Internal Electric Field and Interfacial Bonding Engineered Step‐Scheme Junction for a Visible‐Light‐Involved Lithium–Oxygen Battery

Abstract Li–O 2 batteries have aroused considerable interest in recent years, however they are hindered by high kinetic barriers and large overvoltages at cathodes. Herein, a step‐scheme (S‐scheme) junction with hematite on carbon nitride (Fe 2 O 3 /C 3 N 4 ) is designed as a bifunctional catalyst to facilitate oxygen redox for a visible‐light‐involved Li–O 2 battery. The internal electric field and interfacial Fe−N bonding in the heterojunction boost the separation and directional migration of photo‐carriers to establish spatially isolated redox centers, at which the photoelectrons on C 3 N 4 and holes on Fe 2 O 3 remarkably accelerate the discharge and charge kinetics. These enable the Li–O 2 battery with Fe 2 O 3 /C 3 N 4 to present an elevated discharge voltage of 3.13 V under illumination, higher than the equilibrium potential 2.96 V in the dark, and a charge voltage of 3.19 V, as well as superior rate capability and cycling stability. This work will shed light on rational cathode design for metal–O 2 batteries.