Two-dimensional III2-VI3 materials: Promising photocatalysts for overall water splitting under infrared light spectrum

Abstract Photocatalytic materials with overall water splitting utilizing infrared light are of particular interest for clean energy applications and environmental pollution. So far, few two-dimensional (2D) material has been identified to be in this class of materials without any additional tuning. Here, we demonstrate that, under infrared spectrum, 2D In 2 X 3 (X = S, Se, Te) hold great potential and advantages in overall water splitting. We reveal that In 2 X 3 monolayers are polarized semiconductors with an indirect band gap, and harbor a special band characteristic that is favorable for reducing the carrier recombination. Moreover, they exhibit excellent optical absorption under visible light spectrum. Remarkably for In 2 Te 3 monolayer, it can even be active under near-infrared region. For In 2 X 3 bilayers, the band gaps are obviously decreased, ensuring their optical absorption in infrared light region. Different from traditional photocatalysts, the intrinsic polarization of In 2 X 3 systems leads to a spontaneous built-in electric field, significantly benefiting the spatial separation of photogenerated electrons and holes and thus improving the photocatalytic efficiency.