Preparation and characterization of nickel-modified carbon cryogel beads with uniform particle size

Nickel-modified carbon cryogel beads (Ni/CCBs) with uniform particle size were successfully prepared using the syringe injection method, employing sol–gel polycondensation of a resorcinol–formaldehyde (RF) solution containing Ni acetate as a catalyst. This process was followed by solvent exchange, freeze-drying and carbonization in a nitrogen atmosphere. The effect of viscosity, which increased as the sol–gel polycondensation progressed, of the RF solution on both the particle size distributions of the Ni/CCB and the porous properties was investigated. The influence of Ni content in the initial reactants on the porous properties of the Ni/CCBs was also studied. Monodisperse Ni/CCBs could be obtained by injection during the initial reaction period, before the steep increase in the viscosity of the RF solution. The porous properties of the Ni/CCBs were independent of the viscosity of the RF solution. The BET surface area, micropore volume and mesopore volume of Ni/CCBs decreased with increased Ni content, whereas the macropore volume increased with increased Ni content. The size of the Ni nanoparticles dispersed in the carbon matrix of Ni/CCBs was confirmed to range from 30 to 60 nm.