UV–Vis-infrared light-driven thermocatalytic abatement of benzene on Fe doped OMS-2 nanorods enhanced by a novel photoactivation

Abstract

The catalysts of Fe doped cryptomelanetype octahedral molecular sieve (OMS-2, KMn8O16) with different Fe/Mn molar ratio of 0.079, 0.097, and 0.122 were prepared by a hydrothermal redox method. The Fe doping considerably enhances the catalytic activity of OMS-2 for the catalytic abatement of benzene as one of typical VOCs. The Fe doped OMS-2 catalyst exhibits much higher catalytic activity than pure OMS-2 and Pt/Al2O3 (a commercial precious metal catalyst). The considerable promotion in the catalytic activity of OMS-2 is ascribed to the significant enhancement in the lattice oxygen activity of OMS-2 induced by the Fe doping. Remarkably, under the full solar spectrum (UV–Vis-IR) illumination from a Xe lamp, the Fe doped OMS-2 catalyst exhibits high catalytic activity and excellent durability for benzene abatement. Its very high initial rate of CO2 production (rCO2, 602.2µmolmin−1g−1) is 4 and 179 times higher than that of OMS-2 and TiO2(P25) (a benchmark photocatalyst), respectively. Even under the λ>690nm visible-infrared (Vis-IR) illumination, the Fe doped OMS-2 catalyst still demonstrates high catalytic activity with the rCO2 of 44.3µmolmin−1g−1. The high catalytic activity of the Fe doped OMS-2 catalyst under UV–Vis-IR illumination derives from the efficient solar-light-driven (SLD) thermocatalysis. The SLD thermocatalysis is ascribed to the high thermocatalytic activity of the Fe doped OMS-2 catalyst and its efficient photothermal conversion because of its strong UV–Vis-IR absorption. It is found that the SLD thermocatalytic activity of the Fe doped OMS-2 catalyst is further enhanced by a novel photoactivation effect, which is completely unlike the well-known photocatalysis on photocatalytic semiconductors (e.g. TiO2).