Antimony selenide (Sb ₂ Se ₃), a quasi‐1D material with anisotropic photovoltaic properties, is a promising absorber for photoelectrochemical (PEC) water splitting. This work demonstrates a crystal engineering strategy for hydrothermal deposition of preferentially hk1‐oriented Sb ₂ Se ₃ films with enhanced crystal quality. Introducing Ag ^+ into precursor solutions fundamentally alters nucleation kinetics by mediating MoO ₗ formation at the Mo substrate interface. This interfacial modification reduces the heterogeneous nucleation barrier and promotes anisotropic hk1 growth. The resulting Sb ₂ Se ₃ photocathode achieves a photocurrent density of 24. 7 mA cm ^−2 at 0 V ₑ₇₄ in 1 m H ₂ SO ₄ and an applied bias photon‐to‐current efficiency (ABPE) of 2. 5% compared with pristine counterparts (14. 9 mA cm ^−2 at 0 V ₑ₇₄, ABPE of 1. 1%) with superior operational stability. The PEC performance enhancement originates not only from preferential crystal orientation optimizing charge transport, but also from suppressed non‐radiative recombination. This study establishes an effective hydrothermal approach for fabricating high‐performance hk1‐oriented Sb ₂ Se ₃ photoelectrodes by ion‐modulated crystal growth.
Zhang et al. (Sat,) studied this question.