The structure of the SPs was studied using bright field transmission electron microscopy (BFTEM), high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and scanning electron microscopy (SEM). As seen in Figure a-b, the Au nanoparticles have an average size of 15 ± 1.8 nm with a 1.5 ± 0.3 nm shell of PAH for Au@PAH nanoparticles. After mixing the Au@PAH core-shell nanoparticles with TALH, the Au@CloseSmall SPs are formed (Figure ) due to net attracting charges with formation of SPs ranging from 100 nm to 500 nm. As the amount of TALH is increased, Au@CloseLarge SPs are formed. As seen in Figure , the Au@CloseLarge SPs can attain dimensions of over a micrometer and do not fit the full field of view of the HAADF-STEM image. Upon adding even higher amounts of TALH, the SP size again decreases to between 100 nm to 500 nm, but due to the high amount of TiO2 precursor, the Au nanoparticles within the SP are arranged more distantly compared to the closely arranged structure of Au@CloseSmall and Au@CloseLarge SPs (Figure ). The space between the Au nanoparticles is now filled with a network of TiO2.