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The novel BiPO4-BiOClxBr1−x p–n heterojunctions with adjustable band gap are successfully constructed via a facile hydrothermal method. BiPO4-BiOClxBr1−x composites were fabricated by inlaying BiPO4 particles into BiOClxBr1−x hierarchical microstructure which is composed of nanosheets. Compared with BiPO4 and BiOClxBr1−x, they exhibited significant improvement of visible light photocatalytic properties toward the degradation of RhB. The results of transient photocurrent experiments demonstrated that the significant enhancement of photocatalytic activity can be ascribed to the surface p–n junction of BiPO4-BiOClxBr1−x composites which can effectively reduce the recombination rate of the photo-generated carriers during photocatalytic process. BiPO4-BiOClxBr1−x p–n heterojunctions were possessed of tunable band-gaps by decreasing the mole ratio of Cl/Br. The highest photoactivity of the 5% BiPO4-BiOCl0.75Br0.25 heterostructure could be attributed to the synergetic effect of optimized band structure, light absorption and effective separation of electron–hole pairs. In addition, holes and superoxide radicals (•O2−) were considered to dominate the photocatalytic process. Based on the theoretical and experimental results, the reasonable photocatalytic mechanism was proposed.

The efficient visible-light-driven AgIO3/AgBr photocatalyst was successfully synthesized by an in-situ anion-exchange method at room temperature. The scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflection spectroscopy (DRS) were used to characterize the obtained samples. The photocatalytic activities of the as-prepared heterojunctions were estimated by decomposing the organic dye RhB under visible-light irradiation (λ > 420 nm). Compared with pure AgBr and AgIO3, the AgIO3/AgBr compounds showed dramatically improved visible-light photocatalytic activity. Besides, the results also revealed that 20% AgIO3/AgBr exhibited the best photocatalytic activity, which could decompose the RhB completely in 24 min. The enhanced photocatalytic activity of the composites could be ascribed to the high separation rate of the photoinduced electron–hole pairs in the heterojunction structure. Moreover, the radical trap experiments were also carried out which confirmed that h+ played the major role in RhB photodegradation. The possible mechanism of RhB degradation on the AgIO3/AgBr composite was also discussed according to the results of the experiments and the performance of the obtained photocatalysts.

BiOCl 1− x Br x solid solutions with tunable structures and morphologies were successfully synthesized both in water and ethylene glycol (EG), via a facile solvothermal process. The microstructure and properties of composites were characterized by X-ray powder diffraction (XRD), Brunauer Emmet Teller (BET), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), UV–vis spectrophotometer, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and so on. The effect on the innate character and light reaction mechanism on the photocatalytic activity of BiOCl 1− x Br x were investigated in detail by degradation of Rhodamine B (RhB). SEM revealed that rose-like BiOCl 1− x Br x solid solutions can be obtained in water and the sphere-like were synthesized in EG solvents. And the rose-like nanostructures showed superior photocatalytic properties. Furthermore, the rose-like BiOCl 0.5 Br 0.5 with high exposed {101} facets showed the highest photocatalytic activity with the RhB completely degraded within 12 min under visible light irradiation. In addition, a reasonable mechanism of the enhanced photocatalytic performance was also discussed according to the experimental results.

A novel heterojunction photocatalyst AgIO3/WO3 was fabricated through hydrothermal and chemical precipitation methods. The AgIO3/WO3 samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray detector, and UV–vis diffuse reflectance spectroscopy (UV-vis DRS). Moreover, the photocatalytic activities of AgIO3/WO3 samples were estimated by the decomposition of organic dye RhB under visible light irradiation (λ >420 nm). The result reveled that AgIO3/WO3 composite showed higher photocatalytic performance than pure AgIO3 and WO3 photocatalysts, and 50% AgIO3/WO3 heterojunction was recorded to have the optimum rate constant. The enhancement of the photocatalytic activity could be attributed chiefly to the effective separation and migration of photogenerated electron-hole pairs at the interface of AgIO3 and WO3. In addition, radical trap experiments confirmed that the ·OH was the primary reactive species during the photodecomposition of RhB. A possible photocatalytic mechanism of RhB decomposition over AgIO3/WO3 heterostructures was also presented.

In this study, the Ag3PO4 microcrystal was successfully prepared at different temperatures using precipitation and hydrothermal methods. The as-prepared products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and so on. It was found that the synthesized temperature had some effects on the morphologies and photocurrent of Ag3PO4. As the synthesized temperature increased from 20 °C to 120 °C, the ratio of exposed (110) facets increased, which are the active photocatalysis facets in Ag3PO4 crystals, along with a higher photocatalytic efficiency over RhB under visible light irradiation. And the Ag3PO4 microcrystals synthesized at 120 °C exhibited the highest photocatalytic activities with the degradation ratio of RhB rising up to 97.83% in 6 min due to the high separation efficiency of electron and hole pairs. In addition, the main active species and their roles were investigated by adding scavengers (isopropyl alcohol and EDTA) during the photocatalytic degradation of RhB and a possible mechanism was discussed.