Tailoring ZnO–CdO Nanocomposite Photoanodes Mimicking Neural Web Like Structure for Optimized Solar Water Splitting

The efficient photoelectrochemical (PEC) water splitting requires semiconductor photocatalyst with high light absorption, favorable band position, minimum electron-hole recombination, and high stability. Zinc oxide–cadmium oxide (ZnO–CdO) nanocomposites are among those candidates for PEC water splitting, offering the potential to harness solar energy for sustainable hydrogen generation. Here, this study first time reports the use of ZnO–CdO nanocomposites prepared using simple, robust, and affordable successive ionic layer adsorption and reaction method for PEC water splitting. The X-ray diffraction reveals the coexistence of ZnO and CdO crystallites with an average size of ≈10 nm, microstrain ≈14.4 × 10⁻³, and dislocation density ≈15.0 × 10¹⁵ m⁻². The optical studies show increased absorption for the nanocomposite as compared to bare ZnO sample. The morphological studies reveal that the neural web-like structure with increased surface area effectively improves light harvesting through developing a light trap and significantly accelerates carrier kinetics processes because of its larger interface contacting zones with the electrolyte, which further provides direct paths for rapid carrier separation and transfer. The PEC studies shown a faster photo response and lower charge transfer impedance which resulted in better photoconversion efficiency and optimum photocurrent density of 0.52 mA cm⁻², a 10-fold that of bare ZnO and four-fold of bare CdO.