Two-Dimensional Direct <i>Z</i>-Scheme LiInP₂S₆/XTe₂ (X = Mo and W) Heterostructures for Photocatalysis

Recently, two-dimensional (2D) layered metal–phosphorus trithionite (LiInP2S6) has been synthesized and has exhibited outstanding ferroelectricity and photoelectronic properties. However, the indirect band gap of the LiInP2S6 monolayer significantly restricts its applicability in optoelectronic devices. Therefore, in this work, we systematically researched the optoelectronic properties of two LiInP2S6/XTe2 (X = Mo and W) van der Waals heterojunctions (vdWHs) using first-principles calculations. Our results demonstrate that both vdWHs undergo an indirect-to-direct band gap transition and display strong optical absorption across the visible spectrum, markedly improving absorption efficiency. Moreover, these two vdWHs exhibit the most remarkable electron mobility as high as 4.21 × 103 cm2 V–1 s–1. Notably, an intrinsic built-in electric field is established at the interface of the LiInP2S6/XTe2 heterojunction, facilitating the formation of a potential Z-scheme of charge transfer modes therein. Importantly, the energy band edges of these vdWHs precisely span the redox potential of water, thereby confirming LiInP2S6/MoTe2 and LiInP2S6/WTe2 as promising platforms for high-performance photocatalytic applications.