Two-dimensional multilayer M2CO2 (M = Sc, Zr, Hf) as photocatalysts for hydrogen production from water splitting: a first principles study

Abstract

Currently, various two-dimensional (2D) monolayer materials have been predicted to be photocatalysts for water splitting. In the present work, the structural and electronic properties of 2D multilayer Zr₂CO₂, Hf₂CO₂ and Sc₂CO₂ are explored by density functional theory calculations. We found that the band gap of multilayer Zr₂CO₂ and Hf₂CO₂ becomes smaller with increasing layer number and the band edge positions demonstrate to be not suitable for driving the oxygen evolution reaction. However, applying an appropriate strain to multilayer Zr₂CO₂ and Hf₂CO₂ could make them into available photocatalysts for water splitting. For Sc₂CO₂, due to the built-in perpendicular electric field in monolayer Sc₂CO₂, there are more feasible stacking configurations of multilayer Sc₂CO₂, yet some of the multilayer Sc₂CO₂ are also proved to be potential photocatalysts for water splitting.