Fully blossomed WO₃/BiVO₄ structure obtained via active facet engineering of patterned FTO for highly efficient Water splitting

Materials with anisotropic properties have different electronic structures and photoelectrochemical (PEC) performance depending on the facet. Herein, we controlled the morphology of WO₃ nanoflakes, and the ratio of the revealed WO₃ facet using patterned F-doped SnO₂ fabrication by means of direct printing. In the case of WO₃ NF synthesized on patterned FTO (FB-WO₃/BiVO₄), the proportion of the (002) facet decreased and that of the (200) and (020) facets increased in comparison to the case when NF were synthesized on flat FTO (B-WO₃/BiVO₄). As the facet ratio changed, the band structure and efficiency changed. The photocurrent density of FB-WO₃/BiVO₄ was 1.50 mA/cm², which was 34% higher than that of B-WO₃/BiVO₄ (1.12 mA/cm²) at 1.23 V_RHE. Our results indicate that the efficiency of PEC water splitting can be increased by engineering the exposed facet according to the shape of the substrate, rather than varying the synthetic method.