Spillover enhanced hydrogen uptake of Pt/Pd doped corncob-derived activated carbon with ultra-high surface area at high pressure

• Pore size distribution of CAC obviously varies with different doping content of Pt/Pd.
• Pd particles are easier to grow up than Pt particles on the surface of carbon.
• Metal clusters' formation inside pore channel enhances effectively spillover effects.
• Pt/Pd hybrid doping is more beneficial to atomic H's diffusion than pure Pt.

Corncob-derived activated carbon (CAC) was prepared by potassium hydroxide activation. The Pt/Pd-doped CAC samples were prepared by two-step reduction method (ethylene glycol reduction plus hydrogen reduction). The as-obtained samples were characterized by N2-sorption, TEM and XRD. The results show the texture of CAC is varied after doping Pt/Pd. The Pd particles are easier to grow up than Pt particles on the surface of activated carbon. For containing Pt samples, the pore size distributions are different from original sample and Pd loaded sample. The hydrogen uptake results show excess hydrogen uptake capacity on the Pt/Pd-doped CAC samples are higher than pure CAC at 298 K, which should be attributed to hydrogen spillover effects. The 2.5%Pt and 2.5%Pd hybrid doped CAC sample shows the highest hydrogen uptake capacity (1.65 wt%) at 298 K and 180 bar, The particle size and distribution of Pt/Pd catalysts could play a crucial role on hydrogen uptake by spillover. The total hydrogen storage capacity analysis show that total H2 storage capacities for all samples are similar, and spillover enhanced H2 uptakes of metal-doped samples could not well support total H2 storage capacity. The total pore volume of porous materials also is a key factor to affect total hydrogen storage capacity.