Acetonitrile-assisted exfoliation of layered grey and black arsenic: contrasting properties.

Nikolas Antonatos,Zdeněk Sofer,Petr Lazar,Vlastimil Mazánek,Jiri Sturala

doi:10.1039/c9na00754g

Abstract

In recent years, two-dimensional monoelemental nanostructures beyond graphene have received great attention due to their outstanding properties. Out of these elements, only arsenic is known to form different allotropes with a layered structure in the bulk form. Orthorhombic arsenic, also termed “black arsenic”, is a metastable form of arsenic with a structure analogous to that of black phosphorus and rhombohedral arsenic is known as “grey arsenic”. Here, we compare the exfoliation of black and grey arsenic in acetonitrile in high yield forming stable colloidal solutions of exfoliated materials. Together with the exfoliation procedure, detailed structural and chemical analyses are provided and potential applications in gas sensing and photothermal absorption are demonstrated for potential future arsenic-based devices.

Highlights

Two-dimensional (2D) layered materials, such as graphene,[1,2,3] hexagonal boron nitride (h-BN),[4,5] transition metal dichalcogenides (TMDs)[6,7,8,9] and monoelemental 2D materials like black phosphorus[10,11,12] have attracted signi cant attention due to their unique properties and large application potential
The morphology of bulk grey and black arsenic used for exfoliation is shown in Fig. S3.† On both materials a layered structure is clearly observed with small pieces due to the materials having been mechanically ground prior to the measurements
SEM images revealed the existence of ordered stacked layers for both arsenic samples while structural characterization con rmed the orthorhombic and rhombohedral structures of black and grey arsenic before and a er exfoliation. Both exfoliated samples were tested for potential applications in photothermic absorption and as impedimetric sensors of volatile organic compounds (VOCs)

Summary

Introduction

Two-dimensional (2D) layered materials, such as graphene,[1,2,3] hexagonal boron nitride (h-BN),[4,5] transition metal dichalcogenides (TMDs)[6,7,8,9] and monoelemental 2D materials like black phosphorus[10,11,12] have attracted signi cant attention due to their unique properties and large application potential. There has been extensive research in the eld of multi-elemental 2D materials, and currently monoelemental 2D materials beyond graphene have reemerged in the vanguard of materials research.[13] While graphene, silicene, germanene and phosphorene have been extensively studied in recent years,[12,14] arsenene, antimonene and bismuthene have been mostly explored using theoretical calculations.[14,15,16,17,18,19,20] Especially for arsenene and its experimentally synthetic methods, there have been a limited number of reports. The group V, called pnictogens, elemental layered materials have been characterized as promising 2D materials with semiconducting properties.[21,22] Black phosphorus (BP) holds an orthorhombic crystalline form and the P atoms are positioned into hexagonal puckered layers held together by van der Waals forces.[23] This structural allotrope is the thermodynamically most stable form of phosphorus, its kinetic barrier makes it synthesis difficult and challenging (Fig. 1a). Heavier pnictogens, namely As, Sb and Bi, crystallize into a rhombohedral crystal structure which is their most thermodynamically stable allotropic form (Fig. 1b), despite the existence of other allotropes including the true van der Waals layer orthorhombic form.[22]

Methods

Results

Conclusion