The invention discloses a method for preparing a
cobalt carbonate-
cobalt phosphate composite photocatalyst. The method comprises the following specific steps: weighing 12mmol to 16mmol of
cobalt nitrate, preparing a 12mmol / L cobalt
nitrate solution, weighing 6.6mmol to 8mmol of
sodium carbonate, and preparing a 16mmol / L
sodium carbonate solution; mixing the two kinds of solutions at the revolution rate of 350rpm to 400rpm so as to form a colloidal substance, carrying out sustained stirring for 3 to 4 hours, and subjecting
sodium carbonate and cobalt
nitrate to a reaction during stirring, so as to produce cobalt carbonate
colloid; putting the cobalt carbonate
colloid in a semi-permeable membrane bag, washing with
distilled water for 3 to 4 times so as to remove free ions, then, adding the cobalt carbonate
colloid into 60mL to 80mL of 2mol / L to 4mol / L sodium
phosphate solution, carrying out soaking for 2 to 4 days so as to form
cobalt phosphate nanoparticles on surfaces of cobalt carbonate particles, carrying out
solid-liquid separation, washing solids with deionized water for 2 to 3 times, and carrying out
drying at the temperature of 75 DEG C to 105 DEG C, thereby preparing the cobalt carbonate-
cobalt phosphate composite photocatalyst. According to the method, a catalyst is formed on the surface of cobalt carbonate, and the catalyst and a support are combined tightly.