Enhanced catalytic activity in hydrogen production from hydrolysis of sodium borohydride using starch hydrogel-CoNi bimetallic alloys

Abstract

In this article, starch hydrogel was successfully prepared using a citric acid cross-linking method and was used as a template to synthesize starch hydrogel-CoNi bimetallic alloys by the in situ reduction in Co2+ Ni2+ ions using NaBH4 as the reducing agent in the presence of the starch hydrogel network. The starch hydrogel-CoNi bimetallic alloys were simply isolated by filtration and also characterized by SEM, TEM, TGA, FTIR and XRD, respectively. The catalytic activity of starch hydrogel-CoNi bimetallic alloys was used as a catalyst in the hydrogen production from the hydrolysis of NaBH4 in the presence of alkaline solution. The variables affecting on the hydrolysis of NaBH4 such as the initial CoNi molar ratio, initial NaOH concentration, catalyst amount, initial NaBH4 concentration and reaction temperature were examined. The activation energy (Ea), the activation enthalpy (∆H#) and the activation entropy (∆S#) were found to be 36.24 kJ mol−1, 37.75 kJ mol−1 and − 125.23 kJ mol−1 K−1, respectively. The catalyst can be used up to 5 times with 100% conversion, and the catalyst was remained 68% activity after storing 15 days. This approach offers a great potential to utilize starch hydrogel acting as a biocompatible material for a large-scale synthesis of bimetallic alloys for various applications in catalysis.