Plasmonic RuO2 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.