The rising worldwide energy demands and the difficulty in developing novel clean energies have greatly stimulated the exploitation of shale gas. Understanding adsorption and diffusion of shale gas under different geological depths is an important issue. In this work, we use grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations to investigate adsorption and diffusion behavior of shale gas (main component is methane) in a modeled shale in different burial depths up to 6 km. To examine the diffusion of shale gas, the equilibrium configuration of GCMC simulation is used as initial inputs for further MD simulations. The results indicate that the capacity of shale gas increases slightly with the depth, while the diffusion coefficient of shale gas in the shale matrix decreases with the increase of the pressure. Interestingly, a maximum diffusion coefficient of methane appears in a burial depth of 5 km. By cooperatively considering adsorption and diffusion results, we propose that the optimum operating condition is under a depth of 3−5 km. Moreover, we find that, when the basal spacing increases to 100 Å, the diffusion coefficients obtain an improvement of 80 times compared to the case with basal spacing of 8 Å, which provides useful guidance for exploitation of shale gas.

With rapid advances of perovskite light-emitting diodes (PeLEDs), the large-scale fabrication of patterned PeLEDs towards display panels is of increasing importance. However, most state-of-the-art PeLEDs are fabricated by solution-processed techniques, which are difficult to simultaneously achieve high-resolution pixels and large-scale production. To this end, we construct efficient CsPbBr3 PeLEDs employing a vacuum deposition technique, which has been demonstrated as the most successful route for commercial organic LED displays. By carefully controlling the strength of the spatial confinement in CsPbBr3 film, its radiative recombination is greatly enhanced while the nonradiative recombination is suppressed. As a result, the external quantum efficiency (EQE) of thermally evaporated PeLED reaches 8.0%, a record for vacuum processed PeLEDs. Benefitting from the excellent uniformity and scalability of the thermal evaporation, we demonstrate PeLED with a functional area up to 40.2 cm2 and a peak EQE of 7.1%, representing one of the most efficient large-area PeLEDs. We further achieve high-resolution patterned perovskite film with 100 μm pixels using fine metal masks, laying the foundation for potential display applications. We believe the strategy of confinement strength regulation in thermally evaporated perovskites provides an effective way to process high-efficiency and large-area PeLEDs towards commercial display panels.

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The Ordos Block is a large but poorly exposed crustal segment in the western part of the North China Craton. Little is known about its Precambrian basement rocks and their evolution because of an extensive cover by younger sedimentary rocks. We report SHRIMP zircon ages and Hf-in-zircon isotopic compositions for five samples recovered from drill holes that penetrated into the Ordos basement. Based on these data, two age groups of rocks can be distinguished: an early Paleoproterozoic group that is represented by one sample from the northern margin of the Ordos Block and a late (or middle-late) Paleoproterozoic group consisting of the remaining four samples. The early Paleoproterozoic sample contains zircon cores and metamorphic rims with ages of >2.4 Ga and >2.28 Ga, respectively. The cores have Hf (t) values of ؊8.8 to 6.2 and Hf crustal model ages of 2606 to 3221 Ma. The remaining rocks of late (or middle-late) Paleoproterozoic age contain zircons that may also show a core-rim structure, but with the cores having ages of ϳ2.08 Ga and the metamorphic rims recording ages of ϳ1.9 Ga. The zircon cores have Hf (t) values of ؊9.1 to 10.1, and Hf crustal model ages of 2039 to 3068 Ma. Combined with data from earlier studies, we draw the conclusion that late Paleoproterozoic metasedimentary rocks are widespread in the Ordos basement. There is no evidence from our samples of an Archean component, and this calls into question the prevailing view that the Ordos basement is an Archean cratonic block. The fact that the Ordos basement was involved in a widespread late Paleoproterozoic tectono-thermal event indicates that most current models for the tectonic evolution of the western portion of the North China Craton need to be revised.