Carbon-nitrogen-coated transition metal cluster photocatalyst as well as preparation method and application thereof

The invention relates to the field of photocatalysts, and discloses a carbon-nitrogen coated transition metal cluster photocatalyst as well as a preparation method and application thereof. The method comprises the following steps: in the presence of an organic solvent, mixing transition metal nitrate with diaminomaleonitrile, and then carrying out hydrothermal reaction on the mixture to obtain a solid-phase product; the transition metal nitrate is selected from at least one of cobalt nitrate, ferric nitrate and copper nitrate; the molar ratio of the transition metal nitrate to the diaminomaleonitrile is 1: (1-3); the hydrothermal reaction conditions are as follows: the temperature is 120-140 DEG C, and the time is 8-15 hours; roasting the solid-phase product under the protection of inert gas, and then pickling the roasted product; the roasting conditions are as follows: the heating rate is 3-10 DEG C/min, the temperature is 450-700 DEG C, and the time is 1-4 hours. The photocatalyst obtained by the method can