Abstract
Macroporous p(2-hydroxyethyl methacrylate) p(HEMA) cryogel was synthesized at 18°C via cryopolymerization technique and chemically modified with a quaternization agent (QA), 3-chloro-2-hydroxypropyl trimethyl ammonium chloride in basic medium to produce Q-p(HEMA). Then superporous p(HEMA) cryogel was used as template for in situ Co and Ni metal nanoparticle preparation and used as soft reactors in H2 generation reactions from hydrolysis of NaBH4. To increase the catalyst contents of the cryogel composites, multiple metal ion loading and reduction steps were carried out for faster H2 generation from the hydrolysis reaction. The effects of several parameters, such as number of reloading-reduction cycles (1st, 2nd and 3rd), metal nanoparticle types, concentration of NaBH4, alkalinity of reaction medium, and temperature on the H2 generation reactions were investigated. It was found that the 3rd time Co(II) loaded-reduced Q-p(HEMA)-Co cryogel composite is highly active as the turn over frequency (TOF) and the hydrogen generation rate (HGR) values were 62.9±1.8 (molH2) (mol catalyst min)−1 and 26,641.0±3.6 (mlH2) (min)−1 (g of M)−1 at 70°C which is even better than the fastest known catalyst, ruthenium.
