Grafted iron(III) ions significantly enhance NO2 oxidation rate and selectivity of TiO2 for photocatalytic NOx abatement

J. Patzsch, J. N. Spencer, A. Folli, J. Z. Bloh

 RSC Adv., 8 (2018), 27674-27685, doi:10.1039/C8RA05017A


Semiconductor photocatalysis could be an effective means to combat nitrogen oxides (NOx) based air pollution through mineralisation of NOx to nitrate. However, most of the typically TiO2-based catalysts employed show a much higher reactivity towards NO than NO2, leading to an accumulation of this unwanted and toxic intermediate. By grafting the photocatalyst with small amounts (≤0.1 at%) of isolated iron(III) ions, the reactivity towards NO2 is increased by the factor of 9, bringing it up to par with the NO-reactivity and alleviating the problem with intermediate accumulation. Consequently, the observed selectivity of the reaction is dramatically increased from less than 40% to more than 90%. The paper also discusses possible mechanisms for this very beneficial behavior.

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