Abstract:　Porous　carbons　with　large　surface　areas,　abundant　mesopores　and　weak　base　sites　are　promising　materials　for　the　capture　and　conversion　of　CO2.　However,　it　is　still　challenging　to　obtain　such　porous　carbons　in　a　facile　and　template-free　way.　Herein,　nitrogen-decorated　micro-mesoporous　carbons　were　synthesized　by　direct　carbonization　of　porous　organic　polymers,　which　were　developed　through　alkylation-induced　hyper-crosslink　of　rigid　organic　bases　without　the　use　of　any　templates.　The　synthesized　carbons　have　ultrahigh　surface　areas　of　2366–3580 m2/g,　total　pore　volumes　of　1.74–3.38 cm3/g　and　N　contents　of　1.50–3.24 wt%.　As　a　consequence,　the　synthesized　carbons　enable　highly　efficient　and　selective　adsorption　of　CO2　from　CO2/N2　mixed　gas,　with　the　CO2　capacities　of　1.50–2.03 mmol/g　at　0 °C　and　15 kPa,　and　IAST　selectivities　of　69–78　for　CO2/N2　(0.15/0.85　vol)　mixed　gas　at　0 °C　and　100 kPa.　After　loaded　with　metal　salts,　the　synthesized　carbons　also　exhibit　high　activities　for　the　catalytic　conversion　of　CO2,　with　the　TOFs　of　＞　600 h−1　for　cycloaddition　of　CO2　with　propylene　oxide　at　100 °C　and　1.0 MPa.　Graphical　Abstract:　[Figure　not　available:　see　fulltext.].　©　2021,　The　Author(s),　under　exclusive　licence　to　Springer　Science+Business　Media,　LLC　part　of　Springer　Nature.