The invention discloses a modified 
ferrihydrite / 
hematite nano-rod core-shell structure compound light 
anode and an application thereof. A preparation method of the light 
anode includes the steps: S1 preparing 
hematite growth solution, placing a conducting substrate into the 
hematite growth solution, synthesizing a FeOOH film on the conducting substrate by a 
solvent thermal synthesis method, washing the FeOOH film, and 
drying the washed FeOOH film for standby application; S2 performing high temperature annealing on the conducting substrate acquired in the step S1, and cooling the conducting substrate to obtain the conducting substrate with the hematite film surface; S3 preparing 
ferrihydrite growth solution, placing the conducting substrate acquired in the step S2 into the 
ferrihydrite growth solution, heating mixture, washing the conducting substrate after reaction is completed, and 
drying the washed conducting substrate to obtain the modified ferrihydrite / hematite nano-rod core-shellstructure compound light 
anode. According to the method, a ferrihydrite 
thin layer is loaded on the surface of the hematite to prepare the core-shell structure compound light anode which is resistantto light 
corrosion and good in photoelectrochemical property and stability, and the compound light anode can be used for decomposing water to generate 
hydrogen and is high in 
catalytic efficiency andstable in 
catalytic effect.