Enhancing the Photocatalytic Hydrogen Evolution Performance of the CsPbI/MoS Heterostructure with Interfacial Defect Engineering.

Developing highly efficient photocatalysts for the hydrogen evolution reaction (HER) by solar-driven water splitting is a great challenge. Here, we study the atomistic origin of interface properties and the HER performance of all-inorganic iodide perovskite β-CsPbI/2H-MoS heterostructures with interfacial vacancy defects using first-principles calculations. Both CsI/MoS and PbI/MoS heterostructures have strong binding and dipole moment, which are enhanced by interfacial iodine vacancies (). Because of the nature of type II heterojunctions, photogenerated electrons on the CsPbI side are promptly transferred to the MoS side where HER occurs, and sulfur vacancies () spoil this process, acting as surface traps. The formation energies of various defects are calculated by applying atomistic thermodynamics, identifying the growth conditions for promoting and suppressing formation. The HER performance is enhanced by forming interfaces with lower Δ values for hydrogen adsorption on the MoS side, suggesting PbI/MoS with to be the most promising photocatalyst.