Seed layer-assisted growth of branched Bi2S3 nanostructure on α-Fe2O3 thin film for improved photoelectrochemical performance

Incorporating a narrow bandgap semiconductor to α-Fe2O3 with matched energy positions is a promising route for improving the light-harvesting ability and charge transporting efficiency for photoelectrochemical (PEC) water splitting. Herein, the preparation of heterojunction with uniform Bi2S3 nanobranches grown on the α-Fe2O3 nanorod film was reported through a seed layer-assisted growth mechanism. By controlling successive numbers of Bi2S3 seed layers before the subsequent Bi2S3 solvothermal reaction, rod-like Bi2S3 nanobranches were well assembled on α-Fe2O3 nanorod film. PEC investigation results revealed that the as-prepared α-Fe2O3/Bi2S3 heterojunction exhibited the highest photocurrent density of 11.55 mA/cm2 at 0.9 V vs. RHE, which was 14.43 and 5.2 times higher than that of pristine α-Fe2O3 and α-Fe2O3/Bi2S3 samples prepared without a Bi2S3 seed layer, respectively. The dramatic enhanced PEC performance was attributed to improved light-harvesting efficiency and more efficient photogenerated electron–hole separation in the composite. These results demonstrated that the assembly of branched Bi2S3 nanostructures on α-Fe2O3 films should be a promising photoanode for PEC applications.