Reverse barrier layer and interfacial M-O bond reinforcement in an S-scheme high-entropy oxide heterojunction for efficient photo-assisted lithium-oxygen batteries.

Lithium-oxygen batteries (LOBs), as a promising next-generation high-energy-density system, are fundamentally limited by sluggish oxygen reduction (ORR) and oxygen evolution (OER) kinetics, resulting in high overpotentials and poor cycling stability. Herein, a p-type high-entropy spinel oxide (FeCoNiMnZnCrO x , HEO) was integrated with n-type photoactive TiO2 to construct an S-scheme heterojunction cathode (HEO@TiO2). At the heterointerface, Ti-O-M bonds (M = Fe, Co, Ni, Mn, Zn, Cr) enhance electron transport through Ti-induced electronic modulation and strengthen orbital hybridization between transition-metal 3d and O 2p, optimizing the adsorption energies of key intermediates (O2 - and LiO2) and lowering the energy barriers of the ORR/OER. Concurrently, a reverse barrier layer promotes reversible Li2O2 formation and decomposition. Additionally, a photoelectric effect accelerates charge transport and electrode kinetics, while electron enrichment on HEO amplifies the high-entropy cocktail effect. Benefiting from the synergy of high-entropy mixing, interfacial M-O bond reinforcement, and light-assisted S-scheme heterojunction, HEO@TiO2 delivers an ultrahigh specific capacity of 29 545 mA h g-1 and stable cycling over 867 cycles under dark conditions. Under illumination, an ultralow overpotential of 0.15 V is achieved, the charging rate increases by 22.4%, and Li2CO3 byproduct formation is effectively suppressed. This work presents a novel interface-coupling strategy for high-performance LOB cathodes and dual-function photo-assisted electrocatalysis.