Heat-assisted preparation method and application of graphite-phase carbon nitride nanosheet

The invention discloses a heat-assisted preparation method of g-C3N4 nanosheets, which specifically comprises the following steps: putting melamine into an alumina crucible with a cover, heating in a muffle furnace to obtain bulk-phase graphite-phase carbon nitride, carrying out secondary calcination to obtain graphite-phase carbon nitride nanosheets, weighing graphite-phase carbon nitride nanosheet powder, dispersing the graphite-phase carbon nitride nanosheet powder into ethanol, and carrying out ultrasonic treatment, to obtain graphite-phase carbon nitride nano ultrasonic suspension liquid; then, dripping H2PtCl6 into the graphite phase carbon nitride nano ultrasonic suspension liquid, and drying the mixture overnight; and finally, heating by adopting a tubular furnace in an H2/Ar atmosphere, thereby obtaining the product. According to the preparation method disclosed by the invention, the Pt/g-C3N4 nano-composite photocatalyst is prepared by adopting a high-temperature auxiliary thermal stripping and hydr