As a fast emerging topic, van der Waals (vdW) heterostructures have been proposed to modify two-dimensional layered materials with desired properties, thus greatly extending the applications of these materials. In this work, the stacking characteristics, electronic structures, band edge alignments, charge density distributions and optical properties of blue phosphorene/transition metal dichalcogenides (BlueP/TMDs) vdW heterostructures were systematically studied based on vdW corrected density functional theory. Interestingly, the valence band maximum and conduction band minimum are located in different parts of BlueP/MoSe₂, BlueP/WS₂ and BlueP/WSe₂ heterostructures. The MoSe₂, WS₂ or WSe₂ layer can be used as the electron donor and the BlueP layer can be used as the electron acceptor. We further found that the optical properties under visible-light irradiation of BlueP/TMDs vdW heterostructures are significantly improved. In particular, the predicted upper limit energy conversion efficiencies of BlueP/MoS₂ and BlueP/MoSe₂ heterostructures reach as large as 1.16% and 0.98%, respectively, suggesting their potential applications in efficient thin-film solar cells and optoelectronic devices.

Strongly suppressed recombination of electron–hole pairs, unexpectedly high carrier mobility, and anomalous optical response were found in an atomically thin indium selenide (InSe) photocatalyst. In this study, we unraveled the photocatalytic potential of two-dimensional (2D) InSe-family group-III monochalcogenide MX (M = Ga and In and X = S, Se, and Te) monolayers as water splitting hydrogen production photocatalysts on the basis of density functional theory. Our results not only highlight the high electron mobility and small exciton binding energy of 2D InSe, but also demonstrate the energy evolution of the adsorption and decomposition of water molecules as well as the hydrogen production process at the 2D InSe surface. The excellent stability of the MX monolayers was confirmed using lattice dynamical calculations as well as the ab initio molecular dynamics simulations in vacuum and aqueous environments. Moreover, distinguished optical absorption performance of the MX monolayers resulted in effective sunlight energy conversion as high as 1.20%, 6.40%, and 3.22% for the InSe, InTe, and GaTe monolayers, respectively.

Recently, flexible electrodes with biaxial/omnidirectional stretchability have attracted significant attention. However, most existing pliable electrode materials can be only stretched in one direction. In this work, an unexpected isotropic van der Waals (vdW) heterostructure is proposed, based on the assembly of two-dimensional crystals of anisotropic black phosphorene (BP) and transition metal carbide (TiC₂). Using vdW-corrected density functional theory calculations, the BP/TiC₂ vdW heterostructure was predicted to have excellent structural and mechanical stability, superior electrical conductivity, omnidirectional flexibility, and a high Li storage capacity. We have unraveled the physical origin of the excellent stability, as well as the Li adsorption preferences of the lithiated heterostructure, based on a three-step analysis of the stability of the Li-adsorption processes. In addition, the BP/TiC₂ vdW heterostructure can also be applied as the anode material for flexible Na-ion batteries because of its high Na storage capacity and strong Na binding. However, compared with Na adsorption, the capacity is higher, and the adsorption energy is more negative for Li adsorption. Our findings provide valuable insights into the exploration of a rich variety of vdW heterostructures for next-generation flexible energy storage devices.