We fabricated Mo:BiVO4/Co:BiVO4 photoanodes by depositing Co:BiVO4 layers on top of Mo:BiVO4 layers, and demonstrated the enhanced PEC performances with improved charge separation both in the bulk and at the interface by doping strategy in this work. Co:BiVO4 layers in Mo:BiVO4/Co:BiVO4 photoanodes were found to be important for the enhanced charge separation efficiencies. The surface exposed Coe' ions in Co:BiVO4 layers can act as reactive sites for water oxidation to promote the interfacial charge separation. While, the Coe' doping inside Co:BiVO4 cannot only tune the built in electric fields in Mo:BiVO4/Co:BiVO4 homojunctions, but also be able to optimize the charge transport in Co:BiVO4 layers to facilitate the bulk charge separation. By optimizing the Co contents and the number of Co:BiVO4 layers in Mo:BiVO4/Co:BiVO4 photoanodes, 3Mo-lCo-6% consisted of 3 layers of 3% Mo:BiVO4 and 1 layer 6% Co:BiVO4 yields the highest photocurrent of 2.09 mA/cm2 at 1.23 V vs RHE, with a eta(b) and eta(i), value of 77.8% and 86.5%, respectively. This work provides a new thread for the design and fabrication of photoanode with high charge separation efficiencies by doping strategy, which could be helpful for the further improvement of PEC water splitting performances. (C) 2017 Published by Elsevier B.V.