Development of a novel visible light-driven Bi2O2SiO3-Si2Bi24O40 photocatalyst with cross-linked sheet layered: The conversion of lattice oxygen to adsorbed oxygen improves catalytic activity

The heterogeneous Bi2O2SiO3-Si2Bi24O40 (BOS-BSO) photocatalyst has been prepared in situ by an environmentally friendly hydrothermal deposition. By controlling the molar concentration of the bismuth source and the silicon source (nBi:nSi) in the precursor, optimizing the heat treatment process parameters and adjusting the reaction time and temperature, the phase composition and crystallinity can be adjusted and the effective heterojunction and heterogeneity can be obtained. At the same time, the hydrothermal process forms a special 3D cross-linked sheet-like structure of bismuth silicate, which can provide graded adsorption channels for pollutants. In the BOS-600(treated at 600 °C) photocatalyst, the photocatalytic performance is 3 times and 29 times than that of BOS and P25, respectively, and excellent catalytic stability is observed even after three test cycles. Compared with the BOS powders, BOS-600 has more·OH radicals and produces·O2- on the surface which play an important role in the degradation of RhB due to the up-shift structure (Vo level). The formation of the Bi2O2SiO3-Si2Bi24O40 heterojunction in BOS-600 and the presence of oxygen vacancies caused by the highly active surface produce a synergistic effect, which significantly improve the carrier separation efficiency and increases the redox capacity of the sample.