Insights into a “seesaw effect” between reducibility and hydrophobicity induced by cobalt doping: influence on OMS-2 nanomaterials for catalytic degradation of carcinogenic benzene

Abstract

OMS-2 is one of the most promising catalytic nanomaterials for the elimination of volatile organic compounds. However, water poisoning resulting from water vapor inevitably leads to the deactivation of active sites. To solve the above issue, we introduced cobalt (Co) ions into the OMS-2 framework to simultaneously tailor its surface hydrophobicity as well as its lattice oxygen activity. Density functional theory calculations were first used to demonstrate that introduction of Co ions helps improve the surface hydrophobicity of OMS-2, while leading to poor reducibility. To confirm the theoretical predictions, we established a facile strategy to obtain OMS-2 with Co doping concentrations at relatively high and low levels. Characterization analysis revealed that Co doping resulted in a decrease in the reducibility of OMS-2, whereas its surface hydrophobicity increased considerably. The catalytic test demonstrated that Co doping had an enormous influence on the catalytic activity of OMS-2 for benzene elimination, which was attributed to a “seesaw effect”, resulting from reducibility and hydrophobicity induced by Co doping. By balancing the decreased reducibility and enhanced hydrophobicity, a win–win strategy was achieved to obtain a highly efficient OMS-2 catalyst with superior water-tolerance, which is comparable to that of a commercial noble support catalyst.