Tuning the photocatalytic water-splitting performance with the adjustment of diameter in an armchair WSSe nanotube

Abstract

Due to the enigmatical electrostatic potential difference between the inside and outside layers, the relationship between the diameter and the photocatalytic property of the Janus transition metal dichalcogenides nanotube is still unclear. In this job, for the first time we calculate the electrostatic potential difference of the Janus WSSe armchair nanotubes with corresponding building block models through the first principles calculations. The electrostatic potential difference increases as the diameter increases. Then, it is observed that the WSSe armchair nanotubes with smaller diameter have stronger oxidation capacity, weaker reduction capacity, and higher solar-to-hydrogen conversion efficiency. Furthermore, the diminution of diameter could make the band gap drop, and even cause a direct–indirect transformation of band structure. The adjustment of diameter could also regulate the ability of adsorbing water molecules at the insider and outside layers. Moreover, the suitable band edge positions, wide optical absorbance region (to the near-infrared), outstanding solar-to-hydrogen efficiency (up to 28.99%), high carrier separation, adequate photoexcited carrier driving forces, as well as the energetic and thermal stability, render these nanotubes befitting the photocatalytic water-splitting application. Our study not only predicts a kind of ideal water-splitting photocatalyst, but also shows an effective way to improve their photocatalytic performances.