A novel p(AAm-co-VPA) hydrogel for the Co and Ni nanoparticle preparation and their use in hydrogel generation from NaBH4

A novel bulk poly(acrylamide-co-vinyl phosphonic acid) (p(AAm-co-VPA)) hydrogels were synthesized via a photo polymerization technique in macro dimension. Ni and Co nanoparticles inside p(AAm-co-VPA) hydrogel were also prepared by reduction of the metal ions loaded into the hydrogel network from the corresponding metal salt solution in water. The reduction of these bound metal ions within hydrogel matrices were done by treating hydrogel-laden metal ions with NaBH4 to produce novel hydrogel-metal composite catalyst systems. Furthermore, these soft hydrogel composite catalyst systems were employed in the generation of hydrogen from the hydrolysis of sodium boron hydride (NaBH4) in a basic medium. Thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS) measurements were employed to determine the metal particle content of p(AAm-co-VPA)-M (M: Co, Ni) composite hydrogels. The effects of different parameters such as the amount of catalyst, the reaction temperature, the type of the metal, the initial concentration of NaBH4 and reusability of the prepared catalyst systems were investigated, and the activation energy for hydrolysis of NaBH4 by p(AAm-co-VPA) was found as 23.68 kЈ/mol.