Effects of Mn~(II) and Eu~(III) Cation Exchange in Sepiolite-Titanium Dioxide Nanocomposites in the Photocatalytic Degradation of Orange G

摘要

Two primary mechanisms of titanium dioxide (TiO2) efficiency inhibition in ultraviolet (UV)-driven photocatalytic reactions are the high recombination rate and sintering. To address these challenges, TiO2 nanocrystals were grown in-situ onto sepiolite modified with Mn~(II) and Eu~(III) ions. The resulting nanocomposites were characterized and evaluated for photocatalytic activity for Orange G (OG) degradation under UV irradiation. Resultant reduction in activity over Mn-sepiolite-TiO2 is attributed to charge-carrier scavenging by unstable Mn and adsorption- mediated chromophore protection by Mn-oxyhydroxide. Dye removal over Eu-sepiolite-TiO2 was only slightly more efficient than over the control despite relevant Eu concentrations; potentially related to inhibited TiO2-Eu interfacial synergy and superoxide radical scavenging. The results of this investigation corroborate prior observations that substrate cation-exchange results in unpredictable behavior of the cations introduced during subsequent fabrication steps which may be of benefit or detriment to the final material.