摘要： Graphite carbon nitride (g-C3N4) is a promising candidate as an efficient, affordable, and sustainable alternative photocatalyst owing to its unique physical and chemical properties. However, the photocatalytic activity of pristine g-C3N4 is still far below what is expected, because of its insufficient active site and high electron-hole recombination rates. Herein, we develop a novel strategy ― a one-step hydroxy-carbonate-assisted route ― to try to overcome these disadvantages in g-C3N4 nanosheets by creating substantial pores ranging from mesoporous to macropore, which are mainly caused by the partial breaking of hydrogen bonds and removing of magnesium oxide. Luxuriant pores in g-C3N4 not only serve as a reaction center by providing a large number of active sites at pore edges, but also effectively improve the photogenerated carrier separation by shortening their transfer lengths. The highly efficient visible-light photocatalytic activity of porous g-C3N4 nanosheets are demonstrated by degrading methyl blue (MB) and gentian violet (GV) as models, which its degradation rate constant is respectively more than 109 times and 12 times higher than those of pristine g-C3N4. Meanwhile, the high porous g-C3N4 has robust stability. The simple and effective strategy proposed here provides a direct route to highly functionalized g-C3N4 nanosheets and other layered semiconductors for various applications.