Promoting oxygen electrode reaction kinetics in photo-assisted Li-O2 batteries through heterostructure design and built-in electric field construction

Li-O-2 batteries (LOBs) boast an exceptionally high theoretical energy density; however, the slow kinetics of the oxygen electrode reaction have been a significant hurdle in their advancement and practical application. In this study, a composite of bismuth oxyhalide heterojunction incorporated with metal-organic frameworks (MOFs) was engineered on carbon cloth (Zr-MOF/BiOIBr/CC) as an efficient bifunctional catalyst to enhance the oxygen electrode reaction in photo-assisted LOBs. Compared to Zr-MOF/CC, Zr-MOF/BiOIBr/CC significantly expands the light absorption spectrum of the catalyst. Furthermore, the built-in electric field in the heterojunction aids in the separation and directional movement of photogenerated carriers, thereby expediting the reaction kinetics of LOBs. Consequently, the photo-assisted LOBs with Zr-MOF/BiOIBr/CC as the cathodes display a discharge potential of 3.05 V, a low charge potential of 3.20 V, and an energy efficiency of up to 95.3%, and can sustain an extended cycle life of over 255 cycles. This study underscores the potential application of MOFs/semiconductor heterostructural materials in photo-assisted LOBs and offers insights into the systematic design of photo-assisted air batteries and other advanced semiconductors.