In this study, we implemented a densely packed subwavelength-scale nanocone array, inspired by the morphology of motheye, using a direct printing method. Then, we fabricated triple-deck hierarchical photoanodes on motheye templates through successive deposition of Au, SnO2, and BiVO4 layers. The fabricated motheye structure exhibits a gradual refractive index change, which is excellent for lowering the reflection of high refractive index materials. Also, the synergy between the light trapping effects of the nanocone array and the gap-plasmon structure (reflector/spacer/antenna) maximized the absorption of incident solar light. Due to this enhancement, a current density of 1.481 mA/cm2 was obtained with a thin layer of BiVO4 (200 nm), which is 3.39 times higher than that obtained from a non-patterned structure (reference). Our results could be used for many promising candidate materials for photoanode and optoelectronic devices.
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