Promising anisotropic mechanical, electronic, and charge transport properties of 2D InN alloys for photocatalytic water splitting

Two-dimensional (2D) materials with unique physical properties lead to new possibilities in future nanomaterial-based devices. Among them, 2D structures suitable to be the solar-driven catalyst for water-splitting reactions have become excessively important since the demand for clean energy sources has increased. Apart from the conventional crystals with well-known symmetries, recent studies showed that materials with exotic decorations could possess superior features in these kinds of applications. In this respect, we report novel 2D tetrahexagonal (th-) InN crystal and its ordered alloys In0.33X0.67N (X = Al, Ga) that can be utilized as effective catalysts for water splitting reactions. Proposed structures possess robust energetic, dynamical, thermal, and mechanical stability with a versatile mechanical response. After a critical tensile strain value, all monolayers exhibit strain-induced negative Poisson's ratio in a particular crystal direction, making them half-auxetic materials. The examined materials are indirect semiconductors with desired band gaps and band edge positions for water-splitting applications. Due to their structural anisotropy, they have direction-dependent mobility that can keep the photogenerated charge carriers separated by reducing their recombination probability, which boosts the photocatalytic process. High absorption capacity in the wide spectral range underlines their potential performance. The versatile mechanical, electronic, and optical properties of 2D th-InN and its alloys, together with their remarkable structural stability, indicate that they can appropriately be exploited in the future for water splitting applications.