Fabrication of a preferentially [001]-oriented Sb2Se3 thin film on diverse substrates and its application in photoelectrochemical water reduction

Abstract

Layered Sb₂Se₃ consists of infinite chains of repeating Sb₄Se₆ units stacked along the c-axis via Sb–Se covalent bonds, whereas they are linked by van der Waals force along the a-axis and b-axis. It usually tends to grow along the [hk0] orientation with low surface energy. However, [001]-oriented growth, which efficiently enhances charge transport, is often considered unstable due to its high surface energy. Herein, we propose a growth method to fabricate Sb₂Se₃ thin films with the preferential [001]-orientation on various substrates (Mo, MoSe₂, SLG, NiO, SiO₂ and FTO). This crystal facet design of preferentially [001]-oriented Sb₂Se₃ exposes the majority of the nanoribbons vertically aligned to the substrate, and thus maximally improves the charge transport, which may find applications in diverse optoelectronic devices. We confirmed their performance in photoelectrochemical water reduction. The preferentially [001]-oriented Sb₂Se₃ photocathode exhibited an impressive photocurrent density of −20.5 mA cm⁻² at 0 V vs. RHE and a maximum photocurrent density of −28 mA cm⁻² at −0.2 V vs. RHE under 1 sun AM 1.5 G illumination. Thus, the successful use of this [001]-Sb₂Se₃ photocathode paves the way for the development of high-efficiency Sb₂Se₃-based devices for optoelectronic applications.