Atomically precise Pd4 cluster on monolayer MoS2 for efficient overall water splitting

Abstract

Precise atom number control in sub-nanometer Pd clusters on monolayer MoS2 offers a promising approach for simultaneously tuning geometric and electronic structures to drive both the hydrogen (HER) and oxygen (OER) evolution reactions. Herein, we systematically evaluate the photocatalytic overall water splitting performance of Pdn (n=3-6) clusters using first-principles DFT computations. The four-atom Pd cluster (Pd4) is identified as an exceptional dual-functional photocatalyst, achieving optimal thermodynamic performance with potential-limiting Gibbs free energies of 1.69 eV for OER and 0.06 eV for HER. Notably, it extends the charge carrier lifetime to 180.63 ps, 2.8 times longer than that of pristine MoS2. Electronic structure analysis reveals that the Pd4 cluster acts as an electron acceptor (+0.08 |e|), inducing intra-cluster charge polarization and creating hybrid Pd-4d/Mo-4d defect states near the Fermi level that serve as efficient channels for charge carrier transport. This work not only establishes Pd4@MoS2 as a highly active single-component photocatalyst but also proposes a general design strategy for atomically precise cluster-based materials.

Keywords: Density Functional Theory, dual-functional photocatalyst, atomically precise, Pd4 cluster, monolayer MoS2