CdS/ZnFe₂O₄ Core–ShellNanorod Arrays on Modified TiO₂ Photoanodes for PhotoelectrochemicalWater Splitting

Abstract

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/ZnFe₂O₄ core–shell nanorod arrays (NRAs) on the tops of TiO₂ NRAs (TiO₂/CdS/ZnFe₂O₄). The light harvesting ability and PEC performance of the TiO₂/CdS/ZnFe₂O₄ NRAs photoanode are significantly augmented, as optimized TiO₂/CdS/ZnFe₂O₄ yields a remarkable photocurrent density of 4.75 mA/cm² and a significant applied bias photon-to-current efficiency of 3.00%, which are 8.6 and 9.1 times those of the unmodified TiO₂ NRAs photoanode, respectively. The substantially boosted PEC performance is attributed to efficient charge transfer and separation achieved by the staircase-like band structure between TiO₂, CdS, and ZnFe₂O₄. This excellent scheme provides an avenue to construct an efficient TiO₂-based photoanode with special morphology and stair-like band alignment for the PEC water splitting field.