Water splits to degrade two-dimensional group-IV monochalcogenides in nanoseconds

TL;DR

This study reveals that water rapidly decomposes two-dimensional group-IV monochalcogenides within nanoseconds, highlighting the need to eliminate humidity during exfoliation and suggesting potential for hydrogen production applications.

Contribution

The paper demonstrates, through molecular dynamics simulations, that water dissociates quickly on these materials, a novel insight into their chemical stability and potential uses.

Findings

Water dissociates within 10 nanoseconds on these materials.

Humidity must be eliminated for successful exfoliation.

Materials can generate hydrogen ions from water without light.

Abstract

The experimental exfoliation of layered group-IV monochalcogenides --semiconductors isostructural to black phosphorus-- using processes similar to those followed in the production of graphene or phosphorene has turned out unsuccessful thus far, as if the chemical degradation observed in black phosphorus was aggravated in these monochalcogenides. Here, we document a facile dissociation of water by these materials within ten nanoseconds from room-temperature Car-Parrinello molecular dynamics calculations under standard temperature and pressure conditions. These results suggest that humidity must be fully eradicated to exfoliate monolayers successfully, for instance, by placing samples in a hydrophobic solution during mechanical exfoliation. From another materials perspective, these two-dimensional materials that create individual hydrogen ions out of water without illumination may become relevant for applications in hydrogen production and storage.