Template-free routes to porous inorganic materials

New approaches to solid-state reactivity have allowed us to develop unusual routes to porous inorganic materials. This article describes our recent work on template-free routes involving the selective leaching of one phase from a two-phase composite to form porous oxides. Subsequent reactions have been developed to yield porous metals, conformal coatings, and hierarchically porous materials. Pores can also be generated through simple redox processes in transition-metal oxides; such redox cycling allows mesopores to be produced in a regenerative process in a material which is already macroporous.