Integrated Heterostructure of PDA/Bi-AgIn5S8/TiO2 for Photoelectrochemical Hydrogen Production: Understanding the Synergistic Effect of Multilayer Structure

Overcoming one of most challenging limitations of bare TiO 2 with large bandgap can be achieved by rational design and fabrication of heterostructures. Multicomponent sulfides with a nature of tunable band structure can be a good alternative to decorating TiO 2 , but there remains a major trade-off between the high efficiency and the long-term durability, so the stability issue must be addressed upon the use of sulfides. Here, an effective strategy is demonstrated with Bi-doped AgIn 5 S 8 (Bi-AgIn 5 S 8 ) decorated TiO 2 photoanode, where twofold enhancement of the photocurrent is achieved. More importantly, it is the first time to integrate polydopamine passivation layer and AgIn 5 S 8 for simultaneously enhancing the solar conversion efficiency and stability. The incident photon-to-current conversion efficiency value is tuned up to 45% (0.4 V vs Ag/AgCl), and the photocurrent density can keep for 90.8% after 5 h. Corresponding hydrogen evolution rate has increased to 8.6 µmol h −1 , which is three times higher than that of bare TiO 2 .