A　thermal　nitridation　route　for　the　assembly　and　polymerization　of　molecular　triazine　units　to　heptazine-based　covalent　frameworks　has　been　successfully　established.　The　obtained　conjugated　carbon　nitride　polymers　feature　nanostructures　that　show　enhanced　photocatalytic　reactivity　for　hydrogen　production　under　visible　light　irradiation.　(c)　2015,　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.　All　rights　reserved.