Preparation method and applications of nano-scale magnetic cobalt-manganese spinel

The invention provides a nano-scale magnetic cobalt-manganese spinel preparation method, which comprises: dissolving a cobalt source and a manganese source in a mixed solution containing ammonia waterand ammonium chloride, adding sodium hypochlorite as an oxidizing agent, oxidizing part of the divalent manganese into trivalent manganese to form a divalent and trivalent manganese ion coexisting homogeneous system, carrying out a reaction at 120-180 DEG C for more than 2 h by using urea as a precipitator to crystallize so as to form a precursor, and calcining the precursor sample at 400-600 DEGC for more than 2 h to obtain the nano-scale magnetic cobalt-manganese spinel. According to the invention, the prepared nano-scale magnetic cobalt-manganese spinel crystal form is high in integrity degree and uniform in particle, has a particle size of about 50 nm, has strong magnetism, and is easy to separate under the condition of an external magnetic field; and the nano-scale magnetic cobalt-manganese spinel can be use