional theory calculations show optical excitation leads to exciton separation between inorganic and organic components. Using UV-vis, photoluminescence, and X-ray photoemission spectroscopies, we have determined the materials' frontier energy levels and show their suitability for photovoltaic device fabrication by use of electron- and hole-transport materials such as TiO2 and spiro-OMeTAD respectively. Such organic/inorganic hybrid materials promise greater electronic tunability than the inflexible methylammonium lead iodide structure through variation of both the metal and organic components.