Figure 10.

(a) The simulation model of Fe₃O₄@TiO₂@Ag and (b) Fe₃O₄@TiO₂@AuAg nanoparticles, (c) the calculated electromagnetic field distribution around Fe₃O₄@TiO₂@Ag and (d) Fe₃O₄@TiO₂@AuAg nanoparticles. The incident light wavelength was 785 nm. (e) SEM images of Fe₃O₄ spheres, (f) TEM image of Fe₃O₄@TiO₂ core–shell sphere, (g) SEM images of Fe₃O₄@TiO₂@Ag sphere, (h–j) SEM images of Fe₃O₄@TiO₂@AuAg nanospheres with various molar ratio of Ag:Au: (h) 1:2, (i) 1:1, (j) 2:1, (k–m) the corresponding TEM images, (n) SERS spectra illustrating the reduction of 4-nitrophenol to 4-aminophenol catalysed by Fe₃O₄@TiO₂@Au-Ag nanospheres. Reprinted with permission from [51]. Copyright 2016 Elsevier.