Muhammad Sohail Riaz

Abstract Highly reversible plating/stripping in aqueous electrolytes is one of the critical processes determining the performance of Zn‐ion batteries, but it is severely impeded by the parasitic side reaction and dendrite growth. Herein, a novel electrolyte engineering strategy is first proposed based on the usage of 100 mM xylitol additive, which inhibits hydrogen evolution reaction and accelerates cations migration by expelling active H 2 O molecules and weakening electrostatic interaction through oriented reconstruction of hydrogen bonds. Concomitantly, xylitol molecules are preferentially adsorbed by Zn surface, which provides a shielding buffer layer to retard the sedimentation and suppress the planar diffusion of Zn 2+ ions. Zn 2+ transference number and cycling lifespan of Zn ∥ Zn cells have been significantly elevated, overwhelmingly larger than bare ZnSO 4 . The cell coupled with a NaV 3 O 8 cathode still behaves much better than the additive‐free device in terms of capacity retention.

One-dimensional materials favoring efficient charge transfer have attracted enormous attentions. Here cobalt nanochains are prepared by a direct-current (DC) arc-discharge method under the gaseous mixture of He and H2. The Co nanochains can range up to several micrometers. When H2 is replaced by CO2, the sample shows a phase evolution from Co nanochains to CoO nanocubes. The ratio of CoO/Co can be effortlessly altered by varying the partial pressure of CO2 in the reaction gas mixture. CoO nanocubes are attained in the pure CO2. The prepared samples are explored as catalyst for oxygen evolution reaction (OER). The catalytic activity is highly dependent on the phase proportion of Co and CoO. The sample prepared under CO2:He = 1:7 unveils the optimal OER performance with an onset point of 1.50 V versus reversible hydrogen electrode (RHE) and an overpotential of 350 mV at 10 mA cm–2. The high OER performance can be attributed to synergistic effect and charge transfer process between Co and CoO. Co can inject electrons into CoO, which manipulates the work function of CoO to make it more suitable for oxygen evolution. The good OER performance can also be ascribed to the defective structure of CoO. The CoO/Co composite shows good robustness with less than 8% current loss throughout the long-term test.

Abstract The aim of this study was to develop a cheap, pH‐sensitive enteric coating of aspirin with biocompatible polymers. A novel approach was used to develop enteric coating from chitosan (CS) and poly(vinyl alcohol) (PVA). Solutions of CS and PVA (5 : 1 mol ratio) were mixed and selectively crosslinked with tetraethoxysilane. IR analysis confirmed the presence of the incorporated components and the existence of siloxane linkages between CS and PVA. The crosslinking percentage and thermal stability increased with increasing amount of crosslinker. The response of the developed coating in different media, such as water, pH (nonbuffer and buffer), and ionic media showed hydrogel properties. All hydrogels showed low swelling in acidic and basic pH media, whereas maximum swelling was exhibited at neutral pH. This pH sensitivity of the hydrogel has been exploited as enteric coating for commercial aspirin tablets. The dissolution test of enteric‐coated aspirin tablet in simulated gastric fluid (pH 1.2) showed 7.11% aspirin release over a period of 2 h, whereas a sustained release of remaining aspirin (83.25%) was observed in simulated intestinal fluid (pH 6.8). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012