Co-operative Influence of O2 and H2O in the Degradation of Layered Black Arsenic

TL;DR

This study uses first-principles calculations to reveal how oxygen and water collaboratively cause degradation of layered black arsenic surfaces, highlighting the importance of environmental stability for its applications.

Contribution

It provides the first detailed theoretical insight into the cooperative effects of O2 and H2O on black arsenic degradation, supported by experimental validation.

Findings

(101) surface oxidizes easily in O2

H2O reacts with oxidized surfaces to volatilize arsenic

Oxygen and water jointly accelerate degradation under ambient conditions

Abstract

Layered black arsenic (b-As) has recently emerged as a new anisotropic two-dimensional (2D) semiconducting material with applications in electronic devices. Understanding factors affecting the ambient stability of this material remains crucial for its applications. Herein we use first-principles density functional theory (DFT) calculations to examine the stability of the (010) and (101) surfaces of b-As in the presence of oxygen (O2) and water (H2O). We show that the (101) surface of b-As can easily oxidize in presence of O2. In the presence of moisture contained in air, the oxidized b-As surfaces favorably react with H2O molecules to volatilize As in the form of As(OH)3 and AsO(OH), which results in the degradation of the b-As surface, predominantly across the (101) surface. These predictions are in good agreement with experimental electron microscopy observations, thus demonstrating the co-operative reactivity of O2 and H2O in the degradation of layered b-As under ambient conditions.