▎ 摘　　要

Hydrogen is an excellent energy carrier free of carbon dioxide emission, but safe and efficient storage of hydrogen has been a bottleneck for the commercial use of hydrogen as a fuel. Here, we present a strategy based on simple thermodynamic principles that the density of a gas residing in a potential well increases exponentially relative to the ambient gas by the corresponding Boltzmann factor. This mechanism allows for enormously enhanced H-2 storage in the form of delocalized gas permeating throughout the void space of a material, in contrast to conventional storage localized to specific adsorption sites. We create mesoporous graphene oxide that provides a two-dimensional potential well and efficient hydrogen diffusion pathways. The gravimetric storage density measured with quartz-crystal microbalance reaches 4.65 wt% reproducibly at a modest pressure of 40 atm at room temperature. Our work demonstrates the attainability of the long-standing goal of room-temperature hydrogen storage. (C) 2016 Elsevier Ltd. All rights reserved.