An efficient red phosphor, BaMoO₄:Pr³⁺, has been fabricated by a convenient solid-state method. A strong red emission centered at 643 nm corresponding to the ³P₀→³F₂ transition of Pr³⁺ is observed under 430–500 nm excitation. In addition, improvement of the intensity of the red emission has been achieved by adding an alkali chloride to the BaMoO₄:Pr³⁺ phosphor samples, this being explained by a charge compensation mechanism. The influence of the sintering temperature on the luminescence properties of the phosphors is also discussed.

Three series of BiOM_xR_1−x (M, R = Cl, Br, I) solid solutions were systematically synthesized through a low-temperature precipitation. These solid solutions were characterized by XRD, FESEM, TEM, EDS, UV-vis spectra, nitrogen sorption/desorption, and PL. The tunable band gaps of the as-prepared solid solutions were realized via only changing the molar ratio of two halide ions. Meanwhile, the influence of citric acid in the formations of controllable morphological structures was discussed to study the growth mechanism of solid solutions. The photocatalytic activities of the bismuth oxyhalide solid solutions have also been investigated by the degradation of Rhodamine-B (RhB) under visible light irradiation. The optimized solid solutions possess higher photocatalytic activity than pure ones [BiOM (M = Cl, Br, I)] due to the broadened range of visible light response and the reduced recombination rate of electron–holes pairs. The results show that the synthesis of BiOM_xR_1−x (M, R = Cl, Br, I) solid solutions have profound significance for the design of the novel photocatalyst materials.

Hollow/flower-like BiOI microspheres have been prepared through a facile precipitation route in a water–ethanol mixed solution with the assistance of PVP and citric acid (CA) at low temperature (70 °C). The obtained products were characterized by a range of methods such as XRD, FESEM, TEM, UV-vis, DRS, PL and nitrogen sorption. A three-stage growth mechanism of such hierarchical hollow/flower-like microstructures has been proposed by observing the XRD analysis and FESEM of the intermediate products at different reaction times. Interestingly, the structure of BiOI from hollow to flower-like could be obtained by only adjusting the different amounts of reagents in the reaction system. The photocatalytic activities of the hollow/flower-like microspheres were evaluated by the degradation of RhB under visible-light irradiation, compared with the nanoplate sample and P25. Although the hollow BiOI microspheres had a higher specific surface area, the flower-like BiOI microspheres exhibited much higher adsorption and photocatalytic activities than the former. This controllable morphology method and particular properties of BiOI hierarchical microstructures could be used to synthesize bismuth-based semiconductors or other structure-controllable materials and to explore remarkable potential applications of their photocatalytic degradation ability.

Iodine-incorporated BiOCl (I–BiOCl) core–shell microspheres were for the first time fabricated using a one-step approach under atmospheric pressure. The morphology and compositional characteristics of the 3D hierarchitectures (HAs) of BiOCl were investigated by various techniques such as XRD, FESEM, TEM, EDS, XPS and PL. On the basis of observing the structure of BiOCl and iodine-containing BiOCl at different intervals of reaction time, a three-stage growth mechanism that involves an initial Ostwald ripening process followed by a self-assembly process is proposed. Meanwhile, iodine anions were utilized as both structure-directing agents for fabricating hollow, core–shell, solid structure and doped ions incorporated into the framework of the core–shell BiOCl spheres to extend the light adsorption edge to the visible light region. UV-vis spectra reveal that the band energies of the iodine anions-modified BiOCl (I–BiOCl) hierarchical hollow, core–shell, and solid samples (2.43 eV, 2.28 eV and 2.04 eV, respectively) exhibit obvious red-shifts with respect to that of the pure hollow BiOCl sample (3.23 eV). I–BiOCl without adding poly(vinylpyrrolidone) (PVP) was researched. This result demonstrated that the formation of the core–shell structure is induced by a synergetic effect by iodine and PVP. The specific surface area and porosity of the iodine anions-modified hierarchical BiOCl were also investigated by using nitrogen adsorption–desorption isotherms. The as-prepared I–BiOCl core–shell microspheres showed much higher photocatalytic activity than that of the reported TiO_2−x−yN_xF_y(SC)-3 and Bi₂WO₆, which was evaluated by the degradation of phenol under visible light (λ > 420 nm) and Rhodamine-B (RhB) dye under visible light (λ > 420 nm) and sun-light irradiation.