A new photocatalyst: triple heterojunction Yb3+-Bi2O3/BiOIO3 catalyst for mercury removal from flue gas

Abstract The Yb3+-Bi2O3/BiOIO3 triple heterojunction photocatalyst was successfully prepared by the EG assisted hydrothermal method and the calcination method. Bi2O3 has a variety of crystal phase structures. Through characterizations and DFT theoretical calculations, it is shown that different proportion of Yb3+ doping makes the lattice phase transition of Bi2O3. When the mole ratio of Yb3+ doping in the complex is 1%, the coexistence and recombination of α-Bi2O3, β-Bi2O3 and BiOIO3 lead to the formation of triple heterojunction and the establishment of a unique electronic transmission channel, which promote the separation of photogenerated carriers. At the same time, Yb3+ ions have unique electronic transition characteristics, which effectively broaden the spectral response range of the Yb3+-Bi2O3/BiOIO3 photocatalyst, and also improve the photocatalytic activity. Thanks to its optimized performance, the best efficiency of the Yb3+-Bi2O3/BiOIO3 triple heterojunction photocatalyst in removing gaseous Hg0 under visible light can reach 76.73%, which is much higher than that of its pure component. Finally, the mechanism of high efficiency catalytic oxidation was proposed by combining rare earth ion doping with semiconductor recombination to construct heterojunction catalysts with a wide spectral response. This work provides a new method for designing efficient photocatalysts.