First Principles Study of Photocatalytic Water Splitting Hydrogen Production by SiI₂ Nanotubes

We use density functional theory (DFT) to calculate the optimal parameters of atomic arrangement, energy level and electronic structure of sawtooth (n, 0) nanotubes in this paper. The strain energy and formation energy data show that the coiled process of nanotubes is endothermic, and the correlation value decreases with the increase of the radius. Our study shows that the band gap width of SiI₂ nanotubes first increases and then decreases with the increase of the nanotube radius. The band gap of SiI₂ nanotubes changes from indirect to direct after the single layer is rolled into nanotubes and have appropriate band gaps for absorbing visible light. In addition, it is speculated that the disparity between the effective mass of electrons and holes can reduce charge carrier recombination. Among them, the n value 10 ~ 50 nanotubes showed redox capacity between pH = 7 and 0, and the reducing capacity increased with the increase of tube radius. In conclusion, we believe that SiI₂ nanotubes have great application potential in photocatalytic water splitting.

Visible light absorption indicate that SiI₂ nanotube should be effective photocatalysis for production of H₂ from splitting water