Tailoring the Crystallographic Orientation of a Sb<sub>2</sub>S<sub>3</sub> Thin Film for Efficient Photoelectrochemical Water Reduction
Minji Yang, Zeyu Fan, Jinyan Du, Ronghua Li, Dongliang Liu, Beibei Zhang, Kuang Feng, Chao Feng, Yanbo Li
Abstract
Antimony sulfide (Sb2S3) is an emerging earth-abundant semiconductor for photoelectrochemical (PEC) water reduction. The anisotropic nature of Sb2S3 is responsible for its direction-dependent carrier transport efficiency. In general, photogenerated carriers transfer more efficiently along the [hk1] orientation than along the [hk0] orientation. However, the synthesis of a Sb2S3 film with precisely controlled [hk1] orientation is still very challenging. Herein, a completely [hk1]-oriented Sb2S3 film is prepared by sulfurizing an Ag/Sb bimetallic precursor film deposited using dual-source electron-beam evaporation. A sliver-induced crystal growth model is proposed to elucidate the formation mechanism of the [hk1]-oriented Sb2S3 film. Mechanistic studies reveal that the [hk1]-oriented Sb2S3 film has a lower defect density, a lower bulk and surface recombination, and better carrier transport efficiency in comparison to those of a randomly oriented Sb2S3 film. As a result, a photocathode based on the [hk1]-oriented Sb2S3 film delivers a high photocurrent density of 9.4 mA cm–2 at 0 V versus RHE and a high applied bias photon-to-current efficiency of 1.2% in a neutral electrolyte. Our work not only demonstrates the effectiveness of the crystal orientation of a Sb2S3 film for PEC water splitting but also provides a strategy for crystal orientation engineering of stibnite-type semiconductors for solar energy conversion applications.