X-Shaped α-FeOOH with Enhanced Charge Separation for Visible-Light-Driven Photocatalytic Overall Water Splitting

Photocatalytic overall water splitting (POWS) is a promising route for converting solar energy into green and sustainable energy. Herein, we report a facile hydrothermal approach for the fabrication of x-shaped α-FeOOH photocatalysts containing high-index facets for POWS. The x-shaped α-FeOOH photocatalysts exhibited enhanced visible-light-driven POWS activities in comparison with that of FeOOH without x-structures, with a maximum H₂ and O₂ evolution rate of 9.2 and 4.7 μmol h^-1  g^-1 , respectively. The morphology and particle size of the α-FeOOH could be controlled by adjusting the NH₄ F concentration in the precursors. The photodeposition of Pt and RuO₂ on the x-shaped α-FeOOH revealed the specially separated reduction and oxidation centers on the surface of α-FeOOH, with the oxidation-active sites selectively located on the edges of the α-FeOOH x-structures. Electrochemical experiments further affirmed the enhanced charge separation in the x-shaped α-FeOOH. The smaller particle size and unique x-shape of the α-FeOOH photocatalyst were shown to enhance the POWS performance owing to the large specific surface area, high proportion of exposed high-index facets, high electron-transfer efficiency and effective separation of the photogenerated electron-hole pairs. The current study revealed that the x-shaped α-FeOOH products could serve as cost-effective and stable photocatalysts for POWS.