Lithium-sulfur (Li-S) secondary batteries with sulfur cathodes and theoretical energy density of ∼2600 Wh/kg, are promising high energy-density system for next-generation electric-vehicles (EVs) potentially mitigating the gravimetric and volumetric energy density limitations of existing lithium-ion (Li-ion) batteries. Herein, a chemically synthesized sulfonic acid-based complex framework material (CFM) termed as (SCFM), was used as sulfur host (S-SCFM) to prevent polysulfide dissolution in Li-S batteries. The S-SCFM based CFM cathodes show an initial capacity of 1190 mAh/g and a capacity of 1044 mAh/g after 100 cycles. In addition, the S-SCFM based CFM cathodes exhibited good cycling stability with a minimal fade rate of ∼0.0012% per cycle. XPS analysis of the cycled separators with the S-SCFM electrodes shows complete absence of polysulfide species after 100 charge-discharge cycles. It was also identified that the SCFM based CFM chemically binds sulfur via -C-S- linkages thereby exhibiting an affinity for the polysulfide species formed during the charge-discharge cycles. As a result, the SCFM based CFM prevent polysulfide species from dissolving and diffusing into the electrolyte. A thorough understanding of these engineered SCFM based CFM sulfur host in Li-S battery outlined herein will be vital in designing promising sulfur hosts for next generation sulfur cathodes in Li-S batteries.

Identification of low cost, highly active, durable completely noble metal-free electro-catalyst for oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells, oxygen evolution reaction (OER) in PEM based water electrolysis and metal air batteries remains one of the major unfulfilled scientific and technological challenges of PEM based acid mediated electro-catalysts. In contrast, several non-noble metals based electro-catalysts have been identified for alkaline and neutral medium water electrolysis and fuel cells. Herein we report for the very first time, F doped Cu_1.5Mn_1.5O₄, identified by exploiting theoretical first principles calculations for ORR and OER in PEM based systems. The identified novel noble metal-free electro-catalyst showed similar onset potential (1.43 V for OER and 1 V for ORRvsRHE) to that of IrO₂and Pt/C, respectively. The system also displayed excellent electrochemical activity comparable to IrO₂for OER and Pt/C for ORR, respectively, along with remarkable long term stability for 6000 cycles in acidic media validating theory, while also displaying superior methanol tolerance and yielding recommended power densities in full cell configurations.

Recent developments in tissue engineering approaches frequently revolve around the use of three-dimensional scaffolds to function as the template for cellular activities to repair, rebuild and regenerate damaged or lost tissues. While there are several biomaterials to select as three-dimensional scaffolds, it is generally agreed that a biomaterial to be used in tissue engineering needs to possess certain material characteristics such as biocompatibility, suitable surface chemistry, interconnected porosity, desired mechanical properties and biodegradability. The use of naturally derived polymers as three-dimensional scaffolds has been gaining widespread attention owing to their favourable attributes of biocompatibility, low cost and ease of processing. This paper discusses the synthesis of various polysaccharide-based, naturally derived polymers, and the potential of using these biomaterials to serve as tissue engineering three-dimensional scaffolds is also evaluated. In this study, naturally derived polymers, specifically cellulose, chitosan, alginate and agarose, and their composites, are examined. Single-component scaffolds of plain cellulose, plain chitosan and plain alginate as well as composite scaffolds of cellulose–alginate, cellulose–agarose, cellulose–chitosan, chitosan–alginate and chitosan–agarose are synthesized, and their suitability as tissue engineering scaffolds is assessed. It is shown that naturally derived polymers in the form of hydrogels can be synthesized, and the lyophilization technique is used to synthesize various composites comprising these natural polymers. The composite scaffolds appear to be sponge-like after lyophilization. Scanning electron microscopy is used to demonstrate the formation of an interconnected porous network within the polymeric scaffold following lyophilization. It is also established that HeLa cells attach and proliferate well on scaffolds of cellulose, chitosan or alginate. The synthesis protocols reported in this study can therefore be used to manufacture naturally derived polymer-based scaffolds as potential biomaterials for various tissue engineering applications.