Synthesis,performance and action mechanism of carbon black/Ag3PO4 photocatalysts

Novel carbon black (CB)/Ag₃PO₄ compound photocatalysts were synthesized from a hydrothermal method and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and electrochemical methods. The photocatalytic oxidation ability of CB/Ag₃PO₄ was evaluated through methyl orange degradation experiments under visible light irradiation. The CB/Ag₃PO₄ showed higher photocatalytic activity than pure Ag₃PO₄. It was indicated the compound catalysts could absorb and utilize more optical energy to improve the photocatalytic activity, which was attributed to the ability of carbon black to accelerate the electron-hole separation. In particular, the methyl orange photocatalytic degradation rate over the 7?mg/L CB/Ag₃PO₄ was 1.6 times that of Ag₃PO₄. And the results of the cyclic experiment show that the photocatalyst has good stability. Moreover, the mechanism about the photocatalytic activity of CB/Ag₃PO₄ compounds was investigated. In this photocatalytic reaction, ?OH was the major active substrate responsible for the visible-light-driven degradation.     

Ultrasound-assisted synthesis of high-efficiency Ag3PO4/CeO2 heterojunction photocatalyst

The Ag₃PO₄/CeO₂ heterojunction photocatalyst prepared by an ultrasound-assisted method exhibits an enhanced photocatalytic activity compared to pure Ag₃PO₄, CeO₂, and Ag₃PO₄/CeO₂ obtained without ultrasound action. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and ultraviolet–visible absorption spectroscopy (UV–vis), and the effects of ultrasound on the physicochemical properties and photocatalytic activity of Ag₃PO₄/CeO₂ are discussed. Results show that the ultrasound-assisted synthesis method significantly improves the photocatalytic ability. The mechanism about the improvement was discussed in details.     

Photocatalytic degradation of bisphenol A and dye by graphene-oxide/Ag3PO4 composite under visible light irradiation

A facile, one-step synthesis of graphene-oxide (GO)/Ag₃PO₄ was prepared. The as-prepared samples were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS) and fourier transformed infrared (FT-IR) spectroscopy. The SEM image indicated that Ag₃PO₄ particles were mainly distributed on the surface of GO sheets uniformly. DRS analysis revealed that the samples had good visible light response. The photocatalytic activity of the composites was evaluated by the degradation of Rhodamine B (RhB) and Bisphenol A (BPA). The results indicated that the photocatalytic performance of GO/Ag₃PO₄ was greatly enhanced after introduction of GO. The photocatalytic degradation efficiency of colorless chemical pollutants (BPA) over GO/Ag₃PO₄ was higher than that of Ag₃PO₄, and the possible degradation path was proposed by liquid chromatography mass spectrometry (LC-MS) analysis. Moreover, the photocatalytic stability was discussed by XRD and FT-IR spectroscopy analysis. Based on the experimental results, a possible visible-light photocatalytic degradation mechanism was also discussed.     

Ag3PO4 quantum dots sensitized AgVO3 nanowires: A novel Ag3PO4/AgVO3 nanojunction with enhanced visible-light photocatalytic activity

Ag₃PO₄/AgVO₃ heterojunctions with high photocatalytic activities were synthesized via a simple and practical low-temperature solution-phase route by using AgVO₃ nanowires as substrate materials. The as-prepared Ag₃PO₄/AgVO₃ heterojunctions included Ag₃PO₄ quantum dots assembling uniformly on the surface of AgVO₃ nanowires. Compared with pure AgVO₃ nanowires, Ag₃PO₄/AgVO₃ composite photocatalysts exhibited enhanced photocatalytic activities under visible light irradiation in the decomposition of 4-chlorophenol (4-CP) ethanol solution. The enhanced performance is believed to be induced by the high specific surface area, strong visible-light absorption originating from the quantum dot sensitization of Ag₃PO₄, and high efficient separation of photogenerated electron–hole pairs through Ag₃PO₄/AgVO₃ heterojunction.     

Photocatalytic degradation of Basic Blue 41 dye under visible light over SrTiO3/Ag3PO4 hetero-nanostructures

In an attempt to develop nanostructured photocatalysts with high performance, SrTiO₃/Ag₃PO₄ hetero-nanostructures were successfully fabricated. The formed binary heterojunctions were composed of SrTiO₃ nanotubes prepared using liquid-phase deposition, and Ag₃PO₄ nanoparticles prepared using a sol–gel method. Synthesis details, including morphology, structure, and optical properties of the prepared photocatalysts, were characterized and comparatively discussed. The results showed that at an optimal ratio of SrTiO₃ to Ag₃PO₄ (20–80), the photocatalytic degradation of Basic Blue 41 under 80-min visible light irradiation is the maximum amount of 99%, which is about 4.4 and 1.5 times higher than that of pristine SrTiO₃ nanorods and Ag₃PO₄ nanoparticles, respectively. It can be due to the synergistic effect of two materials that provide high light absorption and charge carriers’ separation. Finally, a detailed possible mechanism for enhancing the photocatalytic activity of the SrTiO₃/Ag₃PO₄ hetero-nanostructures was proposed.     

BiOCl/Ag3PO4 Composites with Highly Enhanced Ultraviolet and Visible Light Photocatalytic Performances

The BiOCl/Ag₃PO₄ composites have been prepared via a facile and reproducible route. In the composite, Ag₃PO₄ particles are deposited on the surface of plates of BiOCl. Among the as‐prepared samples, the ultraviolet (UV) and visible light photocatalytic reaction rates of BiOCl/Ag₃PO₄ composite with the ratio of 1:0.1 are about 4.4 times and 4.5 times than that of pure BiOCl, respectively. Overall, the BiOCl/Ag₃PO₄ composites not only show highly enhanced visible light photocatalytic activity but also exhibit highly improved UV photocatalytic activity, which could find enormous potential application in addressing environmental protection issues utilizing solar energy effectively.     

One step synthesis of Ag/Ag3PO4/BiPO4 double-heterostructured nanocomposites with enhanced visible-light photocatalytic activity and stability

Heterogeneous Ag/Ag₃PO₄/BiPO₄ photocatalyst was synthesized by a one-step low temperature chemical bath method and exhibited better photocatalytic activity and better stability than those of individual Ag₃PO₄ or BiPO₄ nanoparticles for photodegradation of organic compounds (Rhodamine B) in the absence of electron accepters under visible light (λ>420 nm). The enhanced photocatalytic performance is mainly ascribed to the strong visible-light absorption originating from high efficient separations of photogenerated electron–hole pairs through Ag₃PO₄/BiPO₄ and Ag/Ag₃PO₄ heterostructures.     

Synthesis of novel Cd2P2O7/Ag3PO4 photocatalyst with enhanced visible-light photocatalytic performance and the enhancement mechanism

Novel Cd₂P₂O₇/Ag₃PO₄ photocatalysts containing different mass fractions of Cd₂P₂O₇ were synthesized by a hydrothermal method. The photocatalysts were characterized by X-ray diffractometry, transmission electron microscopy, X-ray photoelectron spectroscopy, Electron spin resonance (ESR), Fourier transform infrared spectrometry, ultraviolet–visible absorption spectroscopy and photoluminescence spectroscopy. Photocatalytic activity was decided by the effective separation and low recombination rate of photogenerated electron-hole pairs. During the experiments, the Cd₂P₂O₇/Ag₃PO₄ composites possessed fierce electron- hole separation capacity. In particular, the 1 wt% Cd₂P₂O₇/Ag₃PO₄ catalyst displayed higher photocatalytic performance than pure Ag₃PO₄ under visible-light irradiation (λ>420 nm). The ESR spectrum showed the main active species during the methyl orange degradation were ·OH and ·O₂⁻.     

Facile synthesis of Ag3PO4 with the assistance of N,N-dimethylformamid and urea for high performance photocatalysis

Ag₃PO₄ was synthesized with the assistance of N, N-dimethylformamid (DMF) and urea for high performance photocatalysis. The photocatalytic activity of the as-synthesized samples was evaluated by photodegrading rhodamine B (Rh B) under visible light irradiation. As a result, the optimal Ag₃PO₄ synthesized with the assistance of DMF and urea exhibited enhanced photocatalytic activity for Rh B degradation under visible light irradiation. DMF and urea play vital roles in improving the photocatalytic activity of Ag₃PO₄. This study could provide a new perspective for the controllable synthesis of Ag₃PO₄.     

Photocatalytic activity of Ag3PO4 and some of its composites under non-filtered and UV-filtered solar-like radiation

Silver phosphate is a promising photocatalyst since its energy band gap is situated in the visible range (E_g≈2.4 eV), thus this material is a potential candidate for replacing titania which is photoactive only under UV. However, Ag₃PO₄ suffers of photocorrosion and therefore composites should be prepared to limit this detrimental effect. In this work, pure Ag₃PO₄ and its composites with AgI, TiO₂, and hydroxyapatite were prepared by using various methods. The photoactivity of the materials was evaluated by their ability to decolorize methylene blue and to mineralize phenol under non-filtered and UV-filtered artificial solar-like radiation. The use of UV cut-off filter enhanced the photocatalytic activity of pure silver phosphate by limiting the photocorrosion of silver(I) into Ag°. For composites with AgI and TiO₂, despite their lower photoactivity compared to pure Ag₃PO₄, the efficiency in mineralization of phenol after repeated run is stabilized by using UV cut-off filter. On the other hand, the photocatalytic efficiency of Ag₃PO₄ composites containing hydroxyapatite remained low mainly due to high absorption properties of hydroxyapatite. The photoactive samples showed excellent photoinduced antimicrobial properties where Gram-negative E. coli was more susceptible to photocatalytic deactivation than Gram-positive S. aureus (MRSA).     

Hydrothermal synthesis and characterization of Lanthanum-doped NaTaO3 with high photocatalytic activity

Lanthanum-doped NaTaO₃ (NaTaO₃:La) nanocrystals have been synthesized by a hydrothermal method. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microcopy (TEM), inductive coupled plasma atomic absorption spectrometric analysis, volumetric adsorption method (BET) and UV–vis spectroscopy were used to characterize the samples. The NaTaO₃:La nanocubes show a higher photocatalytic activity than that of the pure NaTaO₃ in the degradation of the safranine T dye under UV irradiation. The highest photocatalytic activity was achieved when 2 mol% lanthanum was doped.     

Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO₂ nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO₂ nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO₂ nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO₂ nanotube arrays was 51%, much higher than that of pure TiO₂ nanotube arrays. Ag/TiO₂ nanotube arrays exhibited higher photocatalytic activities than the pure TiO₂ nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO₂ nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO₂ nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.     

Selective photocatalytic degradation of azodyes in NiO/Ag3VO4 suspension

BACKGROUND: This work deals with the development of an active heterogeneous catalyst for selective organic synthesis under both visible light and UV irradiation to utilize efficiently solar light. Very few studies have been reported on the selective photooxidation performance of multimetal oxide materials under visible light irradiation. The photocatalytic degradation of azodyes was investigated systematically in aqueous NiO/Ag₃VO₄ dispersion under visible light irradiation. RESULTS: The catalyst NiO/Ag₃VO₄ showed high activity and selectivity for the photodegradation of the nonbiodegradable azodyes acid red B, reactive brilliant red X‐3B, and acid orange 7. From total organic carbon (TOC), Fourier transform infrared spectroscopy (FTIR), and gas chromatography/mass spectroscopy analyses, the tested azodyes were selectively oxidized into aromatic and aliphatic acids without any decrease of TOC. The high photooxidation selectivity also applied to UV light irradiation. Electron spin resonance and radical scavenger studies suggest that the anionic superoxide radical O₂^?? was the predominant active species in the photocatalytic reaction. CONCLUSION: The selectivity of NiO/Ag₃VO₄ for the oxidation of azodyes was not affected by the energy of light (UV and visible light). This approach allows effective controlled oxidation but avoids undesirable mineralization into CO₂ and H₂O. Copyright © 2010 Society of Chemical Industry     

Ag3PO4 quantum dots loaded on the surface of leaf-like InVO4/BiVO4 heterojunction with enhanced photocatalytic activity

Leaf-like InVO₄/BiVO₄ nanoarchitectures with scale of 2 μm–5 μm were prepared by a facile hydrothermal method. Ag₃PO₄ quantum dots (QDs) were then deposited onto the surface of leaf-like InVO₄/BiVO₄ crystals via a simple deposition–precipitation technique. The photocatalytic tests displayed that the Ag₃PO₄/InVO₄/BiVO₄ nanocomposite possesses a much higher rate for degradation of rhodamine B (Rh B) than the sum of BiVO₄, InVO₄, Ag₃PO₄, Ag₃PO₄/InVO₄, Ag₃PO₄/BiVO₄ or InVO₄/BiVO₄ under visible light irradiation. The observed improvement in photocatalytic performance is associated with the extended absorption in the visible light region resulting from the Ag₃PO₄ QD loading, the high specific surface area, and the effective separation of photogenerated carriers at the Ag₃PO₄/InVO₄/BiVO₄ interfaces.     

Increasing the photocatalytic and fungicide activities of Ag3PO4 microcrystals under visible-light irradiation

The present study reports for the first time the performance of silver phosphate (Ag₃PO₄) microcrystals as photocatalyst (degradation of Rodamine B-RhB) and antifungal agent (against Candida albicans–C. albicans) under visible-light irradiation (455 nm). Ag₃PO₄ microcrystals were synthesized by a simple co-precipitation (CP) method at room temperature. The structural and electronic properties of the as-synthetized Ag₃PO₄ have been investigated before and after 4 cycles of RhB degradation under visible light using X-ray diffraction (XRD), micro-Raman spectroscopy, UV–Vis spectrophotometer and field emission scanning electron microscopy (FE-SEM) images. The antifungal activity was analyzed in planktonic cells and 48h-biofilm of C. albicans by colony forming units (CFU) counting, confocal laser and FE-SE microscopies. Statistical analysis was carried out using SPSS software. Morphological and structural modifications of Ag₃PO₄ were observed upon recycling. After 4 recycles, the material maintained its photodegradation property; an eightfold increase in the efficiency of Ag₃PO₄ was observed in planktonic cells and a two fold increase in biofilm when irradiated under visible light. Thus, higher antifungal effectiveness against C. albicans was obtained when associated with visible-light irradiation.     

Preparation, characterization and photocatalytic activity of N-doped NaTaO3 nanocubes

The N-doped NaTaO₃ catalysts with cubic morphology had been successfully synthesized by one-step hydrothermal method, using Ta₂O₅ and NH₃·H₂O as the raw materials for the first time. The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectra. The results showed that the synthesis parameters such as reaction temperature and reaction time played important roles in the formation of N-doped NaTaO₃ nanocubes. As observed by SEM images, when the reaction time reached 12 h, most of the products exhibited the square morphology with the size of 200-500 nm, which can be easily removed by filtration after photocatalytic reaction. The photocatalytic activity of N-doped NaTaO₃ was tested by Methylene Blue degradation process under ultraviolet and visible light irradiation, respectively. The results showed that both under the ultraviolet and visible light irradiation, N-doped NaTaO₃ displayed much higher photocatalytic activity than that of pure NaTaO₃. In addition, NaTaO_3-xN_x composites exhibited excellent stability in the visible-light photocatalytic process.     

Construction of g-C3N4 nanotube/Ag3PO4 S-scheme heterojunction for enhanced photocatalytic oxygen generation

Heterojunction engineering is considered as a hopeful approach to ameliorate the separation of photogenerated carriers of photocatalysts, realizing efficient water-splitting performance. In this study, an organic-inorganic S-scheme of a one-dimensional g-C₃N₄ nanotube (TCN)/Ag₃PO₄ photocatalytic system with high photocatalytic water oxidation activity was designed by coupling g-C₃N₄ nanotubes over Ag₃PO₄ particles through a chemical coprecipitation method. The TCN/Ag₃PO₄ heterojunction demonstrated excellent photocatalytic O₂ production with an O₂ evolution rate of up to 370.2 μmol·L^?1·h^?1. X-ray photoelectron spectroscopy analysis showed that electron migration between TCN and Ag₃PO₄ led to the formation of an internal electric field pointing from TCN to Ag₃PO₄, which drove the S-scheme charge transfer mode between TCN and Ag₃PO₄. Accordingly, the TCN/Ag₃PO₄ heterojunction possessed fast charge separation and high redox ability, leading to high photoactivity and photostability. This research provides a new strategy for fabricating highly efficient inorganic-organic S-scheme photocatalysts for O₂ production.     

Dual Z-scheme heterojunction g-C3N4/Ag3PO4/AgBr photocatalyst with enhanced visible-light photocatalytic activity

Recently, there has been a significant interest in developing high-performance photocatalysts for removing organic pollutants from water environment. Herein, a ternary graphitic C₃N₄ (g-C₃N₄)/Ag₃PO₄/AgBr composite photocatalyst is synthesized using an in-situ precipitation-anion-exchange process and characterized by several spectroscopic and microscopic techniques. During the photocatalytic reaction, X-ray photoelectron spectroscopy clearly illustrated the formation of metallic Ag on the g-C₃N₄/Ag₃PO₄/AgBr composite surface. The ternary composite photocatalyst demonstrated an increased photoactivity under visible light (>420 nm), achieving a complete decolorization of methyl orange (MO) in 5 min. The ternary g-C₃N₄/Ag₃PO₄/AgBr hybrid was also applied to the 2-chlorophenol degradation under visible light, further confirming its excellent photocatalytic activity. In addition, quenching experiments revealed that holes (h⁺) and O₂^?– were the major attack species in the decolorization of MO. The enhanced photoactivity of g-C₃N₄/Ag₃PO₄/AgBr results from the efficient transfer/separation of photoinduced charges with the dual Z-scheme pathway and the charge recombination sites on the formed Ag particles.     

NiTiO3/Ag3PO4 composites with improved photocatalytic activity under visible-light irradiation

A series of NiTiO₃/Ag₃PO₄ composites were prepared by a simple ion-exchange deposition method. The composition and morphology of the samples were determined by XRD, EDS and SEM. UV–vis DRS was used to characterize their optical absorption properties. The loading of NiTiO₃ could promote the efficient separation of photoinduced electron-hole pairs and enhance the charge carrier transport to improve the photocatalytic activity. The APO-5 composite exhibited the best photocatalytic activity for the degradation of methyl violet (MV). Kinetics studies indicated that the APO-5 composite showed an apparent rate constant of 0.115 min⁻¹, which was 2.61 times that of pure Ag₃PO₄.     

Ternary Ag@SrTiO3@CNT plasmonic nanocomposites for the efficient photodegradation of organic dyes under the visible light irradiation

In this research, carbon nanotube (CNT)-modified plasmonic silver-strontium titanate (Ag@ SrTiO₃) nanocomposites for the degradation of the organic dye were prepared by the sol-gel method. The characterization of all products was carried out using the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption test (BET), field emission-scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV–visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, electrochemical impedance spectroscopy (EIS), and transient photocurrent (TPC) studies. It was found that the incorporation of Ag in and introducing CNT into the SrTiO₃ nanoparticles reduced the crystallite size to 21 nm and the band gap energy to 2.7 eV. The Reduced PL peak intensity, increased photocurrent value, and reduced charge transfer resistance approved that the Ag@SrTiO₃@CNT nanocomposite had a greater charge transfer efficiency than other samples. The optimal dosage of the photocatalyst, for the complete degradation of 5 ppm of the methylene blue (MB) solution after 30 min of the visible light irradiation, was decided as 0.5 g/L. Besides, in the experimental environment, the Ag@SrTiO₃@CNT sample illustrated the most significant photocatalytic performance of the degradation of methyl orange (MO) and Rhodamine B (RhB) dyes. The detailed mechanism and kinetics of the degradation procedure were clarified. Finally, the prepared system displayed increased stability and reusability in the entire cyclic degradation experiment.