Enhancing catalytic activity for toluene and acetone oxidation over ZraCo1-aOx catalysts by doping Zr to improve the oxygen activation capacity due to formation of Zr-O-Co bonds

•Synthesis of ZraCo1-aOx oxides with core–shell structured microsphere.•Enhanced catalytic oxidation activity to toluene and acetone over ZraCo1-aOx.•Improving oxidation capacity and active oxygen content due to formation of Zr-O-Co bonds.•Rich surface adsorbed and lattice oxygen act as active species to oxidize toluene and acetone.