Photocatalytic Activity of Phosphorene Derivatives: Coverage, Electronic, Optical and Excitonic properties

TL;DR

This study explores how doping phosphorene with O, S, and N enhances its photocatalytic properties, making it capable of catalyzing water splitting under visible light, with stable, semiconducting, and highly absorbent characteristics.

Contribution

It demonstrates that specific coverages of O, S, and N on phosphorene improve photocatalytic activity and stability, revealing new potential for metal-free 2D photocatalysts.

Findings

O, S, N coverages enable water splitting catalysis

Stable 0.25-0.5 ML coverages do not create midgap defect states

High optical absorption and preserved anisotropy in doped systems

Abstract

In the context of two-dimensional metal-free photocatalyst, we investigate the electronic, optical and excitonic properties of phosphorene derivatives within first-principles approach. While two-dimensional phosphorene does not catalyze the complete water splitting reactions, O, S, and N coverages improve the situation drastically, and become susceptible to catalyze the complete reaction at certain coverages. We find that for all these dopants, 0.25 -- 0.5 ML coverages are thermodynamically more stable, and does not introduce midgap defect states and the composite systems remain semiconducting along with properly aligned valance and conduction bands. Further, within visible light excitation, the optical absorption remain very high 10$^5$ cm$^{-1}$ in these composite systems, and the fundamental optical anisotropy of phosphorene remains intact. We also investigate the effect of layer thickness through bilayer phosphorene with oxygen coverages. Finally we investigate the excitonic properties in these composite materials that are conducive to both redox reactions. The present results will open up new avenues to take advantage of these metal-free phosphorene derivatives toward its outstanding potential in photocatalysis.