Dissolve an appropriate amount of NH4VO3 in a certain amount of deionized water and heat until completely dissolved. According to the amount of substance n(Fe)/n(V)=1, dissolve an appropriate amount of Fe(NO3)3·9H2O in a certain amount of deionized Water, configured as a solution of a certain concentration. Under magnetic stirring, the iron salt solution was slowly added to the NH4VO3 solution and stirred for 30 minutes to obtain a precursor solution. It was transferred to a three-necked flask, placed in a microwave reactor, and reacted at 100 ° C for 6 min at a constant power. After the reaction was stopped, it was naturally cooled, centrifuged, washed alternately with distilled water and ethanol three times, and dried in a drying oven at 80 ° C to obtain a FeVO4 precursor. A certain amount of Cu(NO3)2·3H2O is weighed according to n(Cu)/n(V)=3:2, and the Cu3(VO4)2 precursor can be obtained by the same preparation procedure as FeVO4.