Doping engineering achieves BiVO4 and hematite band matching accelerating photoelectrochemical water splitting

[Display omitted] •A simple solvothermal method was developed to load Mn-doped hematite on BiVO4 surface and improve its PEC performance.•The doping of Mn can regular electronic structure of Fe sites and enhance OER activity.•Mn-doped hematite can efficiently collect and store photogenerated holes.•Mn element doping decrease the fermi lever of hematite so that it forms a type Ⅱ heterojunction with BiVO4 and accelerating bulk charge migration. Poor charge transfer ability and slow surface water oxidation kinetics have severely limited the efficiency of BiVO4 photoanodes. The construction of heterojunctions and supported cocatalysts are two well-established solutions, the former can improve charge transfer position, and the latter can effectively accelerate water oxidation. Herein, we adopted a simple solvothermal method to grow Mn-doped hematite directly on the BiVO4 surface, which acts as both a heterojunction and a cocatalyst. The synthesized photoanodes exhibits a significant increase in photocurrent density, from 1.42 to 3.42 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE). On the one hand, the doped samples exhibited better OER activity, and on the other hand, the Mn-doped hematite had a band structure that was more compatible with BiVO4. Both effects make the synthesized photoanode have good PEC performance. Our research provides a new approach for the design of PEC photoanodes and contributes to understand the charge behavior of heterojunction co-catalysis.