Supramolecular networks stabilise and functionalise black phosphorus

Emily F. Smith,Ivan G. Timokhin,Lixu Yang,Sihai Yang,Vladimir V. Korolkov,Neil R. Champness,Peter H. Beton,Rolf Haubrichs,Martin Schröder

doi:10.1038/s41467-017-01797-6

Emily F. Smith, Ivan G. Timokhin + Show 7 more

Open Access

https://doi.org/10.1038/s41467-017-01797-6

Copy DOI

Abstract

The limited stability of the surface of black phosphorus (BP) under atmospheric conditions is a significant constraint on the exploitation of this layered material and its few layer analogue, phosphorene, as an optoelectronic material. Here we show that supramolecular networks stabilised by hydrogen bonding can be formed on BP, and that these monolayer-thick films can passivate the BP surface and inhibit oxidation under ambient conditions. The supramolecular layers are formed by solution deposition and we use atomic force microscopy to obtain images of the BP surface and hexagonal supramolecular networks of trimesic acid and melamine cyanurate (CA.M) under ambient conditions. The CA.M network is aligned with rows of phosphorus atoms and forms large domains which passivate the BP surface for more than a month, and also provides a stable supramolecular platform for the sequential deposition of 1,2,4,5-tetrakis(4-carboxyphenyl)benzene to form supramolecular heterostructures.

Highlights

The limited stability of the surface of black phosphorus (BP) under atmospheric conditions is a significant constraint on the exploitation of this layered material and its few layer analogue, phosphorene, as an optoelectronic material
We demonstrate that supramolecular networks can be formed on BP by depositing a mono-component nanoporous array of trimesic acid (TMA), and the bimolecular network formed by cyanuric acid (CA) and melamine (M)
For this study we have used crystals of BP grown by CristalTech Sàrl (Satigny, Switzerland) which were synthesised according to the protocol developed by Lange et al.[35]

Summary

Introduction

The limited stability of the surface of black phosphorus (BP) under atmospheric conditions is a significant constraint on the exploitation of this layered material and its few layer analogue, phosphorene, as an optoelectronic material. The exact mechanism of oxidation is not yet fully understood, but the presence of water and light along with oxygen facilitate surface degradation with the formation of a species of oxidised phosphorus[23, 25] This has led to several approaches to passivate the surface of both BP and phosphorene including the growth of Al2O3 on BP24, covalent attachment of phenyl groups via diazonium chemistry[26], stabilisation in specific solvents[27], and the encapsulation of phosphorene between layers of hexagonal boron nitride (hBN)[28,29,30]. In this paper we explore a new route to the solution of this problem through an investigation of the compatibility of BP with the formation of supramolecular networks which have monolayer thickness and are stabilised by noncovalent in-plane interactions, hydrogen bonding. We have demonstrated that CA.M monolayers on BP provide a stable platform for the sequential growth of additional molecular layers, for example, 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (TCPB), leading to the formation of a supramolecular heterostructure, and demonstrating the facility for further functionalisation of the BP substrate

Methods

Results

Conclusion