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We present results of investigations into improving methods by which gas sorption data are collected and reported. The focus is the accurate comparison of hydrogen storage capacities of different nanoporous materials. The aim is to produce a more rigorous approach to the assessment of the hydrogen storage capacities of different nanoporous materials through formulation of meticulous and systematic data collection routines for production of universally reproducible H2 isotherms over a wide range of pressure and temperature conditions. Effects of a range of experimental variables are examined and recommendations for the optimisation of data collection routines are given.

The changing face of cisplatin: The complete crystal structures, including the details of extensive intermolecular hydrogen bonding in two enantiotropic polymorphs of the chemotherapeutic drug cisplatin, have been elucidated. A massive thermal hysteresis effect exists between the two polymorphs, α and β, that are active at ambient temperatures.

A polyhydroxybutyrate (PHB) producing cyanobacteria was converted through hydrothermal liquefaction (HTL) into propylene and a bio-oil suitable for advanced biofuel production. HTL of model compounds demonstrated that in contrast to proteins and carbohydrates, no synergistic effects were detected when converting PHB in the presence of algae. Subsequently, Synechocystis cf. salina, which had accumulated 7.5 wt% PHB was converted via HTL (15% dry weight loading, 340 °C). The reaction gave an overall propylene yield of 2.6%, higher than that obtained from the model compounds, in addition to a bio-oil with a low nitrogen content of 4.6%. No propylene was recovered from the alternative non-PHB producing cyanobacterial strains screened, suggesting that PHB is the source of propylene. PHB producing microorganisms could therefore be used as a feedstock for a biorefinery to produce polypropylene and advanced biofuels, with the level of propylene being proportional to the accumulated amount of PHB.

Experimental hydrogen isotherms on several metal-organic frameworks (IRMOF-1, IRMOF-3, IRMOF-9, ZIF-7, ZIF-8, ZIF-9, ZIF-11, ZIF-12, ZIF-CoNIm, MIL-101 (Cr), NH2-MIL-101 (Cr), NH2-MIL-101 (Al), UiO-66, UiO-67 and HKUST-1) synthesized in-house and measured at 77 K and pressures up to 18 MPa are presented, along with N2 adsorption characterization. The experimental isotherms together with literature high pressure hydrogen data were analysed in order to search for relationships between structural properties of the materials and their hydrogen uptakes. The total hydrogen capacity of the materials was calculated from the excess adsorption assuming a constant density for the adsorbed hydrogen. The surface area, pore volumes and pore sizes of the materials were related to their maximum hydrogen excess and total hydrogen capacities. Results also show that ZIF-7 and ZIF-9 (SOD topology) have unusual hydrogen isotherm shapes at relatively low pressures, which is indicative of “breathing”, a phase transition in which the pore space increases due to adsorption. This work presents novel and more useful correlations using the modelled total hydrogen capacities of several MOFs. These total hydrogen capacities are more practically relevant for energy storage applications than the measured excess hydrogen capacities. Thus, these structural correlations will be advantageous for the prediction of the properties a MOF will need in order to meet the US Department of Energy targets for the mass and volume of on-board storage systems. Such design tools will allow hydrogen to be used as an energy vector for sustainable mobile applications such as transport, or for providing supplementary power to the grid in times of high demand.

A range of low-cost nanoparticulate mixed transition metal oxides were prepared using a simple methodology and used as catalysts in visible light promoted water oxidations. The effect of catalyst and daylight equivalent light intensities on reaction efficiency in terms of O2 yields, TOF and proton production was determined.

Electron diffraction is used to investigate the large amplitude displacive disorder characteristic of the Bi 2 ( M III Nb V )O 7 Bi-pyrochlores, Bi 2 InNbO 7 and Bi 2 FeNbO 7 , as well as of their A site substituted Bi 1.5 Y 0.5 InNbO 7 and Bi 1.5 Y 0.5 FeNbO 7 variants. Highly structured diffuse distributions in the form of {110}* sheets of diffuse intensity perpendicular to the six 〈110〉 directions of real space along with 〈111〉* rods of diffuse intensity perpendicular to the four {111} real space planes are observed. The existence of this structured diffuse scattering is interpreted in terms of large amplitude, β -cristobalite-type tetrahedral rotations of the O′ A 2 tetrahedral framework sub-structure of the ideal pyrochlore structure type. Bond valence sum calculations are used to understand the local crystal chemistry responsible for such displacive disorder. The frequency-dependent dielectric properties of Bi 2 InNbO 7 and Bi 2 FeNbO 7 are also investigated along with the effect upon them of A site doping with Y.

The binary pnictide ‘SnSb’ has been re-investigated using a combination of X-ray, synchrotron and electron diffraction as well as electron microprobe analysis. Its structure was found to be incommensurately modulated with an underlying rhombohedral parent structure of space group symmetry R 3 ¯ m (No. 166), unit cell parameters a h = b h = 4.3251 ( 4 ) A , c h = 5.3376 ( 6 ) A in the hexagonal setting. The incommensurate primary modulation wave vector q h = 1 . 3109 ( 9 ) c h * and the superspace group symmetry is R 3 ¯ m (0, 0, ∼1.311) (No. 166.1). The refinement of the incommensurate structure indicates that the satellite reflections arise from displacive shifts of presumably essentially pure Sn and Sb layers along the hexagonal c-axis, with increasing distance between the Sn-layers and decreasing distance between the Sb layers.

The structures of the Ba{sub 2}InNbO{sub 6}, Sr{sub 2}InNbO{sub 6} and Ca{sub 2}InNbO{sub 6} ''1:1'' complex perovskites have been refined from neutron powder diffraction data. Both the A=Ca and Sr compounds occur at room temperature in P12{sub 1}/n1 (a=a{sub p}+b{sub p}, b=-a{sub p}+b{sub p}, c=2c{sub p}) perovskite-related superstructures while the A=Ba compound occurs in the Fm3-bar m, a=2a{sub p}, elpasolite structure type. In the case of the A=Ca compound, an extensive Ca{sub 2}[(Ca{sub 2x/3}In{sub 1-x}Nb{sub x/3})Nb]O{sub 6} 'solid solution' field spanning compositions between Ca{sub 4}Nb{sub 2}O{sub 9} and Ca{sub 2}InNbO{sub 6} in the CaO-InO{sub 3/2}-NbO{sub 5/2} ternary phase diagram is shown to exist. Under the conditions of synthesis used, the 'solid solution' field stops just short of the ideal 1:1 Ca{sub 2}InNbO{sub 6} composition.

A combined synthesis, diffraction and dielectric properties investigation of the dependence (and effect) of Mn2+/Nb5+ ordering in Ba3MnNb2O9 (BMN) upon annealing atmosphere and processing conditions has been carried out. Annealing in different atmospheres was not found to significantly alter either nominal stoichiometry or structure type. The obtained structure type (disordered metrically cubic or ordered trigonal) as well as the measured electrical properties (in particular, the dielectric loss) were, however, found to be sensitive to the synthesis route. Samples obtained via solid-state reaction were found to be predominantly of 1:2 Mn2+/Nb5+ ordered, P 3 ¯ m 1 trigonal structure type whereas samples obtained via an aqueous solution route were found to be of a Mn2+/Nb5+ ‘disordered’, metrically cubic structure type. All solid-state synthesized samples showed reasonable dielectric properties. The microwave dielectric constant and dielectric quality factor, Q, at 8 GHz of an as-synthesized BMN sample were 38 and 100, respectively. By contrast, the dielectric loss of the metrically cubic, Mn2+/Nb5+ ‘disordered’ samples obtained via an aqueous solution synthesis process were significantly worse.

The structure of the pyrochlore-type oxide Bi2InNbO7 has been investigated between room temperature and 700 °C using electron and synchrotron X-ray powder diffraction and at room temperature and 10 K using neutron diffraction methods. Bi2InNbO7 exhibits an A2B2O7 cubic pyrochlore-type average structure at all temperatures that is characterized by an apparently random mixing of the In3+ and Nb5+ cations on the octahedral B sites. The Bi cations on the eight-coordinate pyrochlore A sites are displacively disordered, presumably as a consequence of their lone pair electron configuration. Heating the sample does not alter this disorder.

The room temperature structures as well as the temperature-dependent conductivity and dielectric properties of the A3CoNb2O9 (A=Ca2+, Sr2+ and Ba2+) triple perovskites have been carefully investigated. A constrained modulation wave approach to Rietveld structure refinement is used to determine their room temperature crystal structures. Correlations between these crystal structures and their physical properties are found. All three compounds undergo insulator to semiconductor phase transitions as a function of increasing temperature. The hexagonal Ba3CoNb2O9 compound acts as an insulator at room temperature, while the monoclinic Ca3CoNb2O9 compound is already a semiconductor at room temperature. The measured dielectric frequency characteristics of the A=Ba compound are excellent.

A careful investigation has been carried out into the space group symmetries, structures and crystal chemistries of the 1:2 B-site ordered triple perovskites A3Co2+Nb5+2O9 (A=Ca2+, Sr2+, Ba2+) using a combination of bond valence sum calculations, powder XRD and electron diffraction. A recent investigation of these compounds by Yin et al. reported a random distribution of Co2+ and Nb5+ ions onto the perovskite B-site positions and hence Pm 3 m (a=ap, subscript p for parent perovskite sub-structure) space group symmetry for the A=Ba and Sr compounds and a monoclinically distorted variant thereof (although no space group was given) in the case of the A=Ca compound. An electron diffraction study, however, shows that the A=Ba compound occurs in a 1:2 B site ordered trigonal P 3 m1 , a h = b p − c p , b h = c p − a p , c h = a p + b p + c p structure type while both the A=Ca and Sr compounds occur at room temperature in monoclinic P121/c1, a m =[ 1 1 2] p , b m =[1 1 0] p , c m =3[110] p , perovskite-related structure types. The latter monclinic structure type can be described as a modulated variant of the 1:2 B site ordered trigonal P 3 m1 structure type with the additional modulations associated with a b–b−c+ octahedral tilt sequence. Bond valence sum calculations are used to explain why this should be so as well as to provide a useful zeroth-order approximation to the structures of each of the compounds.

Improvements in the efficiency of combustion within a vehicle can lead to reductions in the emission of harmful pollutants and increased fuel efficiency. Gas sensors have a role to play in this process, since they can provide real time feedback to vehicular fuel and emissions management systems as well as reducing the discrepancy between emissions observed in factory tests and ‘real world’ scenarios. In this review we survey the current state-of-the-art in using porous materials for sensing the gases relevant to automotive emissions. Two broad classes of porous material – zeolites and metal–organic frameworks (MOFs) – are introduced, and their potential for gas sensing is discussed. The adsorptive, spectroscopic and electronic techniques for sensing gases using porous materials are summarised. Examples of the use of zeolites and MOFs in the sensing of water vapour, oxygen, NOx, carbon monoxide and carbon dioxide, hydrocarbons and volatile organic compounds, ammonia, hydrogen sulfide, sulfur dioxide and hydrogen are then detailed. Both types of porous material (zeolites and MOFs) reveal great promise for the fabrication of sensors for exhaust gases and vapours due to high selectivity and sensitivity. The size and shape selectivity of the zeolite and MOF materials are controlled by variation of pore dimensions, chemical composition (hydrophilicity/hydrophobicity), crystal size and orientation, thus enabling detection and differentiation between different gases and vapours.

The potential of neutron powder diffraction in the location of hydrogen atoms in molecular materials and inorganic-molecular complexes is reviewed. Advances in instrumentation and data collection techniques that have made this field accessible are reviewed, along with a wide range of applications carried out by our collaboration investigating functional materials, hydrogen-containing minerals and molecular compounds. Some of the limitations in this area, particularly for molecular systems, are also addressed.

Upon heating, the 1:2 triple perovskites A3CoNb2O9 (A=Ca, Sr or Ba) each undergo well-defined insulator to conductor phase transitions at ∼8, ∼126 and ∼325 °C, respectively. As the trend in the transition temperatures for these materials does not correlate with the size of the reported band gaps, neutron powder diffraction has been used to investigate if this change in electrical behaviour of the materials was due to a structural phase change. It was found that in the regions of the suspected phase transitions there were only slight perturbations of the structures, namely thermal expansion of the lattices and an apparent muting of the amplitude of the octahedral rotations in the A=Ca and Sr compound at higher temperatures.

This paper considers stacking fault disorder in Ba3M1Nb2O9 (M=Mn2+ or Co2+) 1:2 triple perovskites and how best to model it when refining neutron powder diffraction data. The true local structures of both samples were successfully refined using a coherent stacking fault disordered model. The stacking fault disorder in Ba3MnNb2O9 and Ba3CoNb2O9 affects their dielectric properties.

A sound understanding of any sorption system requires an accurate determination of the enthalpy of adsorption. This is a fundamental thermodynamic quantity that can be determined from experimental sorption data and its correct calculation is extremely important for heat management in adsorptive gas storage applications. It is especially relevant for hydrogen storage, where porous adsorptive storage is regarded as a competing alternative to more mature storage methods such as liquid hydrogen and compressed gas. Among the most common methods to calculate isosteric enthalpies in the literature are the virial equation and the Clausius–Clapeyron equation. Both methods have drawbacks, for example, the arbitrary number of terms in the virial equation and the assumption of ideal gas behaviour in the Clausius–Clapeyron equation. Although some researchers have calculated isosteric enthalpies of adsorption using excess amounts adsorbed, it is arguably more relevant to applications and may also be more thermodynamically consistent to use absolute amounts adsorbed, since the Gibbs excess is a partition, not a thermodynamic phase. In this paper the isosteric enthalpies of adsorption are calculated using the virial, Clausius–Clapeyron and Clapeyron equations from hydrogen sorption data for two materials—activated carbon AX-21 and metal-organic framework MIL-101.It is shown for these two example materials that the Clausius–Clapeyron equation can only be used at low coverage, since hydrogen’s behaviour deviates from ideal at high pressures. The use of the virial equation for isosteric enthalpies is shown to require care, since it is highly dependent on selecting an appropriate number of parameters. A systematic study on the use of different parameters for the virial was performed and it was shown that, for the AX-21 case, the Clausius–Clapeyron seems to give better approximations to the exact isosteric enthalpies calculated using the Clapeyron equation than the virial equation with 10 variable parameters.

The potential of neutron powder diffraction (NPD) to provide vital information on the determination of accurate hydrogen positions in organic molecular crystals is demonstrated through the study of a series of hydrogen bonded molecular complexes with relevance in crystal engineering. By studying complexes designed to contain short, strong hydrogen bonds, the findings are shown to be of particular importance in the study of proton transfer, and the often critical distinction between neutral complexes and salts in these molecular materials. The use of combined NPD and single crystal X-ray diffraction is shown to be particularly potent in this area.

Experimental excess isotherms for the adsorption of gases in porous solids may be represented by mathematical models that incorporate the total amount of gas within a pore, a quantity which cannot easily be found experimentally but which is important for calculations for many applications, including adsorptive storage. A model that is currently used for hydrogen adsorption in porous solids has been improved to include a more realistic density profile of the gas within the pore, and allows calculation of the total amount of adsorbent. A comparison has been made between different Type I isotherm equations embedded in the model, by examining the quality of the fits to hydrogen isotherms for six different nanoporous materials. A new Type I isotherm equation which has not previously been reported in the literature, the Unilanb equation, has been derived and has also been included in this comparison study. These results indicate that whilesome Type I isotherm equations fit certain types of materials better than others, the Toth equation produces the best overall quality of fit and also provides realistic parameter values when used to analyse hydrogen sorption data for a model carbon adsorbent.

Aligned carbon nanotube (CNT) arrays over 150 μm long have been grown by catalytic chemical vapour deposition on the walls of bare cordierite monoliths in a single step. The method described avoids the need for the multiple pre-treatment steps currently applied, and is coupled with an increase in the thickness of the carbon layer obtained by an order of magnitude compared to literature. Uniform CNT growth has been obtained over different lengths of monolith. The resulting CNT/cordierite monoliths have a high surface area and low pressure drop, making them a viable support for use in industrial catalysis.

We demonstrate the extent to which modern detector technology, coupled with a high flux constant wavelength neutron source, can be used to obtain high quality diffraction data from short data collections, allowing the refinement of the full structures (including hydrogen positions) of hydrous compounds from in situ neutron powder diffraction measurements. The in situ thermodiffractometry and controlled humidity studies reported here reveal that important information on the reorientations of structural water molecules with changing conditions can be easily extracted, providing insight into the effects of hydrogen bonding on bulk physical properties. Using crystalline BaCl 2·2H 2O as an example system, we analyse the structural changes in the compound and its dehydration intermediates with changing temperature and humidity levels to demonstrate the quality of the dynamic structural information on the hydrogen atoms and associated hydrogen bonding that can be obtained without resorting to sample deuteration.

A robust, simple methodology for analysis of isotherms for the adsorption of fluids above their critical temperature onto nanostructured materials is presented. The analysis of hydrogen adsorption in a metal-organic framework is used as an example to illustrate the methodology, which allows the estimation of the absolute adsorption into nanoporous systems. Further advantages of employing this analysis are that adsorption systems can be described using a small number of parameters, and that excess and absolute isotherms can be extrapolated and used to predict adsorption behaviour at higher pressures and over different temperature ranges. Thermodynamic calculations, using the exact Clapeyron equation and the Clausius-Clapeyron approximation applied to the example dataset, are presented and compared. Conventional compression of hydrogen and adsorptive storage are evaluated, with an illustration of the pressure ranges in which adsorption facilitates storage of greater volumes of hydrogen than normal compression in the same operating conditions.

Hydrogen forms more compounds than any other element in the Periodic Table, yet methods for accurately, precisely and rapidly determining its position in a crystal structure are not readily available. The latest generation of high-flux neutron powder diffractometers, operating under optimised collection geometries, allow hydrogen positions to be extracted from the diffraction patterns of polycrystalline hydrogenous compounds without resorting to isotopic substitution. Neutron powder diffraction for hydrogenous materials has a wide range of applications within chemistry. These include the study of hydrogen-energy materials, coordination and organometallic compounds, hydrogen-bonded structures and ferroelectrics, geomaterials, zeolites and small molecule organics, such as simple sugars and amino acids. The technique is particularly well suited to parametric studies, for example as a function of temperature or pressure, where changes in hydrogen bonding patterns or decompositions involving hydrogen-containing molecules, such as water, are monitored.

Hydrogen forms more compounds than any other element in the Periodic Table, yet methods for accurately, precisely and rapidly determining its position in a crystal structure are not readily available. The latest generation of high-flux neutron powder diffractometers, operating under optimised collection geometries, allow hydrogen positions to be extracted from the diffraction patterns of polycrystalline hydrogenous compounds without resorting to isotopic substitution. Neutron powder diffraction for hydrogenous materials has a wide range of applications within chemistry. These include the study of hydrogen-energy materials, coordination and organometallic compounds, hydrogen-bonded structures and ferroelectrics, geomaterials, zeolites and small molecule organics, such as simple sugars and amino acids. The technique is particularly well suited to parametric studies, for example as a function of temperature or pressure, where changes in hydrogen bonding patterns or decompositions involving hydrogen-containing molecules, such as water, are monitored.

Refers To Nuno Bimbo, Wesley Xu, Jessica E. Sharpe, Valeska P. Ting, Timothy J. Mays High-pressure adsorptive storage of hydrogen in MIL-101 (Cr) and AX-21 for mobile applications: Cryocharging and cryokinetics Materials & Design, Volume 89, 5 January 2016, Pages 1086-1094 The authors regret to inform that….. The Supplementary Information should have been included in the original paper and is now provided with this corrigendum. All the data and figures, contained in the manuscript and supporting information, are available and can be accessed free of charge at http://dx.doi.org/10.15125/BATH-00099. Any questions related to the data should be addressed to the corresponding author. Authors would like to apologize for the inconvenience caused.

The reported wide-range nonstoichiometric Ni1+xTe2, 0≤x≤0.83, and Ni1+xSe2, 0.57≤x≤0.92, CdI2/NiAs structure type solid solution fields have been carefully reinvestigated via electron and X-ray powder diffraction to search for evidence of Ni/vacancy ordering and superstructure phases. In the case of telluride, evidence is thereby found for a Ni3Te4 superstructure phase attempting to condense out at x∼0.5 while, in the case of selenide, three quite distinct phases have been identified within the Ni1+xSe2 solid solution field. An intriguing characteristic honeycomb diffuse-intensity distribution has also been observed across the solid solution field in the case of the Ni1+xTe2 system. Its presence has been attributed to low frequency phonon modes along certain very specific directions of reciprocal space.

The hydrations of the excipients stable α-lactose (Lαs), with two particle sizes, and trehalose have been studied by neutron powder diffraction; analysis of the Avrami plots, derived from the bulk polycrystalline phase compositions, allows elucidation of the kinetics and mechanisms involved in these hydration processes.

Hydrogen is a fundamentally important element in many key areas of inorganic materials design, including development of technological materials (e.g. hydrogen storage media and protonconductor fuel cell components), functional framework materials (e.g. zeolites), inorganic catalysts, organometallic co ordination complexes and inorganic hydrates. Due to the weak scattering of Xrays by light elements, and hydrogen’s large incoherent neutron background, determination of hydrogen positions in inorganic materials, where possible, traditionally necessitates costly sample deuteration or painstaking synthesis of large single crystals for neutron diffraction. This limitation is now being addressed through the development of experimental and data refinement methodologies which utilise very high flux neutron powder diffractometers, such as D20 at ILL.