Ni3Se2/NiSe2 heterostructure nanoforests as an efficient bifunctional electrocatalyst for high-capacity and long-life Li–O2 batteries

Abstract Li–O2 batteries (LOBs) with ultrahigh theoretical energy density are regarded as the most promising next-generation candidates for energy storage and conversion devices. However, the development of LOBs is severely hindered by adverse parasitic reactions and sluggish reaction kinetics. Herein, hierarchical Ni3Se2/NiSe2 heterostructure nanoforests on Ni foam (Ni3Se2/NiSe2@NF) is designed as a high efficient bifunctional electrocatalyst for LOBs. As expected, owing to 3D hierarchically branched nanoforests structure, the Ni3Se2/NiSe2@NF electrode can build up an effective channel for mass transfer and expose sufficient active sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In addition, the strong interface interaction between Ni3Se2 and NiSe2 in the heterostructure causes distinct electron redistribution along the interface, which plays a vital role in enhancing electrocatalytic performance of Ni3Se2/NiSe2@NF. Accordingly, LOBs based on Ni3Se2/NiSe2@NF shows a high discharge specific capacity of 23,092 mA h g−1 at 500 mA g−1, a low voltage gap of 0.96 V and an improved cycling life of 500 cycles. It is worth noting that this study has a significant guidance for designing effective bifunctional electrocatalysts via constructing the heterostructure to boost oxygen electrode kinetics and improve Li–O2 battery performance.