H2 generation from NaBH4 and NH3BH3 using metal catalysts prepared within p(VI) capsule particles

•P(VI) colloidal capsule from template removal•P(VI) capsule for in situ metal nanoparticle preparation•P(VI)-M catalysts for NaBH4 and NH3BH3 hydrolysis•Hydrogen production via microgel composite catalyst systems

Poly(vinyl imidazole) (p(VI)) and poly(vinyl imidazole)-silica (p(VI)-Si) were synthesized using a microemulsion polymerization technique, and capsules of p(VI) (cap-p(VI)) were prepared from p(VI)-Si particles using HF treatment to remove the silica core. Metal nanoparticles such as Co, Ni and Cu were prepared inside p(VI)-based particles and used as catalysts in hydrogen production from the hydrolysis of NaBH4 and BH3NH3. A variety of parameters including polymeric particle morphology, metal catalyst types, NaOH concentration, hydrolysis temperature, and the number of metal loading-reduction cycles were investigated for their effect on catalytic performance in the hydrolysis of chemical hydrides. The activation energy, enthalpy, and entropy of NaBH4 and BH3NH3 hydrolysis catalyzed by Co nanoparticles were calculated as 24.60 kJ mol− 1, 21.45 kJ mol− 1, and − 161.59 kJ mol− 1 K− 1 for NaBH4 and 51.58 kJ mol− 1, 47.85 kJ mol− 1, and − 147.46 kJ mol− 1 K− 1 for BH3NH3. The BET surface area, pore volume and pore width of p(VI)-based particles were also measured and surface area was 36.79 m2/g, 89.77 m2/g and 52.78 m2/g for p(VI), p(VI)-Si and cap-p(VI) particles, respectively.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide