Performance enhancement of α-Fe2O3@Bi2S3 heterojunction for photocathodic protection of 304SS

Hematite (α-Fe 2 O 3 ) is one of the most promising candidates as a photoanode for photocathodic protection (PCP) of 304SS. However, serious charge recombination has hindered the application. In this work, we verified the feasibility of constructing heterojunction for enhancing the PCP performance. α-Fe 2 O 3 @Bi 2 S 3 can not only broaden the solar light absorption region but also provide a built-in electric field to improve charge separation and close junctions for charge transport. When α-Fe 2 O 3 @Bi 2 S 3 was coupled with 304SS, the OCP under illumination negatively shifted to −0.788 V Ag/AgCl , which was ca . 600 mV negative than the corrosion potential of 304SS. The photoinduced current density reached 32 μA cm −2 , outperforming the bare Bi 2 S 3 and α-Fe 2 O 3 . The formation of a type II heterojunction between Bi 2 S 3 and α-Fe 2 O 3 was proposed and verified by the electrochemical impedance measurements.