Epitaxial Grown Sb2Se3@Sb2S3 Core–Shell Nanorod Radial–Axial Hierarchical Heterostructure with Enhanced Photoelectrochemical Water Splitting Performance

Antimony selenide (Sb₂Se₃) as a light-harvesting material has gradually attracted the attention of researchers in the field of photoelectrocatalysis. Uniquely, the crystal structure consists of one-dimensional (Sb₄Se₆)_n ribbons, with an efficient carrier transport along the ribbon [001] direction. Herein, a novel Sb₂Se₃@Sb₂S₃ core-shell nanorod radial-axial hierarchical heterostructure was successfully fabricated by epitaxial growth strategy. Taking advantage of the isomorphous and anisotropic binding modes of (Sb₄S(e)₆)_n ribbons for Sb₂Se₃ and Sb₂S₃, the epitaxially grown core-shell heterostructure forms a van der Waals heterojunction across the radial direction and covalently bonded heterojunction along the axial direction. A photocurrent of 1.37 mA cm^-2 was achieved at 0 V vs RHE for the hierarchical Sb₂Se₃@Sb₂S₃ nanorod photoelectrode with [101] preferred orientation, up to 40 times higher than for pure Sb₂Se₃. Moreover, the FeOOH was introduced as a cocatalyst. The photoelectrode decorated with FeOOH shows better stability with a H₂ generation rate of 18.9 μmol cm^-2 h^-1 under neutral conditions. This study provides a new insight into the design of antimony chalcogenide heterostructure photoelectrodes for photoelectrochemical water splitting.