Designing wide-spectrum-responsive cathode catalysts with abundant active sites for high-performance photo-enabled lithium–oxygen batteries <i>via</i> band engineering

Aprotic lithium-oxygen batteries (LOBs) have been regarded as novel energy storage devices due to their excellent specific energy density, yet the large discharge/charge overpotentials remain a formidable obstacle to be overcome. A photoassisted battery has been verified as one of the most effective approaches to reduce the overpotentials of LOBs. Herein, ZnO nanorod arrays were <i>in situ</i> grown on carbon textile, followed by <i>in situ</i> transformation to form Zn-HHTP@ZnO (HHTP, hexahydroxytriphenylene) heterojunction photocatalysts. The porous structure and conjugated system of highly conductive Zn-HHTP provide efficient electron conduction pathways, compensating for the insufficient conductivity of ZnO. The nano-array structure enables multiple scattering and reflection of incident light within the array, enhancing photon utilization efficiency. The <i>in situ</i> grown Zn-HHTP@ZnO heterojunction composite not only possesses abundant active catalytic sites but also exhibits a broad light absorption range. Consequently, the assembled LOBs with Zn-HHTP@ZnO cathode deliver a low charging potential of 3.20 V under illumination and an excellent energy efficiency of 93.4%, which is significantly higher than that of 78% under dark conditions. Therefore, this paper provides a deeper understanding of the mechanism of photoexcited charge carriers in LOBs and will facilitate further exploration of light-involved energy storage systems.