Plasmonic RuO ₂ Coupled with Work Function‐Tuned Cu(OH) ₂ as Cathodes for Enhanced Visible Light‐Responsive Zn‐Air Batteries

Abstract Photo‐assisted Zn‐air batteries (ZABs) can enhance the kinetics of oxygen reduction and oxygen evolution reactions (ORR/OER); however, issues like rapid charge carrier recombination and limited output voltage persist. Herein, a sandwich‐structured photo‐assisted ZABs is constructed, in which RuO ₂ is respectively coupled with a hole transport layer (HTL) (RuO ₂ ‐HTL) and an electron transport layer (ETL) (RuO ₂ ‐ETL) as the cathodes, with Zn serving as the anode in the middle. Specifically, HTL and ETL are achieved by interfacial dipoles modulating the work function of Cu(OH) ₂ , whereas photogenerated electrons and holes are originated from the plasmonic effect of RuO ₂ . In the photo‐assisted discharge process, the plasmonic‐excited holes are pumped by HTL to neutralize the electrons from the Zn anode side, thereby enhancing charge separation. The retained electrons in RuO ₂ facilitate the ORR process. On the contrary, ETL pumps the plasmon‐excited electrons to participate in the reduction of ZnO at the anode, while the holes retained by the extracted RuO ₂ accelerate the OER. This approach breaks the overpotential barrier in RuO ₂ ‐based ZABs, achieving a record‐high discharge voltage of 1.80 V and an unprecedented low charge voltage of 0.83 V. This novel cathode structure design provides an untapped pathway to obtain the high‐performance photo‐assisted batteries.