A uniformly decorated and photostable polydopamine–organic semiconductor to boost the photoelectrochemical water splitting performance of CdS photoanodes

Abstract

Photoelectrochemical (PEC) water splitting to produce renewable H₂ fuel by storage of solar energy has attracted increasing attention as it could reduce carbon footprint and solve the global consumption growth. Herein, a photostable polymer polydopamine (PDA) was introduced to enhance the PEC performance by forming a uniform inorganic–organic hybrid heterostructure with CdS. The organic semiconductor PDA not only forms a strong coordinate bond to facilitate the transfer of electrons, but also acts as a passivation layer, contributing to improve the stability of the photoelectrode. A photocurrent density of 1.08 mA cm⁻² was achieved for CdS/1PDA, which was about 2.4 times that of bare CdS at 0.28 V vs. RHE, and CdS/1PDA featured a reasonable photocurrent stability compared with bare CdS. The Co–Pi co-catalyst, as a hole acceptor, further prohibited charge recombination and promoted the water oxidation kinetics. The photocurrent density of CdS/1PDA/5Co–Pi was up to 2.68 mA cm⁻² (0.28 V vs. RHE), which was 5.7 and 2.5 times higher than that of bare CdS and CdS/1PD, respectively. The strategy provides a beneficial insight to design an inorganic–organic uniform heterostructure for the enhancement in PEC performance.