Sequential growth reveals multi-spinel interface promotion for methane combustion over alumina supported palladium catalyst

•Multi-spinel NiCo2O4/NiAl2O4 interface is introduced over γ-Al2O3 support.•NiCo2O4/NiAl2O4 acts as a structural template for PdO nanoparticles growth.•NiCo2O4/NiAl2O4 strengthens interaction between alumina support and PdO.•NiCo2O4/NiAl2O4 enhances activity and stability of Pd/Al2O3 for CH4 oxidation.