Colloidal lead halide perovskite nanocrystals (NCs) have recently emerged as a novel class of bright emitters with pure colors spanning the entire visible spectral range. Contrary to conventional quantum dots, such as CdSe and InP NCs, perovskite NCs feature unusual, defect-tolerant photophysics. Specifically, surface dangling bonds and intrinsic point defects such as vacancies do not form midgap states, known to trap carriers and thereby quench photoluminescence (PL). Accordingly, perovskite NCs need not be electronically surface-passivated (with, for instance, ligands and wider-gap materials) and do not noticeably suffer from photo-oxidation. Novel opportunities for their preparation therefore can be envisaged. Herein, we show that the infiltration of perovskite precursor solutions into the pores of mesoporous silica, followed by drying, leads to the template-assisted formation of perovskite NCs. The most striking outcome of this simple methodology is very bright PL with quantum efficiencies exceeding 50%. This facile strategy can be applied to a large variety of perovskite compounds, hybrid and fully inorganic, with the general formula APbX3, where A is cesium (Cs), methylammonium (MA), or formamidinium (FA), and X is Cl, Br, I or a mixture thereof. The luminescent properties of the resulting templated NCs can be tuned by both quantum size effects as well as composition. Also exhibiting intrinsic haze due to scattering within the composite, such materials may find applications as replacements for conventional phosphors in liquid-crystal television display technologies and in related luminescence down-conversion-based devices.

The 100 th anniversary of Langmuir's theory of adsorption is a significant landmark for the physical chemistry and chemical engineering communities. Despite its simplicity, the Langmuir adsorption model captures the key physics of molecular interactions at interfaces and laid the foundation for further progress in understanding interfacial phenomena, developing new adsorbent materials, and designing engineering processes. The Langmuir model has had an exceptional impact on diverse fields within the chemical sciences ranging from chemical biology to materials science , an impact that became clearer with the development of modified adsorption theories and continues to be relevant today.

Adsorbed methane makes up a large portion of the total shale gas-in-place (GIP) resource in deep shale formations. In order to accurately estimate the shale GIP resource, it is crucial to understand the relationship between the adsorbed methane quantity and the free methane quantity of shale gas in shale formations (under high pressure conditions). This work describes and accurately predicts high pressure methane adsorption behavior in Longmaxi shale (China) using a dual-site Langmuir model. Laboratory measurements of high pressure methane adsorption (303-355 K and up to 27 MPa) are presented. Our findings show that for depths greater than 1000 m (> 15 MPa) in the subsurface, the shale gas resources have historically been significantly overestimated. For Longmaxi shale (2500-3000 m in depth), classical approaches overestimate the GIP by up to 35%. The ratio of the adsorbed phase compared to the free gas has been significantly underestimated. The methods used herein allow accurate estimations of the true shale GIP resource and the relative quantity of adsorbed methane at in situ temperatures and pressures representative of deep shale formations.

High surface area porous carbon frameworks exhibit potential advantages over crystalline graphite as an electrochemical energy storage material owing to the possibility of faster ion transport and up to double the ion capacity, assuming a surface-based mechanism of storage. When detrimental surface-related effects such as irreversible capacity loss due to interphase formation (known as solid-electrolyte interphase, SEI) can be mitigated or altogether avoided, the greatest advantage can be achieved by maximizing the gravimetric and volumetric surface area and by tailoring the porosity to accommodate the relevant ion species. We investigate this concept by employing zeolite-templated carbon (ZTC) as the cathode in an aluminum battery based on a chloroaluminate ionic liquid electrolyte. Its ultrahigh surface area and dense, conductive network of homogeneous channels (12 Å in width) render ZTC suitable for the fast, dense storage of AlCl ions (6 Å in ionic diameter). With aluminum as the anode, full cells were prepared which simultaneously exhibited both high specific energy (up to 64 Wh kg, 30 Wh L) and specific power (up to 290 W kg, 93 W L), highly stable cycling performance, and complete reversibility within the potential range of 0.01-2.20 V.

A thermodynamic study of the enthalpy of adsorption of methane on high surface area carbonaceous materials was carried out from 238 to 526 K. The absolute quantity of adsorbed methane as a function of equilibrium pressure was determined by fitting isotherms to a generalized Langmuir-type equation. Adsorption of methane on zeolite-templated carbon, an extremely high surface area material with a periodic arrangement of narrow micropores, shows an increase in isosteric enthalpy with methane occupancy; i.e., binding energies are greater as adsorption quantity increases. The heat of adsorption rises from 14 to 15 kJ/mol at near-ambient temperature and then falls to lower values at very high loading (above a relative site occupancy of 0.7), indicating that methane/ methane interactions within the adsorption layer become significant. The effect seems to be enhanced by a narrow pore-size distribution centered at 1.2 nm, approximately the width of two monolayers of methane, and reversible methane delivery increases by up to 20% over MSC-30 at temperatures and pressures near ambient.

IntroductionAdditional materials characterization and data analysis were performed to supplement the results reported in "Zeolite-Templated Carbon Materials for High Pressure Hydrogen Storage" to assure reproducibility of the results, validate the templated structure of ZTCs, further analyze the micropore character of MSC-30 and ZTCs, and to probe differences in chemical bonding between MSC-30 and ZTCs that could clarify their significant difference in skeletal density.The correlation between BET surface area and excess hydrogen uptake across all temperatures and pressures in ZTCs and the other materials studied is central to the conclusions from this study. In addition to standard hydrogen adsorption/desorption measurements, we also include hydrogen cycling results to show full reversibility of hydrogen uptake and to verify that the experimental error in measurements is acceptable. Secondly, the BET method for characterizing the surface area of materials was supplemented by the Dubinin-Radushkevich method for determining microporous volume to determine the correlation between this value and excess hydrogen uptake at room temperature.Additional comparison of material properties of ZTC-3 and other ZTCs is important for validating the comparison of our high pressure results to those in the literature. Electron microscopy, both scanning (SEM) and transmission (TEM), was performed to show the similarity of ZTC-3 to "PFA-P7-H" synthesized by Ma et al. 38 , an approximately equivalent reference material to "P7(2)-H" of Nishihara et al. 16 Finally, some measurements were performed to determine if there were differences in sp 2 or sp 3 chemical bonding in ZTC-3 and MSC-30, including x-ray photolelectron spectroscopy (XPS), electron energy-loss spectroscopy (EELS), and solid-state 13 C nuclear magnetic resonance (NMR). The motivation for this additional work was elucidation of the nature of the different skeletal density between the two materials. However, no significant differences were detected that could account for the large difference in skeletal density. The results are consistent with those in the literature, for example by Yang et al. 33(XPS results) and Ma et al. 32 (NMR results). Hydrogen CyclingHydrogen uptake isotherms measured up to 30 MPa, using our newly constructed Sieverts apparatus specific to high pressure experiments, were cycled multiple times to ensure repeatability of the results. Hydrogen cycling in all materials studied was achieved without any loss of capacity on adsorption and desorption after many cycles, as expected for pure physisorbent materials. For example, three consecutive hydrogen adsorption/desorption cycles in ZTC-3 at 298 K are shown in Figure S1. The sample was degassed before cycling, as detailed in the Experimental Methods, but was not degassed in between cycles. Dubinin-Radushkevich Micropore VolumeNitrogen adsorption isotherms at 77 K were further analyzed to determine the Dubinin-Radushkevich (DR) micropore volume 21 of each sample. The DR method for treating the N 2 ...

Thermodynamic analyses of high pressure methane adsorption in shale are rarely reported because of the lack of a reliable approach for obtaining the true adsorption uptake from observed adsorption isotherms and the routinely used, oversimplified Clausius-Clapeyron (C-C) approximation. This work extends our previously proposed dual-site Langmuir adsorption model to calculate the isosteric heat of adsorption analytically from the observed adsorption isotherms for high pressure methane adsorption isotherms on Longmaxi shale from Sichuan, China (up to 27 MPa and 355.15 K). The calculated isosteric heat of adsorption considers both the real gas behavior of bulk methane and the adsorbed phase volume, which are neglected in the CC approximation. By this method, the temperature dependence as well as the uptake dependence of the isosteric heat can be readily investigated, where the former cannot be revealed using the CC approximation. The influence of the adsorbed phase and the gas behavior (real gas or ideal gas) on the isosteric heat of adsorption are also investigated, which shows that neglecting either the real gas behavior or the adsorbed phase volume always results in an overestimation of the isosteric heat of adsorption. In the Henry's law regime of low pressure and low adsorption uptake (and up to a surface occupancy of < 0.5), the isosteric heat of adsorption of methane on Longmaxi shale is approximately constant at 15-17 kJ/mol, but then decreases significantly at higher pressures. This work therefore justifies the method to obtain the true isosteric heat of adsorption for high pressure methane in shale, which lays the foundation for future investigations of the thermodynamics and heat transfer characteristics of the interaction between high pressure methane and shale.

Hydrogen uptake was measured for platinum doped superactivated carbon at 296 K where hydrogen spillover was expected to occur. High pressure adsorption measurements using a Sieverts apparatus did not show an increase in gravimetric storage capacity over the unmodified superactivated carbon. Measurements of small samples (∼0.2 g) over long equilibration times, consistent with the reported procedure, showed significant scatter and were not well above instrument background. In larger samples (∼3 g), the hydrogen uptake was significantly above background but did not show enhancement due to spillover; total uptake scaled with the available surface area of the superactivated carbon. Any hydrogen spillover sorption was thus below the detection limit of standard volumetric gas adsorption measurements. Due to the additional mass of the catalyst nanoparticles and decreased surface area in the platinum doped system, the net effect of spillover sorption is detrimental for gravimetric density of hydrogen.