Strategies for Plasmonic Hot‐Electron‐Driven Photoelectrochemical Water Splitting

Abstract Photoelectrochemical water splitting (PEC‐WS) was inspired by the natural photosynthesis process that utilizes sunlight energy to produce chemical energy through splitting water to form hydrogen and oxygen. One recent promising and innovative approach in this field is to implement the concept of plasmonic to PEC‐WS devices. This Review provides a systematic overview of the plasmonic and hot‐electron‐driven PEC‐WS and elucidates their possible mechanisms for plasmon‐mediated energy transfer. In the first section, we provide a brief summary of the basics of PEC‐WS and the strategies employed to maximize its conversion efficiency. Highlighting the advantages of the plasmonic‐based PEC system, in the next part we cluster our discussion based on the basics of plasmonics and the involved energy transfer mechanisms, which are classified as radiative (scattering, optical near field coupling) and nonradiative energy transfer (hot electron injection, plasmon resonant energy transfer) processes for plasmonic metal–semiconductor junctions as a photoactive material. Then, the recent research efforts in this field are categorized and discussed in three main sections: 1) nanoplasmonic units, 2) nanostructured support scaffolds, and 3) interface engineering with state‐of‐the‐art demonstrations. Finally, we conclude our Review with pointing out the challenges and perspectives of the plasmonic‐based architectures for future water‐splitting devices.