OMS-2-based catalysts with controllable hierarchical morphologies for highly efficient catalytic oxidation of formaldehyde.

Cryptomelane-type octahedral molecular sieve (OMS-2) catalysts are currently attracting tremendous attention due to their low-cost and remarkable thermo-catalytic activity. However, it is still difficult for OMS-2 catalysts to completely degrade formaldehyde at relatively low or even ambient temperature. In this work, OMS-2 catalysts with different ratios of length to diameter were prepared and the OMS-2-s with the minim ratio of length to diameter (1-3) exhibited the best catalytic performance than the other samples. Then, the optimized OMS-2-s nanorods were loaded on the SiO2 nanofibers via a simultaneous electrospining-spray strategy. The evaluation for the dynamic catalytic activities of the samples showed that, the T50 (HCHO conversion reached to 50%) for the OMS-2/SiO2 nanofibrous membranes was decreased by 24 °C than the OMS-2-s nanorods. Furthermore, in the static experiment of HCHO decomposition, the composite membrane could achieve a catalytic efficiency of 52.3% at 25 °C, much higher than that of the OMS-2-s nanorods (45.9%). This work offers a new strategy to improve the catalytic efficiency of OMS-2 by controlling the morphology and loading of OMS-2 nanorods, and also designs a kind of advanced nano OMS-2-based nanofibrous membranes with hierarchical nanostructures for the highly efficient formaldehyde elimination during the practical application.