In recent years, some important research indicated that the visible-light activity of photocatalysts could be enhanced via incorporating p-block non-metal elements into the lattice. In this paper, we investigated the electronic structures of pure and different non-metal （C, N, S, F, Cl, and Br） doped α-Bi2O3 using first-principles calculations based on the density functional theory. The band structures, the electronic densities of states, and the effective masses of electrons and holes for doped α-Bi2O3 were obtained and analyzed. The N and S dopings narrowed the band gap and reduced the effective mass of the carriers, which are beneficial for the photocatalytic performance. The theoretical predication was further confirmed by the experimental results.
Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO lattice and manipulate the magnetic properties of Mn-doped ZnO. Mn ions initially enter into interstitial sites and a Mn3＋ 06 octahedral coordination is produced in the prepared Mn-doped ZnO sample, in which the nearest neighbor Mn3＋ and 02 ions could form a Mn3＋-O2--Mn3＋ complex. After H2 annealing, interstitial Mn ions can substitute for Zn to generate the Mn2＋O4 tetrahedral coordination in the nanocrystals, in which neighboring Mn2＋ ions and H atoms could form a Mn2＋-O2--Mn2＋ complex and Mn-H-Mn bridge structure. The magnetic measurement of the as-prepared sample shows room temperature paramagnetic behavior due to the Mn3＋-O2--Mn3＋ complex, while the annealed samples exhibit their ferromagnetism, which originates from the Mn-H-Mn bridge structure and the Mn-Mn exchange interaction in the Mn2＋-O2--Mn2＋ complex.
The metastable γ-Bi2O3 photocatalysts with different morphologies were fabricated by means of a chemical precipitation method. The microstructure of as-prepared samples was characterized by X-ray diffraction, transmission electron microscopy and ultraviolet-visible diffusion reflectance spectroscopy. The photocatalytic performance of Bi2O3 powder was evaluated using rhodamine B as a model pollutant under visible light irradiation. The visible light photocatalytic activity of Bi2O3 with different morphologies is as follows, nanorod 〉 nanorod/nanoflake 〉 N doped TiO2 〉 irregular particle 〉 agglomerated particle. The γ-Bi2O3 shows the best photocatalytic performance and it can effectively degrade 97% RhB within 60 min.
Weichang HaoYuan GaoXi JingWen ZouYan ChenTianmin Wang
Bismuth-based compounds have been regarded as an important class of visible-light photocatalysts due to their special electronic structures. In this paper, iodide ions are introduced to modify bismuth-based compound, Bi（24）O（31）Br（10）, forming a Bi（24）O（31）Br（10）/BiOI heterojunction structure. A significant enhancement of photocatalytic activity compared to the parent compounds is observed in de-coloration of rhodamine B（Rh.B） solution. The improved photocatalytic property of Bi（24）O（31）Br（10）/BiOI heterojunction is ascribed to the unique electronic structure consisting of complementary band structures of BiOI and Bi（24）O（31）Br（10）.Iodide ions are regarded as an effective reagent to construct bismuth-based photocatalytic heterojunctions with improved photocatalytic activity.
Xi LouJun ShangLiang WangHaifeng FengWeichang HaoTianmin WangYi Du
