Co nanoparticle decorated magnetic core, polymeric ionic liquid shell composites for H2 production

• Magnetic ferrites coated with silica and polymeric IL embedding Co MNP
• Magnetic PIL composite for fast H2 generation from NaBH4 hydrolysis
• Controllable H2 generation via mag@SiO2@p(4-VP)+ C4@Co composites
• Lowest Ea via mag@SiO2@p(4-VP)+ C4@Co composites

Here, firstly iron oxide (Fe3O4) nanoparticles (NPs) were prepared and coated with silica-containing vinyl groups, and then a poly(4-vinyl pyridine) p(4-VP) polymeric shell was synthesized around the silica-coated magnetic particles by micro emulsion polymerization technique (M@p(4-VP)). The magnetic polymeric ionic liquid (PIL) particles: M@p(4-VP)+ C2, M@p(4-VP)+ C4 and M@p(4-VP)+ C6, were then prepared by modifying M@p(4-VP) with 1,2-dibromoethane (DBE), 1,4-dibromobutane (DBB) and 1,6-dibromohexane, respectively. The magnetic PIL particles were used as template for Co metal nanoparticles (MNPs) and, M@p(4-VP)+ C2@Co, M@p(4-VP)+ C4@Co and M@p(4-VP)+ C6@Co were created as magnetic PIL-Co composite catalyst systems. The prepared magnetic PIL-Co composite catalyst systems were used as catalysts in H2 generation from hydrolysis of NaBH4. Various parameters such as the type of PIL template, the concentration of NaOH, the number of metal ion loading reducing processes (Co amounts), the reusability, and the hydrolysis reaction temperature were investigated for their effect on H2 production. Among the prepared PIL-metal composites, M@p(4-VP)+ C4 particles contained 504.6 mg g− 1 Co after 4 metal ion loading-reducing cycles. M@p(4-VP)+ C4@Co particles exhibited excellent catalytic activity in H2 generation from the hydrolysis of NaBH4 and their hydrogen generation rate (HGR) and Turn Over Frequency (TOF) were found as 8.46 ± 0.17 (L H2) (g of Co min)− 1 and 20.79 ± 0.10 and 10.43 ± 0.23 (mol H2) (mol of Co min)− 1, higher than most published data. Also, a very low activation energy (Ea = 22.8 ± 0.8 kJ mol− 1) was calculated for H2 generation for the hydrolysis of NaBH4 catalyzed by M@p(4-VP)+ C4@Co in comparison to similar studies.

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