Engineering the core shell structure CoMnOx@OTS cubic catalyst with excellent water resistant for low-temperature catalytic combustion of VOCs

The design of core-shell structure catalysts with excellent activity, stability and water resistance is one of the effective strategies to realize their application in catalytic combustion of VOCs. Since octadecyltrichlorosilane (OTS) is an excellent hydrophobic coating, it was used to prepare superhydrophobic surfaces by forming hydrophobic monolayers on the surface of CoMnOx nanostructured templates. The CoMnOx@OTS core-shell structures were successfully constructed by overcoating OTS on the surface of CoMnOx-MOF nanocube and evaluated the catalytic combustion of toluene. The thickness of CoMnOx@OTS cubic crystal was adjusted by controlling the content of OTS (2 wt%, 4 wt% and 10 wt%). Due to the synergistic effect between CoMnOx and OTS, CoMnOx@OTS-1 exhibited the superior catalytic activity, stability and water resistance. The CoMnOx@OTS-1 catalytic activity was consistently maintained at about 90% in the presence of 5 vol% H2O. The content of OTS hydrophobic layer at 2 wt% reached the optimum water resistance. This is mainly attributed to the role and contribution of the hydrophobic functional group -OH from the OTS surface, which can greatly prevent the adsorption of water molecules on the active site. This work reveals new ideas for the preparation of core-shell structured cubic crystal by hydrophobic layer-coated bimetallic oxides, as well as a deeper understanding of the catalytic oxidation of toluene.