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A direct borohydride fuel cell (DBFC) employing a poly (vinyl alcohol) hydrogel membrane electrolyte (PHME) is reported. The DBFC employs an AB 5 Misch metal alloy as anode and a goldplated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous acidified solution of hydrogen peroxide as oxidant. Room temperature performances of the PHME-based DBFC in respect of peak power outputs; ex-situ cross-over of oxidant, fuel, anolyte and catholyte across the membrane electrolytes; utilization efficiencies of fuel and oxidant, as also cell performance durability are compared with a similar DBFC employing a Nafion ® -117 membrane electrolyte (NME). Peak power densities of ~30 and ~40 mW cm -2 are observed for the DBFCs with PHME and NME, respectively. The crossover of NaBH 4 across both the membranes has been found to be very low. The utilization efficiencies of NaBH 4 and H 2 O 2 are found to be ~24 and ~59%, respectively for the PHME-based DBFC; ~18 and ~62%, respectively for the NME-based DBFC. The PHME and NME-based DBFCs exhibit operational cell potentials of ~1⋅2 and ~1⋅4 V, respectively at a load current density of 10 mA cm -2 for ~100 h.

This paper describes a review of the state-of-the-art research carried on the fresh and hardened properties of Alkali Activated Binders and Concretes. Though, many research have been carried out in the recent times on alkali activated binders, few key parameters still remain unattended, that restricts the commercial application of AAMs to the general construction activities. Fresh properties, mechanical strength and durability performance of Alkali activated concrete with various Alumino silicates as base materials is mentioned. An essential parameter of Alkali activated concrete is the concentration of alkaline solution on which various properties like mechanical strength, setting time and durability depends. Influence of wide range of concentrations from 6 to 16 M on these properties are studied and reported in this paper. This paper mainly concentrates on properties of readily available base materials such as Fly ash and Slag and the means to improve their performance through the use of various industrial and agro-based byproducts as additives. Problems pertaining to practical applicability of AAMs to general construction activities are also highlighted.