Titanium functionalized α-zirconium phosphate single layer nanosheets for photocatalyst applications

Titanium species were immobilized on α-ZrP nanosheets (ZrP-Ti) using a modified post-grafting method. The obtained ZrP-Ti composites were characterized via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption spectroscopy, photoluminescence spectroscopy (PL), and scanning electron microscopy (SEM). Titanium species in the form of TiO_2-x clusters with an average particle size of 2-5 nm were grafted on α-ZrP nanosheets via chemical bonding with P element. These ZrP-Ti composites could be well dispersed in polar solvents to ensure that the TiO_2-x clusters bonded on both faces of the nanosheets were accessible. The ZrP-Ti composites presented enhanced visible-light absorption properties compared with that of pure TiO₂. These features allowed them to exhibit better photocatalytic activities for the photodegradation of methylene blue (MB) under solar irradiation. The TiO_2-x clusters tended to aggregate into anatase phase TiO₂ when the molar ratio of P/Ti exceeded 1: 1, and this reversed the advantage in their photocatalytic activities. The best MB degradation efficiency of 100% with the apparent rate constant of 0.054 min^-1 was achieved over the ZrP-Ti composite with the P/Ti molar ratio of 1: 1.