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

In the context of a two-dimensional (2D) metal-free photocatalyst, we investigate the electronic, optical, and excitonic properties of phosphorene derivatives within the first-principles approach. Whereas 2D 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 of these dopants, 0.25-0.5 monolayer coverages are thermodynamically more stable and do not introduce midgap defect states and the composite systems remain semiconducting along with the properly aligned valance and conduction bands. Further, within visible light excitation, the optical absorption remains 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 of 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.