Influence of rare earth co-dopant on the photocatalytic property of TiO₂ nano-particles

Abstract

A series of nanometer TiO₂ photocatalysts co-doped respectively with rare earth Er³⁺-Ce³⁺ and La³⁺-Fe³⁺ were prepared by sol-gel method, and the photocatalytic activity under ultra-violet light was evaluated by photocatalytic degradation of methyl blue. The crystallographic forms, particles size, and morphology were characterized by XRD and TEM. The results showed that the optimum heat temperature of co-doped TiO₂ was 550 °C, and the co-doped TiO₂ kept anatase. The anatase crystal had the average size of 20 nm. The co-doping caused red-shift of the UV-Vis absorption spectra and enhanced the absorption of light. Compared with the spectrum of pure TiO₂ photocatalysts, the red-shift of Er³⁺-Ce³⁺ co-doping and La³⁺-Fe³⁺ co-doping catalysts was 53 nm and 34 nm, respectively. Optimal co-doping amount for Er³⁺-Ce³⁺ was n(Er³⁺): n(TiO₂)=0.1%, n(Ce³⁺): (TiO₂)= 0.05% and La³⁺-Fe³⁺ was n(La³⁺): n(TiO₂)=0.05%, n(Fe³⁺): (TiO₂)=0.5%. Under the condition the photocatalysis properties of the samples can be enhanced. It was found that the catalytic activity correlated well with the ratio. The degradation rate of methyl blue examined at two hour of the reaction was 92.37%, and the better photocatalysis properties than the non-doped TiO₂ were obtained. The co-doped photocatalyst on methyl blue degradation follows the apparent first-order kinetics.

Keywords

nano-TiO₂ / rare earth co-doped / photocatalytic degradation / sol-gel method

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