Metal Cocatalyst Engineering in Metal‐Semiconductor Hybrid Photocatalysts Achieves a Fivefold Enhancement of Hydrogen Evolution

This study explores the optimal morphology of photochemical hydrogen evolution catalysts in a one‐dimensional system. Systematic engineering of metal tips on precisely defined CdSe@CdS dot‐in‐rods is conducted to exert control over morphology, composition, and both factors. The outcome yields an optimized configuration, a Au−Pt core‐shell structure with a rough Pt surface ( Au@r‐Pt ), which exhibits a remarkable fivefold increase in quantum efficiency, reaching 86 % at 455 nm and superior hydrogen evolution rates under visible and AM1.5 G irradiation conditions with prolonged stability. Kinetic investigations using photoelectrochemical and time‐resolved measurements demonstrate a greater extent and extended lifetime of the charge‐separated state on the tips as well as rapid water reduction kinetics on high‐energy surfaces. This approach sheds light on the critical role of cocatalysts in hybrid photocatalytic systems for achieving high performance.