Design and evaluation of Y2Te2I2 monolayer: A promising 2D photocatalytic water splitter

To search for photocatalytic water splitting materials with high carrier mobility, we construct a novel twodimensional (2D) material structure and perform first-principles calculations to assess the stability of the Y2X2I2 (X = S, Se, Te) monolayers. We select the Y2Te2I2 monolayer for subsequent calculations related to photocatalytic water splitting. Computational results indicate that the Y2Te2I2 monolayer possesses a band gap of 2.26 eV, with significant d-p orbital contributions at the conduction band minimum (CBM) and valence band maximum (VBM), facilitating efficient visible light absorption and charge separation, thereby enhancing its photocatalytic water-splitting performance. A particularly notable property is its exceptionally high carrier mobility, reaching 83,989.32 cm2V- 1s- 1 under standard conditions. In aqueous environments, this mobility can increase to 217,711.26 cm2V- 1s- 1, greatly surpassing that of recently studied 2D photocatalytic materials. Furthermore, it enables photocatalytic water splitting under visible light. It demonstrates excellent hydrogen evolution reaction (HER) performance, with a hydrogen adsorption energy of only 0.36 eV during HER. Its solarto-hydrogen (STH) efficiency is 17.59%, significantly exceeding the commercial production standard of 10%. Based on these findings, the Y2Te2I2 monolayer theoretically functions as an outstanding 2D photocatalytic material for water splitting.