Preparation, characterization and photocatalytic studies of N, Sn-doped defect pyrochlore oxide KTi0.5W1.5O6

The Influence of Tin(II) Incorporation on Visible Light Absorption and Photocatalytic Activity in Defect‐Pyrochlores

“…In previous reported works concerning ione xchange with Sn II , [12,[22][23][24] the exchange reactionw as done in an acidic solution of SnCl 2 .W hile Kudo et al used 0.1 m HCl( resulting in pH 1), [12] the acid concentration has not alwaysb een reported. [22][23][24] This is especially problematic when using SnCl 2 ,s ince SnCl 2 has been reported to hydrolyse if the pH is above 1, with insoluble abhurite (Sn 21 O 6 Cl 16 (OH) 14 )b eing formed at pH above 1.5. [26] Using lower concentrated acids as solventw ould thus result in the formation of by-phases of hydrolysedt in species, which can severely influence the activity of photocatalytic materials.…”

“…Although this has been done in literature for many tin-exchanged materials, [11,23,24] the reported values for the Sn 3d 5/2 signal differ by 1.7 eV.Acloser look into the literature reveals values for the Sn 3d 5/2 signalf or SnO from 485.6 eV [35] to 487.0 eV [36] and from 486.2 eV [37] to 488 eV [38] for SnO 2 (all values relative to the C1 ss ignal at 284.8 eV). Although this has been done in literature for many tin-exchanged materials, [11,23,24] the reported values for the Sn 3d 5/2 signal differ by 1.7 eV.Acloser look into the literature reveals values for the Sn 3d 5/2 signalf or SnO from 485.6 eV [35] to 487.0 eV [36] and from 486.2 eV [37] to 488 eV [38] for SnO 2 (all values relative to the C1 ss ignal at 284.8 eV).…”

“…More problematic is the determination of the oxidation state, especially for tin. Although this has been done in literature for many tin-exchanged materials, [11,23,24] the reported values for the Sn 3d 5/2 signal differ by 1.7 eV.Acloser look into the literature reveals values for the Sn 3d 5/2 signalf or SnO from 485.6 eV [35] to 487.0 eV [36] and from 486.2 eV [37] to 488 eV [38] for SnO 2 (all values relative to the C1 ss ignal at 284.8 eV). TheS n3 ds ignals of our samples consist of as ymmetricalsignal in the overlapping region of SnO and SnO 2 literature values (Figure 7l eft), not allowing for an unambiguous assignment of oxidation states.…”

“…using SnCl 2 in hydrochloricacid, the photocatalytic activity was tested by the decomposition of methylorange and oxidationo ft erephtalic acid. [24] However,i na ll cases, the exchange was far from complete and the exact pH values were not reported. [23] Muga et al have prepared KTi 0.5 W 1.5 O 6 for organic dye degradation,a lso with acidified SnCl 2 solution.…”

“…[23] Muga et al have prepared KTi 0.5 W 1.5 O 6 for organic dye degradation,a lso with acidified SnCl 2 solution. [24] However,i na ll cases, the exchange was far from complete and the exact pH values were not reported. Moreover the use of Cl À as anion is problematic since Cl À is aw ellknown inhibitor of photocatalytic reactions.…”