Preparation method of cobweb-shaped ultrathin C3N5 nanosheet

The invention provides a preparation method of a cobweb-shaped ultrathin C3N5 nanosheet. The preparation method comprises the following steps: firstly, calcining melamine, refluxing, adding a hydrazine hydrate solution, carrying out hydrothermal reaction, removing impurities from a hydrothermal product, and drying; and finally, grinding and uniformly mixing the product with a certain amount of sodium bicarbonate, sodium hydroxide and sodium chloride according to a certain ratio, calcining, washing the product for multiple times, and drying to obtain the cobweb-shaped ultrathin C3N5 nanosheet. The mixture of sodium bicarbonate, sodium hydroxide and sodium chloride is used as a pore-forming agent and a structure-directing agent, so that the prepared C3N5 has a large number of hierarchical porous structures; the light absorption can be improved, the mass transfer rate can be effectively improved, the active sites of the reaction can be increased, the specific surface area can be increased, the migration distance