Blue phosphorene (BlueP) is a graphene-like phosphorus nanosheet which was synthesized very recently for the first time [Nano Lett., 2016, 16, 4903–4908]. The combination of electronic properties of two different two-dimensional materials in an ultrathin van der Waals (vdW) vertical heterostructure has been proved to be an effective approach to the design of novel electronic and optoelectronic devices. Therefore, we used density functional theory to investigate the structural and electronic properties of two BlueP-based heterostructures – BlueP/graphene (BlueP/G) and BlueP/graphene-like gallium nitride (BlueP/g-GaN). Our results showed that the semiconducting nature of BlueP and the Dirac cone of G are well preserved in the BlueP/G vdW heterostructure. Moreover, by applying a perpendicular electric field, it is possible to tune the position of the Dirac cone of G with respect to the band edge of BlueP, resulting in the ability to control the Schottky barrier height. For the BlueP/g-GaN vdW heterostructure, BlueP forms an interface with g-GaN with a type-II band alignment, which is a promising feature for unipolar electronic device applications. Furthermore, we discovered that both G and g-GaN can be used as an active layer for BlueP to facilitate charge injection and enhance the device performance.

Using first-principles calculations, we systematically investigated the electronic properties of graphene/g-GaN van der Waals (vdW) heterostructures. We discovered that the Dirac cone of graphene could be quite well preserved in the vdW heterostructures. Moreover, a transition from an n-type to p-type Schottky contact at the graphene/g-GaN interface was induced with a decreased interlayer distance from 4.5 to 2.5 Å. This relationship is expected to enable effective control of the Schottky barrier, which is an important development in the design of Schottky devices.

To overcome current serious energy and environmental issues, photocatalytic water splitting holds great promise because it requires only solar energy as an energy input to produce hydrogen. In this work, based on first-principle calculations, we studied the van der Waals heterostructure formed by PtS₂ and arsenene (Are) monolayers that were successfully synthesized on a large scale at high quality. From an analysis of the migration paths of photoinduced electrons and holes, a direct Z-scheme photocatalytic mechanism is demonstrated in this heterostructure. Furthermore, the PtS₂/Are direct Z-scheme heterostructure has decent band edge positions to promote the redox reaction to decompose water at pH 0. The interfacial charge difference and potential drop are presented, which further support the formation of a direct Z-scheme photocatalyst. More importantly, the PtS₂/Are heterostructure has quite high solar-to-hydrogen (STH) efficiency (49.32%), significantly enhanced compared with isolated PtS₂ (12.67%) or Are (10.34%) monolayers. This direct Z-scheme PtS₂/Are heterostructure with excellent STH efficiency suggests its promising application as a photocatalyst for water splitting.

Our investigations revealed that the structural imperfection greatly influences the electronic properties of G/WSe₂ vdW heterostructures.