High Entropy Oxide-Polyoxometalate Sub-1 nm Hetero-Nanowires as Cathode Catalysts in Li–O2 Batteries

It is desirable for lithium-oxygen batteries (LOBs) to fabricate the cathode catalysts with high catalytic activity and stability. High entropy oxide (HEO) sub-1 nm nanowires (SNWs) with the nearly 100% active site exposure and intrinsic stability are doubtless one of the best candidates. Herein, under a mild solvothermal condition, by incorporating phosphomolybdic acid (PMA) into multimetal oxide reaction system, a series of HEO-PMA SNWs are successfully prepared, where the variety of metal oxides is adjustable from mono component to six components. When these SNWs as the cathode catalysts are applied to LOBs, the capacity and cycling stability of the LOBs are steadily improved with the metal oxide species increasing stepwise, indicating that the entropy modulation effect plays an important role in enhancing battery performance. Additionally, considering the difference in the intrinsic catalytic activity of various metal oxides, the battery performance is further optimized by keeping the number of elements constant in HEO-PMA SNWs and just adjusting one kind of metal oxide. Particularly, BiCuFeCeWPtO_x-PMA SNWs based battery delivers a high capacity (11206 mA h g^-1) and excellent stability for 213 cycles, making it a promising electrocatalyst candidate for LOBs.