Effect of excess amount of aniline for TiO2 and polyaniline composite

• Polyaniline and TiO2 composite was fabricated with an excess amount of aniline.
• The composite was separated with soluble and insoluble layers in 2-propanol.
• This result provides the minimum amount of TiO2 to dissolve in 2-propanol.
• High ratio of polyaniline leads the conducting process instead of PL process.

Polyaniline and TiO2 composite was fabricated with excess molar ratio of aniline (10 mol) against titaniumisopropoxide (Ti(OPr)4) (3.3 mol) to find out the effect of an excess amount of aniline after polymerization. The composite was separated with soluble top layer (TPTOP) and insoluble bottom layer (TPBOT). FTIR spectra of TPBOT and TPTOP showed no clear difference. However, energy dispersive X-ray spectra (EDS) showed that the titanium weight ratios are 19.51 and 9.28 wt.% for TPTOP and TPBOT, respectively. Although field emission scanning electron microscope (FESEM) image of TPTOP film showed smooth surface without particle, FESEM image of TPBOT film exhibited particular shape with a diameter of approximately 60 nm. Strong UV–vis absorption in the range of UV–vis region was observed with the increase of the amount of TiO2PAn. The photoluminescence (PL) peaks of both TPTOP and TPBOT shifted toward lower energy with increasing to the excitation wavelength, which indicated the existence of multiple luminescence centers. The PL intensities of TPTOP were much stronger than those of TPBOT, which implied that the higher ratio of polyaniline (less TiO2) led conducting process instead of a luminescence process.