Preparation of porous carbon with high dispersion of Ru nanoparticles by sol–gel method and its application in hydrogen storage

Abstract

Nano-Ru/porous carbon composites were prepared by Ru/aerogels which were made through a reaction of resorcinol, formaldehyde and RuCl₃·3H₂O. The specific surface area (SSA) measurement showed that there was an SSA maximum with the increase of Ru loading. The sample R_Ru = 5 (mol percent) obtained the largest SSA value of 1970 m² g⁻¹ and the most homogeneous distribution of Ru nanoparticles on the porous carbon surface. It also obtained the highest hydrogen adsorption value of 0.8 wt% (7.5 MPa) and 4.1 wt% (4 MPa) at 298 and 77 K respectively. Considering the H₂ compressed within the pores, the corresponding total value reached up to 1.4 wt% (P = 7.5 MPa) and 6.3 wt% (P = 6.5 MPa) at 298 and 77 K respectively. Compared with porous carbon, the Ru/porous carbon composites had an obvious adsorption increase under the same SSA conditions at 298 K, which were contributed by the hydrogen spillover of Ru. The calculated contribution rate for hydrogen adsorption was 38%. However, the spillover effect also brought a hysteresis phenomenon during hydrogen desorption since the hydrogen spilled from the hydride into the carbon matrix needed a lower pressure to move and release.