an individual fuel permeation on the 1-?m-thick g-C3N4 membrane at space temperature and 1??bar. The inset exhibits the gas selectivity for H2 about other gases. b Permeance and separation elements on the one-?m-thick g-C3N4 membranes within the equimolar mixed-fuel permeation at space temperature and one??bar. Inset demonstrates the kinetic diamet