Designing a Dipole-Scheme Heterostructure Based on Janus TMDCs for Highly Efficient Photocatalytic Overall Water Splitting

Direct Z-scheme heterostructures, with strong redox abilities, are promising candidates for solar-driven water splitting. However, carriers' recombination at the interface results in the loss of at least half of the photogenerated carriers, leading to low efficiency of carrier utilization. To solve this issue, a novel dipole-scheme for photocatalytic water splitting is proposed, by utilizing the synergistic effects of the intrinsic dipole in Janus materials and the interfacial electric field. This approach can separate the photogenerated carriers with strong redox ability and suppress the recombination of photogenerated carriers at interface. Density functional theory calculations indicate that, for the heterostructures including Janus materials, the total electric dipole points to the oxygen evolution photocatalyst from the hydrogen evolution photocatalyst decreases the redox potential for water splitting. Additionally, the opposite intrinsic dipole of two Janus layers can offset the total dipole of Janus heterostructure to obtain a moderate vacuum level difference & UDelta;V for reducing the redox potential. Based on these findings, a highly efficient dipole-scheme photocatalyst CrSSe-CrSeTe (Se-Te interface), with opposite intrinsic Janus dipole is predicted, which achieves a high solar-to-hydrogen efficiency of 44%. This study provides a promising avenue for the design of highly efficient photocatalysts for overall water splitting with potential commercial applications.