A soft anionic hydrogel reactor for silver nanoparticle preparation and use in H2 production, 4-nitrophenol reduction and alcohol oxidation

Poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS) hydrogels were synthesized via free radical polymerization reaction technique under mild reaction conditions. The chemical structure of synthesized p(AMPS) anionic macroporous hydrogel was confirmed by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM). Synthesized hydrogels were used as template for in situ metal nanoparticle preparation by using Ag(CH3COO) in H2O. Metal nanoparticles embedded p(AMPS)-Ag were visualized by TEM. The metal content of composites was estimated via atomic absorption spectroscopy (AAS). This metal-nanoparticle porous hydrogel composite was employed in the reduction of 4-nitrophenol and H-2 generation from hydrolysis of sodium borohydride (NaBH4). The activation energies, enthalpy, and entropy for 4-NP reduction and NaBH4 hydrolysis catalyzed by composite were determined. P(AMPS)-Ag composite was also used as catalyst in the aerobic oxidation of alcohols by emphasizing the effects of different parameters such as temperature, substituent effect, etc. Finally, the catalysts were easily recovered from the reaction media and it could be re-used for the other four runs without significant loss of activity.