Three Dimensionally Ordered Mesoporous Carbon as a Stable,High‐Performance Li–O2 Battery Cathode

Enabled by the reversible conversion between Li₂O₂ and O₂, Li–O₂ batteries promise theoretical gravimetric capacities significantly greater than Li‐ion batteries. The poor cycling performance, however, has greatly hindered the development of this technology. At the heart of the problem is the reactivity exhibited by the carbon cathode support under cell operation conditions. One strategy is to conceal the carbon surface from reactive intermediates. Herein, we show that long cyclability can be achieved on three dimensionally ordered mesoporous (3DOm) carbon by growing a thin layer of FeO_x using atomic layer deposition (ALD). 3DOm carbon distinguishes itself from other carbon materials with well‐defined pore structures, providing a unique material to gain insight into processes key to the operations of Li–O₂ batteries. When decorated with Pd nanoparticle catalysts, the new cathode exhibits a capacity greater than 6000 mAh g_carbon⁻¹ and cyclability of more than 68 cycles.     

Material‐Efficient Microfluidic Platform for Exploratory Studies of Visible‐Light Photoredox Catalysis

We present an automated microfluidic platform for in‐flow studies of visible‐light photoredox catalysis in liquid or gas–liquid reactions at the 15 μL scale. An oscillatory flow strategy enables a flexible residence time while preserving the mixing and heat transfer advantages of flow systems. The adjustable photon flux made possible with the platform is characterized using actinometry. Case studies of oxidative hydroxylation of phenylboronic acids and dimerization of thiophenol demonstrate the capabilities and advantages of the system. Reaction conditions identified through droplet screening translate directly to continuous synthesis with minor platform modifications.     

Inhibition of Pathogen Adhesion by Bacterial Outer Membrane‐Coated Nanoparticles

Anti‐adhesion therapies interfere with the bacterial adhesion to the host and thus avoid direct disruption of bacterial cycles for killing, which may alleviate resistance development. Herein, an anti‐adhesion nanomedicine platform is made by wrapping synthetic polymeric cores with bacterial outer membranes. The resulting bacterium‐mimicking nanoparticles (denoted “OM‐NPs”) compete with source bacteria for binding to the host. The “top‐down” fabrication of OM‐NPs avoids the identification of the adhesins and bypasses the design of agonists targeting these adhesins. In this study, OM‐NPs are made with the membrane of Helicobacter pylori and shown to bind with gastric epithelial cells (AGS cells). Treatment of AGS cells with OM‐NPs reduces H. pylori adhesion and such anti‐adhesion efficacy is dependent on OM‐NP concentration and its dosing sequence.     

A Ternary Solvent Method for Large‐Sized Two‐Dimensional Perovskites

Recent reports demonstrate that a two‐dimensional (2D) structural characteristic can endow perovskites with both remarkable photoelectric conversion efficiency and high stability, but the synthesis of ultrathin 2D perovskites with large sizes by facile solution methods is still a challenge. Reported herein is the controlled growth of 2D (C₄H₉NH₃)₂PbBr₄ perovskites by a chlorobenzene‐dimethylformide‐acetonitrile ternary solvent method. The critical factors, including solvent volume ratio, crystallization temperature, and solvent polarity on the growth dynamics were systematically studied. Under optimum reaction condition, 2D (C₄H₉NH₃)₂PbBr₄ perovskites, with the largest lateral dimension of up to 40 μm and smallest thickness down to a few nanometers, were fabricated. Furthermore, various iodine doped 2D (C₄H₉NH₃)₂PbBr_x I_4−x perovskites were accessed to tune the optical properties rationally.     

Exploring Lead‐Free Hybrid Double Perovskite Crystals of (BA)2CsAgBiBr7 with Large Mobility‐Lifetime Product toward X‐Ray Detection

Halide double perovskites have recently bloomed as the green candidates for optoelectronic applications, such as X‐ray detection. Despite great efforts, the exploration of promising organic–inorganic hybrid double perovskites toward X‐ray detection remains unsuccessful. Now, single crystals of the lead‐free hybrid double perovskite, (BA)₂CsAgBiBr₇ (BA⁺ is n‐butylammonium), featuring the unique 2D multilayered quantum‐confined motif, enable quite large μτ (mobility‐lifetime) product up to 1.21×10^?3 cm² V^?1. This figure‐of‐merit realized in 2D hybrid double perovskites is unprecedented and comparable with that of CH₃NH₃PbI₃ wafers. (BA)₂CsAgBiBr₇ crystals also exhibit other intriguing attributes for X‐ray detection, including high bulk resistivity, low density of defects and traps, and large X‐ray attenuation coefficient. Consequently, a vertical‐structure crystal device under X‐ray source yields a superior sensitivity of 4.2 μC Gy_air^?1 cm^?2.