No abstract

No abstract

Using first-principles calculations, we show that a two-dimensional van der Waals (vdW) InSe/GaTe heterobilayer (HBL) can serve as a potential visible-light-driven photocatalyst for water splitting to produce hydrogen, which notably improves the photocatalytic performance over that of isolated InSe and GaTe monolayers. The type-II band alignment and high carrier mobility of the InSe/GaTe HBL facilitate the spatial separation of photogenerated carriers and thus enhance the photocatalytic efficiency. Meanwhile, the separate absorption of H+ and OH– on the surfaces of InSe/GaTe HBL is beneficial to the photocatalytic redox reactions. Moreover, InSe/GaTe HBL can significantly extend the range of light harvesting from visible light to infrared light. The predicted maximum power conversion efficiency achieved is 12.3%. These results indicate the InSe/GaTe HBL is a promising photocatalyst for water splitting.

Sliding ferroelectricity (SFE) found in two-dimensional (2D) van der Waals (vdW) materials, such as BN and transition-metal dichalcogenides bilayers, opens an avenue for 2D ferroelectric materials. Multiferroic coupling in 2D SFE materials brings us an alternative concept for spintronic memory devices. In this study, using first-principles calculations, we demonstrate that MnSe multilayers constructed by the recently-synthesized MnSe monolayer have large sliding-driven reversible out-of-plane electric polarization (~10.6 pC m−1) and moderate interlayer sliding barriers superior to the existing 2D SFE materials. Interestingly, the intrinsic electric polarization is accompanied by nonzero net magnetic moments which are also switchable via lateral interlayer sliding. Additionally, both SFE and magnetoelectric coupling can be effectively regulated by external strain and/or hole doping. Our findings suggest the potential of MnSe multilayers in 2D multiferroic and spintronic applications.

The two-dimensional (2D) hybrid structures of boron nitride (BN) and graphene with properties superior to the individuals are long desired. In this work, we demonstrate theoretically that this goal can be reached in a new graphene-like borocarbonitride (g-BC6N) whose domain has been synthesized in recent experiments. It has a direct band gap of 1.833 eV and a high carrier mobility comparable to that of black phosphorene. The inversion symmetry breaking in g-BC6N leads to a pair of inequivalent valleys with opposite Berry curvatures in the vicinities of the vertices (K and K') of the Brillouin zone. The coexistence of valley-selective circular dichroism and high carrier mobility in g-BNC6 is beneficial to realize the valley Hall effect. We also propose a tight-binding (TB) model to describe the intrinsic features of this type of lattice, revealing a new class of 2D valleytronic materials.