Aluminum-doped cadmium sulfide homojunction photoelectrode with optimal film quality and water-splitting performance

The electronic band configuration and film quality are two crucial factors of photoelectrodes for conducting photoelectrocatalytic reactions with high efficiency and stability; thus, they need to be rationally designed. In this work, a CdS/CdS:Al-based photoanode is prepared to simultaneously enhance the optimized band structure and film quality. In this architecture, the migration of holes from the light-harvesting component (CdS) to the reduction sites (counter electrode) is inhibited, accompanied with the construction of a desirable transport path for photogenerated electrons to the reduction sites. These features consequently result in the following characteristics: rapid charge separation, a low resistance, a suppressed dark current, and an optimized onset potential. In addition, in the presence of a CdS:Al layer, the in situ grown CdS presents a reduced crystal size, enhanced hydrophilicity, and optimized film continuity. Meanwhile, density functional theory calculations (DFT) reveal that the hydrogen evolution reaction (HER) activity is enhanced after adding CdS:Al as an insertion layer. Thus, an improved MoS2/CdS:Al/CdS photoanode with high promise is achieved, demonstrating a photocurrent density in the electrolyte with a sacrificial agent of up to 7.9 mA cm(-2) (at 0 V vs. V-Ag/AgCl), an on-set potential of -1.23 V (vs. V-Ag/AgCl), good stability, and an almost totally suppressed dark current.

Automated summary

In this work, a CdS/CdS:Al-based photoanode is designed to enhance the band structure and film quality for efficient and stable photoelectrocatalytic reactions. The migration of holes from CdS to the counter electrode is inhibited, while an efficient transport path for photogenerated electrons is constructed. The addition of CdS:Al layer leads to reduced crystal size, enhanced hydrophilicity, and improved film continuity. The CdS:Al layer also enhances the hydrogen evolution reaction activity. The improved MoS2/CdS:Al/CdS photoanode exhibits high promise with a photocurrent density of 7.9 mA cm(-2) (at 0 V vs. V-Ag/AgCl), an on-set potential of -1.23 V (vs. V-Ag/AgCl), good stability, and suppressed dark current.