Epitaxial Grown Sb 2 Se 3 @Sb 2 S 3 Core-Shell Nanorod Radial-Axial Hierarchical Heterostructure with Enhanced Photoelectrochemical Water Splitting Performance.

Antimony selenide (Sb 2 Se 3 ) 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 (Sb 4 Se 6 ) n ribbons, with an efficient carrier transport along the ribbon [001] direction. Herein, a novel Sb 2 Se 3 @Sb 2 S 3 core-shell nanorod radial-axial hierarchical heterostructure was successfully fabricated by epitaxial growth strategy. Taking advantage of the isomorphous and anisotropic binding modes of (Sb 4 S(e) 6 ) n ribbons for Sb 2 Se 3 and Sb 2 S 3 , 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 Sb 2 Se 3 @Sb 2 S 3 nanorod photoelectrode with [101] preferred orientation, up to 40 times higher than for pure Sb 2 Se 3 . Moreover, the FeOOH was introduced as a cocatalyst. The photoelectrode decorated with FeOOH shows better stability with a H 2 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.