A method for fabricating a composite gas separation module includes depositing a preactivated powder over a porous substrate; depositing a binder metal onto the preactivated powder; and depositing a dense gas-selective membrane to overlie the preactivated powder and binder metal, thereby forming the composite gas separation module. The preactivated powder can be, for example, selected from the group consisting of preactivated metal powders, preactivated metal oxide powders, preactivated ceramic powders, preactivated zeolite powders, and combinations thereof. The preactivated powder can be deposited, for example, from a slurry such as a water-based slurry. In some embodiments, the dense gas-selective membrane is a dense hydrogen-selective membrane.