Investigation on the existence of optimum interlayer distance for H ₂ uptake using pillared-graphene oxide

In order to prove the existence of an optimum interlayer distance for H₂ uptake, we have obtained H₂ isotherms with respect to the interlayer distance of pillared-graphene oxide (GO) at 1.0 bar and 77 K. Interlayer distances of GO were changed by intercalation of three kinds of diaminoalkanes with a different number of carbon atoms (NH₂(CH ₂)_nNH₂, n = 2, 6, 10) as pillars and changing the subsequent thermal annealing conditions. We found an optimum GO interlayer distance for maximum H₂ uptake at 6.3 similar to the predicted distance from first-principles calculations for graphitic materials, and the value obtained from thermally modulated GO. Our results experimentally corroborate the existence of an optimum interlayer distance and demonstrate the importance of an interlayer distance for the design of materials for H ₂ storage.