Phosphorene, an emerging two-dimensional material, has received considerable attention due to its layer-controlled direct bandgap, high carrier mobility, negative Poisson's ratio and unique in-plane anisotropy. As cousins of phosphorene, 2D group-VA arsenene, antimonene and bismuthene have also garnered tremendous interest due to their intriguing structures and fascinating electronic properties. 2D group-VA family members are opening up brand-new opportunities for their multifunctional applications encompassing electronics, optoelectronics, topological spintronics, thermoelectrics, sensors, Li- or Na-batteries. In this review, we extensively explore the latest theoretical and experimental progress made in the fundamental properties, fabrications and applications of 2D group-VA materials, and offer perspectives and challenges for the future of this emerging field.

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201902352. 2D phosphorene, arsenene, antimonene, and bismuthene, as a fast-growing family of 2D monoelemental materials, have attracted enormous interest in the scientific community owing to their intriguing structures and extraordinary electronic properties. Tuning the monoelemental crystals into bielemental ones between group-VA elements is able to preserve their advantages of unique structures, modulate their properties, and further expand their multifunctional applications. Herein, a review of the historical work is provided for both theoretical predictions and experimental advances of 2D V-V binary materials. Their various intriguing electronic properties are discussed, including band structure, carrier mobility, Rashba effect, and topological state. An emphasis is also given to their progress in fabricated approaches and potential applications. Finally, a detailed presentation on the opportunities and challenges in the future development of 2D V-V binary materials is given.

Two-dimensional (2D) antimonene is a promising anode material in sodium-ion batteries (SIBs) because of its high theoretical capacity of 660 mAh g and enlarged surface active sites. However, its Na storage properties and sodiation/desodiation mechanism have not been fully explored. Herein, we propose the sodiation/desodiation reaction mechanism of 2D few-layer antimonene (FLA) based on results acquired by in situ synchrotron X-ray diffraction, ex situ selected-area electron diffraction, and theoretical simulations. Our study shows that the FLA undergoes anisotropic volume expansion along the a/b plane and exhibits reversible crystalline phase evolution (Sb ⇋ NaSb ⇋ NaSb) during cycling. Density-functional theory calculations demonstrate that the FLA has a small Na-ion diffusion barrier of 0.14 eV. The FLA delivers a larger capacity of 642 mAh g at 0.1 C (1 C = 660 mA g) and a high rate capability of 429 mAh g at 5 C and maintains a stable capacity of 620 mA g at 0.5 C with 99.7% capacity retention from the 10th to the 150th cycle. Considering the 660 mAh g theoretical capacity of Sb, the electrochemical utilization of Sb atoms of FLA is as high as 93.9% at a rate of 0.5 C for over 150 cycles, which is the highest capacity and Sb utilization ratio reported so far. Our study discloses the Na storage mechanism of 2D FLA, boosting promising applications of 2D materials for advanced SIBs.

This review explores the fundamentals of 2D bismuth, its improved fabrication methods, and its theoretical–experimental achievements in energy-related applications.

Bismuth has garnered tremendous interest for Na-ion batteries (NIBs) due to potentially high volumetric capacity. Yet, the bismuth upon sodiation/desodiation experiencing structure and phase transitions remains unclear, which sets a challenge for accessing nanotechnology and nanofabrication to achieve its applicability. Here, we use in situ transmission electron microscopy to disclose the structure and phase transitions of layered bismuth (few-layer bismuth nanosheets) during Na+ intercalation and alloying processes. Multistep phase transitions from Bi → NaBi → c-Na3Bi (cubic) → h-Na3Bi (hexagonal) are clearly identified, during which the Na+ migration from interlayer to in-plane evokes the structure transition from ABCABC stacking type of c-Na3Bi to ABABAB stacking type of h-Na3Bi. It is found that the metastable c-Na3Bi devotes to buffer the dramatic structure changes from thermodynamic stable h-Na3Bi, which unveils the origin of volume expansion for bismuth and has important consequences for 2D in-plane structure. As the lateral ductility can efficiently alleviate the in-plane mechanical strain caused by the Na+ migration, the few-layer bismuth nanosheet exhibits a potential cyclability for NIBs. Our findings will encourage more attention to bismuthene as a novel anode material for secondary batteries.

Inspired by successful synthesis of layered SiP single crystals in experiments, we explore their structures, electronic properties, and stability using first-principles calculations. The interlayer interaction in layered SiP crystal is weak, thus mechanical exfoliation is viable. We find that SiP undergoes a transition from an indirect band gap to a direct band gap of 2.59 eV when thinned from bulk to a monolayer. Our calculations also show that SiP monolayers are both dynamically and thermodynamically stable even at elevated temperatures. Monolayer SiP, with simultaneously high stability and a large direct band gap, is a promising candidate for two-dimensional blue light emitting diodes.

The performance limits of monolayer arsenic‐phosphorus (AsP) field‐effect transistors (FETs) are explored by first‐principles simulations of ballistic transport in nanoscale devices. The monolayer AsP holds a direct bandgap of 0.92 eV with significantly anisotropic electronic properties. Transfer characteristics of n‐type and p‐type AsP FETs are thoroughly investigated by scaling channel length in the armchair and zigzag direction, respectively. The simulation results indicate that AsP FETs exhibit exceptional device characteristics, such as high on‐state current, short delay time, and low power consumption. Moreover, transfer characteristics demonstrate superior anisotropy on in‐plane electrical transport properties. In particular, in the zigzag direction, even if the channel length is scaled down to 4 nm, the device performance still can satisfy the International Technology Roadmap for Semiconductors high‐performance requirement. Finally, through benchmarking energy‐delay product against other typical 2D FETs, AsP FETs are revealed to be strongly competitive 2D FETs.

Downsizing alloy anode materials has been demonstrated as an efficient strategy to alleviate volume expansion and prolong the cycling performance for lithium (Li) ion storage.