In this work, we integrated Ag3PO4 with Bi4Ti3O12 to form Bi4Ti3O12/Ag3PO4 heterojunction nanocomposites by an ion-exchange method. The as-prepared Bi4Ti3O12/Ag3PO4 composites were systematically characterized by means of XRD, SEM, TEM, BET, XPS, UV-vis DRS, EIS, PL spectroscopy, and photocurrent response. SEM, TEM, and XPS results demonstrate the creation of Bi4Ti3O12/Ag3PO4 heterojunction with obvious interfacial interaction between Bi4Ti3O12 and Ag3PO4. PL spectra, EIS spectra, and photocurrent responses reveal that the composites display an enhanced separation efficiency of photogenerated electron-hole pairs, which is due to the charge transfer between Bi4Ti3O12 and Ag3PO4. Rhodamine B (RhB) was chosen as the target organic pollutant to evaluate its degradation behavior over Bi4Ti3O12/Ag3PO4 composites under simulated sunlight irradiation. Compared to bare Bi4Ti3O12 and Ag3PO4 nanoparticles, the composites exhibit a significantly enhanced photocatalytic activity. The highest photocatalytic activity is observed for the 10% Bi4Ti3O12/Ag3PO4 composite with 10% Bi4Ti3O12 content, which is about 2.6 times higher than that of bare Ag3PO4. The photocatalytic mechanism involved was investigated and discussed in detail.

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A carbon quantum dot (CQDs)/Ag3PO4/BiPO4 heterostructure photocatalyst was constructed by a simple hydrothermal synthesis method. The as-prepared CQDs/Ag3PO4/BiPO4 photocatalyst has been characterized in detail by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet–visible spectroscopy, and photoelectrochemical measurements. It is demonstrated that the CQDs/Ag3PO4/BiPO4 composite is constructed by assembling Ag3PO4 fine particles and CQDs on the surface of rice-like BiPO4 granules. The CQDs/Ag3PO4/BiPO4 heterostructure photocatalyst exhibits a higher photocatalytic activity for the degradation of the rhodamine B dye than that of Ag3PO4, BiPO4, and Ag3PO4/BiPO4. The synergistic effects of light absorption capacity, band edge position, separation, and utilization efficiency of photogenerated carriers play the key role for the enhanced photodegradation of the rhodamine B dye.

Based on a sonochemical route, the effect of trisodium citrate and acetic acid, which served as the structure-directing agents, on the synthesis of Ag 3 PO 4 nano/micro structures was investigated. It is found that the sample prepared at n(AgNO 3 ) = 3 mmol, n(KH 2 PO 4 ) = 2 mmol, n(Na 3 Cit) = 1 mmol and n(CH 3 COOH) = 3 mL is composed of coral-like microspheres. When varying the contents of reagents to other levels or in the absence of acetic acid, it brings about the formation of mesoporous microspheres or polyhedrons. The photocatalytic activity of the as-prepared Ag 3 PO 4 samples was evaluated by the degradation of rhodamine B (RhB) under simulated-sunlight irradiation. Compared to the mesoporous microspheres or polyhedrons, the coral-like microspheres exhibit a superior photocatalytic activity, and the degradation percentage of RhB after photocatalysis reaction for 60 min reaches 96.8%.

Ag 3 PO 4 nanospheres with an average size of 300 nm were synthesized via a sonochemical process. The electrochemical performances of the as-synthesized Ag 3 PO 4 nanospheres in aqueous KOH electrolyte with different concentrations were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The measured cyclic voltammetry curves as well as charge-discharge curves reveal a good pseudocapacitive behavior of Ag 3 PO 4 nanospheres. In a 1 M KOH electrolyte at a current density of 0.5 mA cm −2 , the speci c capacitance of Ag 3 PO 4 nanospheres is obtained to be 832 F g −1. However, Ag 3 PO 4 nanospheres exhibit an inferior charge-discharge cycling stability, which could be due to the formation of Ag 2 O during the cycling process.

Rose flower-like Bi 2 WO 6 hierarchical architectures with average diameter of 7¯m were synthesized via a hydrothermal route. The as-synthesized Bi 2 WO 6 hierarchical architectures were decorated with Au nanoparticles (20110 nm in size) by a photocatalytic reduction method. The prepared samples were systematically investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, ultravioletvisible diffuse reflectance spectroscopy, electrochemical impedance spectroscopy and photocurrent response. The photocatalytic performance of the samples was evaluated by the degradation of RhB in aqueous solution under simulated sunlight irradiation. It is observed that AuBi 2 WO 6 composite exhibits a photocatalytic activity much higher (about 2.7 times higher) than that of bare Bi 2 WO 6 . The enhanced photocatalytic activity of AuBi 2 WO 6 can be attributed to the enhanced separation of photogenerated electronhole pairs due to the electron migration from Bi 2 WO 6 hierarchical architectures to Au nanoparticles. As a result, more electrons and holes are able to participate in the photocatalytic reactions. The underlying photocatalytic mechanism was discussed.

A facile sonochemical method was used to synthesize Ag3PO4 particles and the effect of pH value, reaction temperature and reaction time on the products was investigated. It is found that the samples prepared at neutral (pH = 7) and alkaline (pH = 11) environments exhibit a similar particle morphology and size. The particles are shaped like spheres with a size distribution majorly focusing on a range of 200–450 nm, and the average particle size is about 300 nm. The sample prepared at acidic environment (pH = 3) is composed of polyhedral microparticles with size of 5–8 μm. At relatively low temperatures of 20–50 °C, the spherical nanoparticles do not undergo obvious morphology/size changes; however, when the temperature is increased up to 80 °C, the nanoparticles are aggregated to form large-sized polyhedral microparticles in the size range of 4–7 μm. Compared to the pH value and reaction temperature, the reaction time has a minor effect on the morphology of Ag3PO4 particles. RhB was chosen as the target pollutant to evaluate the photocatalytic activity of the as-prepared Ag3PO4 samples under simulated-sunlight irradiation. It is shown that the samples consisting of spherical nanoparticles exhibit an extremely high photocatalytic activity, and the degradation percentage of RhB after reaction for 50 min reaches over 90%. The samples of polyhedral microparticles have a relatively low photocatalytic activity, which is possibly due to their large particle size. Hydroxyl (.OH) radical was detected by spectrofluorimetry using terephthalic acid as a .OH scavenger and was not found to be produced over the simulated-sunlight-irradiated Ag3PO4 catalyst. The effect of ethanol, benzoquinone and ammonium oxalate on dye degradation was also investigated. Based on experimental results, the direct oxidation by h+ is suggested to the dominant mechanism toward the dye degradation.

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