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Preparation of Ce3+ doped ZnO nanoparticles via a wet chemical method and analysis of their local structure
No full textPhase Equilibrium Data and Phase Behavior in Formation Systems of Semiclathrate Hydrates Formed with Partly Asymmetric Quaternary Ammonium Salts under Methane, Carbon Dioxide, and Nitrogen Gas Pressure
No full textSemiclathrate hydrates are water-based crystalline host–guest materials which consist of water and large ionic substances. To expand their unique functions, investigation into asymmetric quaternary ammonium salts, i.e., n-butyl chains of tetra-n-butylammonium (TBA or N4444 where N and 4 denote nitrogen and n-butyl group, respectively) cation is partly substituted by other group, is necessary. In this study, we report the three-phase (gas–hydrate–liquid) equilibrium data in the systems of (N3444Cl or N4445Cl) + (CH4, CO2 or N2) + H2O up to 10 MPa of the pressure, where 3 and 5 denote n-propyl and n-pentyl, respectively. A total of 99 equilibrium datasets were obtained with aqueous compositions with 0.1, 0.2 and 0.3 of salt mass fraction. Both of N3444Cl and N4445Cl promoted formation conditions of CH4, CO2 and N2 gas hydrates. N3444Cl partly acted as an inhibitor for pure CH4 and CO2 hydrates under some conditions, and it also showed polymorphic phase behavior. Comparison with the literature data for other ionic guests was made. The present findings help understanding of the phase behavior of the semiclathrate hydrates, which can be applied for further development of applications based on these materials
Nanostructural design of flexible mesoporous hydrogel electrodes via colloidal electrochemical deposition for highly efficient oxygen evolution reaction
No full textWater electrolysis is a core technology for converting renewable energy into hydrogen and is useful for energy storage and transportation. Porous electrodes can efficiently promote the oxygen evolution reaction (OER) because of their high surface area; however, the generated bubbles block the electrode surface and reduce the number of reaction sites. Here, we demonstrate flexible mesoporous hydrogel electrodes with more than 90% high porosity prepared by the colloidal electrochemical deposition of hybrid cobalt hydroxide nanosheets (Co-ns) as promising new materials for porous OER electrodes in alkaline media, combining large surface area with high mass transport. The pore size of the flexible mesoporous hydrogel electrodes was controlled in the range of 25–45 nm by controlling the lateral size of the Co-ns. The pore surfaces of the flexible mesoporous hydrogel electrodes with larger pore sizes were utilized more efficiently in the depth along the thickness direction, demonstrating higher mass transportation. Colloidal electrochemical deposition is also useful for constructing hierarchical structures, such as bilayer electrodes combining differently sized mesopores, placing larger pores with high mass transport on the top layer and small pores with high surface area on the bottom layer, thereby achieving a higher OER current density than monolayer electrodes. Flexible mesoporous hydrogel electrodes, with facile control over mesopores and hierarchical structures, show great potential as new forms of mesoporous electrodes for water electrolysis
Reprecipitation-driven access to solvates and solvent-free crystals: achieving two-solvent-mediated vapochromic luminescence
Full text linkVapochromic luminescent organic crystals have attracted significant attention in recent years for their potential in environmental monitoring and solvent sensing. Restoring the original emission color after vapor-induced changes typically requires additional stimuli such as heating, vacuum treatment, or prolonged exposure to air. Herein, three types of microcrystals obtained by reprecipitation of an organic luminophore exhibit two-solvent-mediated vapochromic luminescence, in which their emission color can be reversibly modulated by sequential exposure to two distinct organic solvent vapors. Interconversion between a chloroform-including green-emissive crystal and a solvent-free yellow-emissive crystal is achieved by exposure to ethyl acetate and chloroform vapors, respectively. Yellow- and orange-emissive solventfree crystals that share the same crystal structure but differ in preferred orientation convert to green-emissive crystals upon exposure to chloroform vapor. Notably, both crystals revert to their original states upon exposure to ethyl acetate vapor, indicating retention of the initial crystal memory