Two-dimensional Janus like scandium-based MXenes as photocatalysts for overall water splitting: A first-principles study

Abstract

The potential of monolayer and bilayer Sc2CO2 and Sc2CF2/Sc2CO2 heterostructures as photocatalysts for water splitting was investigated through first-principles calculations. It was confirmed that the most stable configuration of monolayer Sc2CO2 was the Janus structure, and its intrinsic electric field accelerated charge separation. The calculated band structure and band edge position revealed the electronic structures of Sc-based MXenes were suitable for the photocatalytic water splitting reaction under alkaline conditions. Overpotentials for the hydrogen and oxygen evolution reaction with photoexcited electrons and holes were verified via energy diagrams for adsorption Gibbs free energy on the surface of Sc-based MXenes. It was confirmed that the light absorption efficiency of bilayer Sc2CO2 and Sc2CF2/Sc2CO2 heterostructures are substantially higher than monolayer Sc2CO2 via dielectric function and absorption coefficient calculations. As a result, various optimized photocatalysts can be designed through surface engineering of Sc-based MXenes depending on applied conditions.