Supplementary Material for Journal of Sol-Gel Science and Technology
Fabrication of luminescence-sensing films based on surface precipitation reaction of Mg-Al-Eu LDHs
Takashi Yagami, Manabu Hagiwara, Shinobu Fujihara*
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. E-mail:
Experimental
Powder samples were prepared by a hydrothermal method. Mg(NO3)2·6H2O, Al(NO3)3·9H2O, and Eu(NO3)3·6H2Owere dissolved in 50 mL of ion-exchangedwater. A total metal concentration was fixed at 0.15 M, with a cationic ratio of Mg2+ : Al3+ : Eu3+ = 2 : 0.995 : 0.005.Hexamethylenetetramine (0.13 M) was further added to the above aqueous solution, followed by stirring for 30 min at room temperature. The solution was then placed in Teflon-lined autoclaves and heated at 140 ºC for 24 h. Precipitates after the hydrothermal reaction were collected, washed with ion-exchanged water three times and additionally with ethanol two times, and dried at 60 ºC for 24 h to obtain an as-prepared powder sample (Powder A). A heat treatment of Powder A was conducted at 500 ºC for 30 min to obtain a heated sample (Powder H) for immersion experiments.Powder H (50 mg) was dispersed in one of three different liquid media; ion-exchanged water, the 0.2 M aqueous solution of sodium benzoate, or the 0.2 M aqueous solution of disodium terephthalate, followed by stirring for 24 h at room temperature. Finally the powder samples were collected, washed with ion-exchanged water two times and additionally with ethanol once, and dried at 60 ºC for 24 h to obtain Powder W (immersed in ion-exchanged water), Powder B (immersed in the aqueous solution of sodium benzoate), or Powder T (immersed in the aqueous solution of disodium terephthalate).
Film samples of the same composition (Mg2+ : Al3+ : Eu3+ = 2 : 0.995 : 0.005), which was, however, different from that employed in the main experiment, were also prepared by the sol–gel dip-coating method. Mg(NO3)2·6H2O, Al(NO3)3·9H2O, and Eu(NO3)3·6H2O were dissolved in 10 mL of ethanol. Subsequently, 1.0 g of PEG 10000 was added to the above ethanolic solution under stirring. The resultant solution was dip-coated on the silica glass substrates at the withdrawal speed of 3.0 mm s−1. The coatedsubstrates were immediately dried at 90 ºC for 10 min and then heatedat 700 ºC for 30 min in air to obtain Film A’. In the immersion experiment, Film A’ was immersed in ion-exchanged water, the 0.2 M aqueous solution of sodium benzoate, or the 0.2 M aqueous solution of disodium terephthalateat 90 ºC for 5 min to obtain Film W’, Film B’, or Film T’.
Figures
Supplementary Fig. S1. (a1) XRD patterns of the as-prepared powder (Powder A), the heat-treated powder (Powder H), and the powders immersed in water (Powder W), the benzoate solution (Powder B), and the terephthalate solution (Powder T); (a2) magnified XRD patterns for Powder W, B, and T; (b1) XRD patterns of the as-prepared film (Film A’) and the films immersed in water (Film W’), the benzoate solution (Film B’), and the terephthalate solution (Film T’); (b2) magnified XRD patterns for Film W’, B’, and T’.
Supplementary Fig. S2.FESEM images of (a) Powder A, (b) Powder H, (c) Powder W, (d) Powder B, and (e) Powder T.
Supplementary Fig. S3.PL excitation and emission spectra of PowderH, W, B, and T.
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