Coral-like Sb2Se3/SnS2 photocathode co-optimized by bilayer Sb2Se3 structure and hole-storage layer for photoelectrochemical water splitting

Abstract

Achieving high light absorption efficiency and low photogenerated carrier recombination rates is critical in the production of H 2 by photoelectrochemical water splitting. Antimony selenide (Sb 2 Se 3 ) has recently received much attention due to its favorable optoelectronic properties, low cost and unique nanorod structure. Herein, we constructed coral-like Sb 2 Se 3 /SnS 2 heterojunction by introducing SnS 2 with a nanosheet structure, which contributes to enhanced light absorption and provides more reaction sites. On this basis, synergistic optimization is carried out by the bilayer Sb 2 Se 3 structure and ferrihydrite (Fh) to effectively inhibit charge recombination at the interface and facilitate electron transport. Compared to monolayer Sb 2 Se 3 (1.54%), the IPCE value of bilayer Sb 2 Se 3 /SnS 2 /Fh can reach 20.56% (735 nm). The prepared bilayer Sb 2 Se 3 /SnS 2 /Fh has a maximum photocurrent density of approximately − 1.0 mA cm −2 at 0 V RHE , continuous testing for 1 h compared to monolayer Sb 2 Se 3 still maintains more than 4 times improvement. This work provides a basis for the development of high efficiency and low cost Sb 2 Se 3 -based optoelectronic devices. • The bilayer Sb 2 Se 3 structure was constructed by sequential deposition. • A combination between 1D Sb 2 Se 3 nanorods and 2D SnS 2 nanosheets has been achieved. • Surface modification using ferrihydrite as an interface engineering material. • Optimized photoelectrode current density is 50 times higher than original sample. • The PEC mechanism of bilayer Sb 2 Se 3 /SnS 2 /Fh photoelectrode was proposed.