Boosting Photocatalytic Water Splitting: Interfacial Charge Polarization in Atomically Controlled Core-Shell Cocatalysts

Platinum is a commonly used cocatalyst for improved charge separation and surface reactions in photocatalytic water splitting. It is envisioned that its practical applications can be facilitated by further reducing the material cost and improving the efficacy of Pt cocatalysts. In this direction, the use of atomically controlled Pd@Pt quasi-core-shell cocatalysts in combination with TiO2 as a model semiconductor is described. As demonstrated experimentally, the electron trapping necessary for charge separation is substantially promoted by combining a Schottky junction with interfacial charge polarization, enabled by the three-atomthick Pt shell. Meanwhile, the increase in electron density and lattice strain would significantly enhance the adsorption of H2O onto Pt surface. Taken together, the improved charge separation and molecular activation dramatically boost the overall efficiency of photocatalytic water splitting.