▎ 摘　　要

We report on a (Mn2+-Fe2O3)/reduced graphene oxide/(Fe3+-WO3) heteronanostructure (HNS) as a building block for photoelectrochemical (PEC) anodes: an array of Fe3+-doped WO3 nanorods (NRs) was covered with reduced graphene oxide (RGO), and both the NRs and RGO were decorated with Mn2+-doped alpha-Fe2O3 nanoparticles (NPs). Efficient electron-hole separation and carrier migration are ascribed to midgap states (MGSs) obtained via doping, type-II band alignment of WO3 and alpha-Fe2O3, and highly conductive RGO. In particular, the PEC efficiency enhances at first and then decays with increasing Mn2+ doping concentration. The optimum Mn2+ concentrations of 1% via experiment and 2% through density functional theory (DFT) are confirmed. DFT calculations reveal that the band structure of alpha-Fe2O3 can be modulated via tuning the Mn2+ concentration. With increasing Mn2+ concentration, the bandgap gradually narrows, and the MGSs gradually approach then merge into the valence band (VB) due to hybridization interactions between Mn2+, O2-, and Fe3+ ions. Overall, we anticipate that this kind of HNS with modulated band structure can supply inspiration to the design and development of semiconductor materials for photoconversion applications.