CdS/ZnFe₂O₄ Core–Shell Nanorod Arrays on Modified TiO₂ Photoanodes for Photoelectrochemical Water Splitting

The photoelectrochemical (PEC) photoanode is highly expected to address the energy crisis and environmental pollution in the future. Herein, a ternary heterojunction photoanode with well-designed morphology and stair-like band alignment has been successfully fabricated by growing CdS/ZnFe 2 O 4 core–shell nanorod arrays (NRAs) on the tops of TiO 2 NRAs (TiO 2 /CdS/ZnFe 2 O 4 ). The light harvesting ability and PEC performance of the TiO 2 /CdS/ZnFe 2 O 4 NRAs photoanode are significantly augmented, as optimized TiO 2 /CdS/ZnFe 2 O 4 yields a remarkable photocurrent density of 4.75 mA/cm 2 and a significant applied bias photon-to-current efficiency of 3.00%, which are 8.6 and 9.1 times those of the unmodified TiO 2 NRAs photoanode, respectively. The substantially boosted PEC performance is attributed to efficient charge transfer and separation achieved by the staircase-like band structure between TiO 2, CdS, and ZnFe 2 O 4 . This excellent scheme provides an avenue to construct an efficient TiO 2 -based photoanode with special morphology and stair-like band alignment for the PEC water splitting field.