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In this work, a soft-lithographic approach to fabricate submicrometer metal organic framework (MOF)-based 2D photonic structures is described. Nanometric zeolitic imidazole framework material ZIF-8 (zinc) is chosen as the sensible MOF material because of its chemical stability and its vapor selective adsorption properties. Two different systems are fabricated: nanopatterned colloidal ZIF-8 homo- and ZIF-8/TiO2 heterostructures. Several features (stripes, squares, etc.) with dimensions of 200 nm are replicated on different substrates such as silicon, flexible plastics, and even aluminum cans, over relatively large surfaces (up to 1 cm2). In addition, the use of these photonic MOF-heterostructures as very low-cost sensing platforms compatible with smartphone technology is demonstrated. This method relies on the evaluation of the change in diffraction efficiency of the photonic MOF-patterns, induced by the MOF refractive index variation, which is simply detected by a charge coupled device (CCD) camera, as those integrated in smartphones, without need for complex optical instrumentations for transduction data processing. Performances of the sensors are first evaluated using isopropyl alcohol adsorption/desorption cycling as a model case. In addition, a 'real' environmental issue is tackled. Selective detection of styrene in presence of interfering water is demonstrated at concentrations below the human permissible exposure limit. In situ ellispometric analyses are also carried out in order to confirm the sensor performances and to propose a mechanism for styrene uptake into the nanoMOFs. [ABSTRACT FROM AUTHOR]

Stochastic Rotation Dynamics (SRD) is a mesoscale simulation technique that captures hydrodynamic couplings in simple and complex fluids. It can be used in various hydrodynamic regimes and it is not restricted to specific geometries. We show here that SRD using the collisional coupling approach to capture momentum transfer between the semi-implicit solvent and the explicit counterions, is able to describe electro-kinetic effects, i.e. coupled electrostatic and hydrodynamic phenomena occurring at charged solid–liquid interfaces. The method is first validated for electro-osmosis in the simple case of a slit pore without added salt, for which an analytical solution of the Helmholtz–Smoluchowski theory is known, in a physical regime where this mean-field theory is valid. We then discuss the predictions of SRD for electro-osmosis beyond the range of validity of the Helmholtz–Smoluchowski (or Poisson–Nernst–Planck) theory, in particular due to ion–ion correlations at the surface, to charge localisation on discrete sites at the solid surface and to surface charge heterogeneity, that all contribute to a reduction of the electro-osmotic flow. In order to disentangle these last two aspects, we also investigate at the mean-field level a simple system with alternate charged and neutral stripes, using lattice-Boltzmann electro-kinetics simulations. Overall, this work opens new perspectives for the use of SRD as a generic mesoscopic simulation method for soft matter problems, in particular under confinement, since in practice many interfaces between fluids and solids are charged. [ABSTRACT FROM PUBLISHER]

Self‐healing (SH) of (opto)electronic material damage can have a huge impact on resource sustainability. The rising interest in halide perovskite (HaP) compounds over the past decade is due to their excellent semiconducting properties for crystals and films, even if made by low‐temperature solution‐based processing. Direct proof of self‐healing in Pb‐based HaPs is demonstrated through photoluminescence recovery from photodamage, fracture healing and their use as high‐energy radiation and particle detectors. Here, the question of how to find additional semiconducting materials exhibiting SH, in particular lead‐free ones is addressed. Applying a data‐mining approach to identify semiconductors with favorable mechanical and thermal properties, for which Pb HaPs are clear outliers, it is found that the Cs2AuIAuIIIX6, (X = I, Br, Cl) family, which is synthesized and tested for SH. This is the first demonstration of self‐healing of Pb‐free inorganic HaP thin films, by photoluminescence recovery. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) are semiconductors with promising application in optoelectronic devices, particularly, in solar cell technologies. The chemical and electronic properties of MHPs at the surface and interfaces with adjacent layers dictate charge transfer within stacked devices and ultimately the efficiency of the latter. X‐ray photoelectron spectroscopy is a powerful tool to characterize these material properties. However, the X‐ray radiation itself can potentially affect the MHP and therefore jeopardize the reliability of the obtained information. In this work, the effect of X‐ray irradiation is assessed on Cs0.05MA0.15FA0.8Pb(I0.85Br0.15)3 (MA for CH3NH3, and FA for CH2(NH2)2) MHP thin‐film samples in a half‐cell device. There is a comparison of measurements acquired with synchrotron radiation and a conventional laboratory source for different times. Changes in composition and core levels binding energies are observed in both cases, indicating a modification of the chemical and electronic properties. The results suggest that changes observed over minutes with highly brilliant synchrotron radiation are likely occurring over hours when working with a lab‐based source providing a lower photon flux. The possible degradation pathways are discussed, supported by steady‐state photoluminescence analysis. The work stresses the importance of beam effect assessment at the beginning of XPS experiments of MHP samples. [ABSTRACT FROM AUTHOR]

2D photonic metal–oxide‐framework‐based homo‐ and hetero‐structures are fabricated by soft lithographic approaches. As shown by A. Cattoni, M. Faustini and co‐workers, these materials can be used as selective photonic sensing platforms. Detection of toxic vapors such as styrene are performed using an easy transduction method, compatible with smart‐phone camera technologies. [ABSTRACT FROM AUTHOR]