Controllable synthesis of 3D hierarchical Co3O4 catalysts and their excellent catalytic performance for toluene combustion

Abstract Three-dimensional (3D) hierarchical Co3O4 catalysts with different morphologies are promising materials for the catalytic oxidation of toluene due to their high activity and relatively low costs. It is widely reported that the catalytic performance of Co3O4 catalyst for VOCs abatement highly depend on its mainly exposed crystal plane. Therefore, the morphology-controlled preparation of Co3O4 with preferentially exposed highly reactive plane plays crucial role in determining the catalytic activity of Co-based catalyst. In this work, we reported a facile and morphology-controlled synthesis of 3D Co3O4 catalysts with different morphologies and preferentially exposed planes. The best catalyst, the S-160 sample with the dominantly exposed {1 1 0} planes, exhibited a high catalytic activity for the total oxidation of toluene achieving a toluene conversion of T50% at 234 °C, which was 17 °C lower than that of the U sample with the mainly exposed {1 1 1} planes. The superior catalytic performance of the S-160 sample could be attributed to its specifically exposed highly reactive {1 1 0} planes, rich Oads species, good redox property as well as highly defective structure. In addition, the S-160 sample showed a stable activity during 100 h test, indicating its great potential for practical application for toluene oxidation.