Mesoporous structure of graphitic carbon nitride (g-C3N4) has been proved to be very important for artificial photosynthesis. Phosphate (PO4) group played an essential role in adenosine triphosphate (ATP) for natural photosynthesis. In this letter, mesoporous phosphorylated g-C3N4 (MPCN) was prepared from bulk g-C3N4 (BCN) by concentrated phosphoric acid post-treatment. Photocatalytic CO2 reduction results revealed that MPCN displayed a much higher activity than BCN. Brunauer-Emmett-Teller (BET) surface areas, time-resolved photoluminescence (PL) spectroscopy, photocurrent and electrochemical impedance (EIS) spectroscopy, and valence band XPS were used to explain the enhanced photocatalytic CO2 conversion performances. It was concluded that the synergistic cooperation of phosphorylation induced mesoporous structure and surface PO43- groups, and the higher photo-induced carrier separation efficiency of MPCN resulted in its enhanced photocatalytic activity for solar-to-fuels conversion over BCN. (C) 2016 Elsevier B.V. All rights reserved.