Low-Temperature Synthesis of Anatase TiO2 Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

In this work, the positively or negatively charged anatase TiO[subscript 2] nanoparticles were synthesized via a low temperature precipitation-peptization process (LTPPP) in the presence of poly(ethyleneimine) (PEI) and poly(sodium4- styrenesulfonate) (PSS). X-ray diffraction (XRD) pattern and high-resolution transmission electron microscope (HRTEM) confirmed the anatase crystalline phase. The charges of the prepared TiO[subscript 2], PEI-TiO[subscript 2] and PSS-TiO[subscript 2] nanoparticles were investigated by zeta potentials. The results showed that the zeta potentials of PEI-TiO[subscript 2] nanoparticles can be tuned from +39.47 mV to +95.46 mV, and that of PSS-TiO[subscript 2] nanoparticles can be adjusted from −56.63 mV to −119.32 mV. In comparison with TiO[subscript 2], PSS-TiO[subscript 2] exhibited dramatic adsorption and degradation of dye molecules, while the PEI modified TiO[subscript 2] nanoparticles showed lower photocatalytic activity. The photocatalytic performances of these charged nanoparticles were elucidated by the results of UV-vis diffuse reflectance spectra (DRS) and the photoluminescence (PL) spectra, which indicated that the PSS-TiO[subscript 2] nanoparticles showed a lower recombination rate of electron-hole pairs than TiO[subscript 2] and PEI-TiO[subscript 2].National Natural Science Foundation (China) (21176005