Manipulate photocatalytic overall water splitting performance of the Sc2CCl2/SiSe heterostructure by S impurity: Insight from Gibbs free energy and carrier nonadiabatic dynamics

Abstract

Numerous photocatalytic hydrogen and oxygen evolution reactions (HER and OER) with heterostructures are reported but have no practicality because the less sophisticated heterostructures have no enough driving force to overcome the Gibbs free energy necessary for the spontaneous proceed of these reactions. Here, we demonstrate that these reactions with the Sc2CCl2/SiSe heterostructure can be manipulated to spontaneously proceed by S atom impurity. Based on the electronic properties by the first-principles calculations, the direct Z-scheme of the photocatalytic HER and OER with the Sc2CCl2/SiSe and S-doped Sc2CCl2/SiSe heterostructures are constructed. The calculated Gibbs free energies confirm that OER cannot spontaneously proceed with Sc2CCl2/SiSe heterostructure but can proceed with the S-doped Sc2CCl2/SiSe heterostructures, and HER can spontaneously proceed with all heterostructures. The maximum solar-to-hydrogen efficiencies of the latter can reach 11.48 %, indicating that the photocatalytic performance is maintained. Moreover, the nonadiabatic molecular dynamics results reveal the prolonged lifetimes of the photogenerated carriers, indicating the redox ability is well protected. Therefore, the S atom impurity enables the Sc2CCl2/SiSe heterostructure to be a promising candidate for developing catalysts for photocatalytic overall water splitting.