Facile approaching hierarchical CdS films as electrode toward photoelectrochemical water splitting

The facile generation of hierarchical CdS films and their accompanying application comparison as efficient photocatalytic electrodes toward water splitting were successfully achieved in this study. Three hierarchical CdS films, including nanoparticle packing film (CdS_P), neat film (CdS_N) and homojunction film (CdS_H) deposited on an indium tin oxide (ITO) substrate, were realized by virtue of chemical bath deposition (CBD), atomic layer deposition (ALD) and the well-programmed combinational deposition (PCD) protocol with the above two processes successively. The experimental details demonstrate that the CdS_H film acquired from PCD affords an amazing photocatalytic boost toward water splitting, which may profit from the larger surface area and from better absorption. The adoption of CdS_H film as a photocatalyst can result in up to 22.18 times or 3.34 times the enhancement of the photocurrent density compared to reference devices with a CdS_P or CdS_N photoelectrode, indicating the effectiveness of the excogitation of the programmed protocol. Ultraviolet photoelectron spectroscopy was utilized to elucidate the electronic structures of the CdS_H bilayer photoanode, and the dependence of their directional photocurrent on the energy level alignment was also depicted. This work not only excogitates the programmed deposition protocol that may be facilely extended to the fabrication of other hierarchical nanomaterials but also gives prominence to the importance of morphology and interfacial energetic control toward enhancing catalytic efficiency. (paper)