Janus XYTe2 monolayers and GaInTe2 bilayer: promising materials for photocatalytic water splitting - a first-principles study

The quest for efficient photocatalysts for solar-driven water splitting is paramount for advancing clean hydrogen energy. Here, we systematically investigate a novel family of 2D Janus XYTe 2 (X = Al, Ga; Y=Ga, In; X≠Y) monolayers and bilayer GaInTe 2 , using first-principles calculations. Our investigations reveal that the designed monolayers possess robust dynamic, thermal, and mechanical stability. They possess suitable band gaps (1.88–2.46 eV), high visible-light absorption coefficients, and appropriate band edge alignment for photocatalytic water splitting. Notably, GaInTe 2 monolayer achieves a high solar-to-hydrogen (STH) efficiency of ∼21.5 %. More strikingly, stacking GaInTe 2 into a bilayer with an AB2 configuration dramatically enhances its performance. The bilayer exhibits a reduced bandgap (1.36 eV), significantly boosted optical absorption across the visible spectrum, and achieves an ultrahigh theoretical STH efficiency of 42.21 %. Furthermore, Gibbs free energy change calculations provide evidence for the thermodynamic accessibility of the HER in these systems. The outcomes of our analysis establish the Janus XYTe 2 family, with special emphasis on the AB2-stacked GaInTe 2 bilayer, as an exceptional system for pioneering next-generation solar energy conversion.