A well-designed NU-1000@NiMn-LDHS (NU@LDHS) composite can offer efficient electrocatalytic performance with ultralow HER and OER overpotentials of 93 and 129 mV, respectively, at a current density of 10 mA cm-2 in 2 M KOH. Outstanding OER and HER activities of the composite could be attributed to the porosity and higher surface area of NU-1000 (NU), the layered structure of NiMn-LDHS (LDHS), abundant active sites in LDH, and synergistic interaction between NU and LDHS.