Synthesis　of　high-quality　carbon　nanosheets　with　superior　physicochemical　properties　is　of　particular　importance　for　environmental　and　catalytic　applications.　In　this　research,　carbon　nanosheets　with　tunable　porosity　were　successfully　synthesized　using　two-dimensional　(2D)　poly(m-phenylenediamine)　(PmPD)　as　precursor.　The　flat　polymer　precursor　was　acquired　by　oxidative　polymerisation　of　m-phenylenediamine　coupled　with　iron　ions　coordination,　which　confined　an　anisotropic　growth　of　polymer　within　the　2D　directions.　Moreover,　the　addition　of　H2O　after　the　polymerisation　is　able　to　indirectly　regulate　the　porosity　of　the　carbon　nanosheets.　The　carbon　nanosheets　with　controllable　porosity　realize　comparable　electrocatalytic　activity　for　oxygen　reduction　reaction　as　compared　with　commercial　Pt/C,　indicative　of　great　potential　to　serve　as　noble　metals　candidates　in　the　application　of　zinc/air　batteries.　©　2018　Elsevier　Inc.