Synergistic enhancement of photoelectrocatalytic activity and photostability in CdS photoanodes by ultrathin polydopamine layer.

CdS-based photocatalyst and photoanode have recently drawn the attention of several investigators primarily in connection with its excellent visible light response in various catalytic reactions involving light, especially photoelectrochemical (PEC) water splitting. The present approach highlights the concept of constructing a biological functional layer incorporated for photochemical instable semiconductors for practical PEC applications. However, practical applications of CdS-based photoanodes are limited by rapid charge recombination and severe photo corrosion. This study introduces a novel approach to enhance reaction kinetics and stability. We present a CdS nanorod photoanode with an ultrathin layer of polydopamine (PDA), prepared through a conformal polymerization assembly process, which serves as a robust platform for subsequent assembly of hole cocatalysts FeOOH. The resulting sandwich structure of CdS/PDA/FeOOH photoanode demonstrates an incident to current efficiency (IPCE) of 7.1% at 420 nm and a photocurrent of 1.9 mA/cm² at 1.23 V versus the reversible hydrogen potential (RHE). The integrated photoanode exhibits significantly prolonged photostability compared to CdS, CdS/PDA, and CdS/FeOOH photoanodes. The significance of this work lies in constructing a FeOOH structure (with hole extraction and consumption capabilities) on the CdS outermost layer using an easy-to-operate preparation process, thereby revealing the ability of PDA to enable the passage of photogenerated holes. The present approach highlights the concept of integrating biologically functional layers to stabilize photochemically unstable semiconductors for practical PEC applications. [ABSTRACT FROM AUTHOR]