Design and fabrication of hierarchically structured membranes with high proton conductivity is crucial to many energy-relevant applications including proton exchange membrane fuel cell (PEMFC). Here, a series of imidazole microcapsules (IMCs) with tunable imidazole group loading, shell thickness, and lumen size are synthesized and incorporated into a sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare composite membranes. The IMCs play two roles: i) Improving water retention properties of the membrane. The IMCs, similar to the vacuoles in plant cells, can render membrane a stable water environment. The lumen of the IMCs acts as a water reservoir and the shell of IMCs can manipulate water release. ii) They form anhydrous proton transfer pathways and low energy barrier pathways for proton hopping, imparting an enhanced proton transfer via either a vehicle mechanism or Grotthuss mechanism. In particular, at the relative humidity (RH) as low as 20%, the composite membrane exhibits an ultralow proton conductivity decline and the proton conductivity is one to two orders of magnitude higher than that of SPEEK control membrane. The enhanced proton conductivity affords the composite membrane an elevated peak power density from 69.5 to 104.5 mW cm − 2 in a single cell. Moreover, the application potential of the composite membrane for CO 2 capture is explored.
This work targets the area selective atomic layer deposition (AS-ALD) of TiN onto HfO 2 for use as the word line in a memory device. Unlike other patterning processes, AS-ALD eliminates etching steps and also allows for growth of patterned films with precise thickness control. This study investigates how AS-ALD differs on planar and nonplanar surfaces. Using a combination of X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy, we demonstrate a way to confer selectivity to a substrate using surface features. Self-assembled monolayers form defects at regions of high curvature, allowing nucleation of TiN films in ALD. This is in contrast to a treated planar surface with no features, which exhibits complete blocking of TiN up to a certain limit of ALD cycles.
The authors report the area-selective deposition of cobalt (II) oxide on polystyrene-patterned SiO2/Si and MgO(001) substrates at 180 °C by atomic layer deposition (ALD) using bis(N-tert butyl, N′-ethylpropionamidinato) cobalt (II) and water as coreactants. The patterned CoO films are carbon-free, smooth, and were reduced with atomic deuterium at 220 °C to produce Co metal patterns without shape deformation. CoO ALD is facile on starting surfaces that features hydroxyl groups favoring CoO nucleation and growth. Polystyrene (PS) is very effective in blocking ALD of CoO. The PS is patterned using UV-crosslinked 40 nm-thick PS films to generate μm-size features or using self-assembled 40 nm-thick polystyrene-block-polymethylmethacrylate (PS-b-PMMA) films to generate nm-size features. The unexposed PS in UV-crosslinked PS films is dissolved away with toluene, or the PMMA component in self-assembled PS-b-PMMA films is selectively removed by a plasma etch to expose the underlying oxide surface. The magnetic properties of the Co metal patterns grown by area-selective atomic layer deposition are presented.
H 2 O 2 and polarity are quite important in many physiological and pathological processes, and their relationship is complicated and obscure for researchers. Thus, it is vital and challenging to achieve simultaneous detection of H 2 O 2 and polarity in vivo. Herein, the first naphthalimide−triphenylamine-based dualsite fluorescent probe NATPA is developed for simultaneously imaging intracellular H 2 O 2 and polarity fluctuations. It exhibits excellent sensitivity (LOD = 44 nM), selectivity, and fast response (15 min) to H 2 O 2 and a superior capacity for detecting polarity upon the intramolecular charge transfer (ICT) effect. Besides, the probe displays low cytotoxicity and lipid droplet targeting and is further applied in imaging H 2 O 2 and polarity fluctuations in HepG2 and L-02 cells, so that NATPA is qualified to distinguish cancer cells from normal cells. This research contributes a new design principle for the construction of dual-site fluorescent probes for simultaneously detecting active molecules and polarity.
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