Enhanced hydrogen storage on Pt-doped carbon by plasma reduction

Hydrogen adsorption properties of a superactived carbon (AX-21) doped with Pt nanoparticles by using plasma reduction were studied and were compared with that by using traditional H₂ reduction. The hydrogen storage capacity was significantly increased by plasma reduction. The H₂ storage capacity on Pt-doped AX-21 at 298 K and 10 MPa was increased from 1.19 wt % (by H₂ reduction) to 1.46 wt % on the sample obtained by plasma reduction. The plasma-reduced sample produced 1.5?3 nm Pt particles that were highly dispersed on carbon, and most interestingly, the metal particles were recessed into the carbon substrate. Both isosteric heats of adsorption and the activation energies for spillover were decreased by plasma reduction, which was evidence that the energy barrier for H spillover was lowered by plasma treatment, resulting in faster rates as well as higher spillover capacities. Mechanisms for plasma reduction and for edge recession of the metal particles into carbon are proposed.