Phosphorene as a superior gas sensor: Selective adsorption and distinct I-V response

TL;DR

This study demonstrates that phosphorene exhibits exceptional gas sensing capabilities through selective molecular adsorption and distinct I-V responses, outperforming other 2D materials and promising broad sensor applications.

Contribution

The paper provides first-principles calculations showing phosphorene's superior gas sensing performance and its unique anisotropic I-V response to different gas molecules.

Findings

Phosphorene has high adsorption strength for CO, CO2, NH3, NO, NO2.

Distinct I-V responses depend on molecule type and crystal direction.

Transport anisotropy aligns with phosphorene's electronic structure.

Abstract

Recent reports on the fabrication of phosphorene, i.e., mono- or few-layer black phosphorus, have raised exciting prospects of an outstanding two-dimensional (2D) material that exhibits excellent properties for nanodevice applications. Here we study by first-principles calculations the adsorption of CO, CO2, NH3, NO and NO2 gas molecules on a mono-layer phosphorene. Our results predict superior sensing performance of phosphorene that rivals or even surpasses other 2D materials such as graphene and MoS2. We determine the optimal adsorption positions of these molecules on the phosphorene and identify molecular doping, i.e., charge transfer between the molecules and phosphorene, as the driving mechanism for the high adsorption strength. We further calculated the current-voltage (I-V) relation using a non-equilibrium Greens function (NEGF) formalism. The transport features show large (one to two orders of magnitude) anisotropy along different (armchair or zigzag) directions, which is consistent with the anisotropic electronic band structure of phosphorene. Remarkably, the I-V relation exhibits distinct responses with a marked change of the I-V relation along either the armchair or the zigzag directions depending on the type of molecules. Such selectivity and sensitivity to adsorption makes phosphorene a superior gas sensor that promises wide-ranging applications.