Mn-induced strengthening hybridization effect of Co–O bond for stable oxygen evolution in acidic media

•Mn-induced can strengthen hybridization effect of Co-O bond of cobalt spinel oxide.•Trace Mn in spinel oxide can effectively adjust the electronic structure of Co.•Doped Mn can improve the intrinsic activity and stability of cobalt spinel oxide.•Ligand confinement effect of CoBDC ensured the high dispersion and stability of active cobalt sites.