A facile one-step approach was employed to synthesize porous g-C3N4 flake (PCNF) via thermally polymerizing melamine with the presence of MgCO3 template. CO2 gas released from the decomposition of MgCO3 prohibited the further polymerization of CN framework and separated the CN layers to produce a flake-like morphology, and meanwhile the removal of MgO nanoparticles resulted in a porous structure. The resultant PCNF exhibited enhanced visible-light photocatalytic activity for degrading organic dyes, and its rate constant is 4 times higher than that of bulky CN. What is more, this material presented an excellent stability and superior universality for various pollutants. (C) 2017 Elsevier Ltd. All rights reserved.