β particles enhance the modulating lattice distortion of Mn-doped BiFeO3 and photo-responsive catalyzing of As(III) and Sb(III)

In this work, metal Mn was doped into BiFeO3(BFO) to modulate the lattice, and a high-energy β electron beam was used to irradiate the Mn-BiFeO3(BFMO) to produce lattice distortions, resulting in reducing the photogenerated carrier complexation rate of the material and improving the photocatalytic activity for arsenic and antimony. The physical properties of the BFMO with lattice distortion also produced some changes, with the Bi: O ratio on the surface decreasing from 1.0: 3.0 to 1.0: 1.6 and the band gap decreasing from 1.5 eV to 1.3 eV. In addition, the experiment results show that the structure of Bi-Mn-Fe-O can efficiently enhance the photocatalytic oxidation of As(III) and Sb(III) at different initial pH values, and the elimination rates of As(III) and Sb(III) can reach 100% and 79.9%, respectively. Characterization by PL, Mott-Schottky, transient photocurrent response and DFT calculations demonstrated that BFMO-450 (irradiated at a dose of 450 KGy) has an excellent charge mobility, which is conducive to the separation and transfer of photogenerated carriers. The XPS results showed that the BFMO-450 surface has optimal Mn4+/Mn2+ and Fe2+/Fe3+ ion pairs, and the formation of the Fe-Mn structure is favorable for the generation of superoxide radicals (·O2-, whereas the most prominent radicals in the photocatalytic process are the ·O2-, which was proved by the electron paramagnetic resonance (EPR) and bursting experiments. This study provides a novel approach to modifying BFMO composites and demonstrates that materials possessing lattice distortion have advantages in treating heavy metal contaminated water.