Synthesis and characterization of g-C3N4/BiFeO3 composites with an enhanced visible light photocatalytic activity

The novel visible light-induced g-C₃N₄/BiFeO₃ composites were successfully synthesized by introducing BiFeO₃ into polymeric g-C₃N₄. The structures and optical properties of composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), field-emission transmission electron microscope (TEM), UV–vis diffuse reflection spectroscopy (DRS), respectively. For the degradation of Rhodamine B (RhB), the g-C₃N₄/BiFeO₃ composites exhibited significantly higher visible light photocatalytic activity than that of a single semiconductor. The optimal percentage of doped g-C₃N₄ was 50%. Both photooxidation and photoreduction processes follow first order kinetics. In addition, the stability of the prepared photocatalyst in the photocatalytic process was also investigated. The enhanced photocatalytic performance could be due to the high separation efficiency of the photogenerated electron–holes pairs. The possible photocatalytic mechanism of g-C₃N₄/BiFeO₃ was proposed to guide the further improvement of their photocatalytic activity.     

g-C3N4/Ag3PO4 composites with synergistic effect for increased photocatalytic activity under the visible light irradiation

The g-C₃N₄ was synthesized by a hydrothermal method and the g-C₃N₄/Ag₃PO₄ composites were prepared by a ordinary precipitation method. Microstructures, morphologies and optical properties of the as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the Ag₃PO₄ nanoparticles were dispersed on the surface of the flake-like g-C₃N₄, and the heterojunction was formed on the interface. The g-C₃N₄/Ag₃PO₄ (2 wt%) photocatalyst presented the highest photocatalytic activity for organic dye methylene blue (MB) degradation, and its photocurrent intensity was approximately 2 times than that of the pure Ag₃PO₄. The g-C₃N₄/Ag₃PO₄ (2 wt%) photocatalyst also exhibited photocatalytic performance in the decomposition of colorless antibiotic ciprofloxacin (CIP). The capture experiment confirmed that holes acted as the main active species during the photocatalytic reaction.     

Enhanced photo-induced charge separation and solar-driven photocatalytic activity of g-C3N4 decorated by SO42−

SO₄²⁻ decorated g-C₃N₄ with enhanced photocatalytic performance was prepared by a facile pore impregnating method using (NH₄)₂S₂O₈ solution. The photocatalysts were characterized by the Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and surface photovoltage (SPV) spectroscopy, respectively. The separation efficiency of photo-generated charge was investigated using benzoquinone as scavenger. The results demonstrate that sulfating of g-C₃N₄ increases the adsorption of rhodamine B on g-C₃N₄, the hydroxyl content and the separation efficiency of photo-generated charge. The photocatalytic activity of SO₄²⁻/g-C₃N₄ for decolorization of rhodamine B and methyl orange (MO) aqueous solution was evaluated. The result shows that loading of 6.0 wt% SO₄²⁻ results in the best photocatalytic activity under simulated solar irradiation and SO₄²⁻ play an important role in boosting the photocatalytic activity.     

Fabrication of Bi2MoO6 nanoplates hybridized with g-C3N4 nanosheets as highly efficient visible light responsive heterojunction photocatalysts for Rhodamine B degradation

The Bi₂MoO₆/g-C₃N₄ heterojunction photocatalysts have been successfully fabricated using a simple liquid chemisorptions and thermal post-treatment. These nanostructured Bi₂MoO₆/g-C₃N₄ composites were extensively characterized by X-ray diffraction(XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR),UV–vis diffuse reflectance spectra (UV–vis DRS) and Photoluminescence (PL). The photocatalytic results show that 20 wt% Bi₂MoO₆/g-C₃N₄ sample exhibits efficient visible light activity and excellent photo-stability. The kinetic constant of RhB degradation over 20 wt% Bi₂MoO₆/g-C₃N₄ is about 5 and 2.5 times higher than that over pure Bi₂MoO₆ and g-C₃N₄ nanosheets, respectively. The enhanced photocatalytic performance is attributed to the construction of heterogeneous interface to promote photo-induced charge carrier pairs separation.     

Significant improvement of photocatalytic activity of porous graphitic-carbon nitride/bismuth oxybromide microspheres synthesized in an ionic liquid by microwave-assisted processing

Graphitic-carbon nitride/bismuth oxybromide (g-C₃N₄/BiOBr) porous microspheres have been successfully synthesized by a one-pot ethylene glycol (EG) assisted microwave process in the presence of 1-hexadecyl-3-methylimidazolium bromine ([C₁₆mim]Br). The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and UV–vis diffuse reflectance spectroscopy (DRS). During the reaction process, the ionic liquid acts not only as solvent and Br source but also as a template for fabrication of g-C₃N₄/BiOBr porous microspheres. In addition, the photocatalytic activity of the g-C₃N₄/BiOBr is evaluated by degrading Rhodamine B (RhB) and ciprofloxacin (CIP) under visible-light irradiation. It is found that 12.75 wt% g-C₃N₄/BiOBr microspheres exhibit higher photocatalytic activity than that of the as-prepared BiOBr. A possible photocatalytic mechanism based on the relative band positions of g-C₃N₄/BiOBr has been proposed.     

Highly efficient visible-light driven AgBr/Ag3PO4 hybrid photocatalysts with enhanced photocatalytic activity

Highly efficient visible-light-driven AgBr/Ag₃PO₄ hybrid photocatalysts with different mole ratios of AgBr were prepared via an in-situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgBr/Ag₃PO₄ photocatalysts displayed the higher photocatalytic activity than pure Ag₃PO₄ and AgBr for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgBr/Ag₃PO₄ with 60% of AgBr exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgBr/Ag₃PO₄ readily transformed to be Ag@AgBr/Ag₃PO₄ system while the photocatalytic activity of AgBr/Ag₃PO₄ remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h⁺ and O₂^∙− play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgBr/Ag₃PO₄ hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag₃PO₄, Ag and AgBr, in which Ag nanoparticles act as the charge separation center.     

Effect of morphology on the photocatalytic activity of g-C3N4 photocatalysts under visible-light irradiation

Graphite-like carbon nitride (g-C₃N₄) photocatalysts with different morphologies have been synthesized using melamine as a precursor using a template-free wet chemical method. The as-prepared g-C₃N₄ nanorods, g-C₃N₄ microcones and porous g-C₃N₄ quadruple prisms were characterized by XRD, FESEM, FT-IR and UV–vis absorption spectrophotometer. These nanostructured g-C₃N₄ photocatalysts show better photocatalytic activity than bulk g-C₃N₄ under visible light irradiation in view of degrading Rhodamine B (RhB). The porous g-C₃N₄ quadruple prisms show the highest photocatalytic efficiency. We deduce that the surface area of the catalysts and their adsorption ability of target molecules play important roles in improving the photocatalytic activity of the g-C₃N₄ photocatalysts.     

Fabrication and enhanced performance of calcium metasilicate-stabilized silver-promoted anatase photocatalysts

A range of calcium metasilicate–silver promoted-anatase (Ag–TiO₂–CaSiO₃) photocatalysts was obtained by photoreduction and physisorption methods. The calcium metasilicate (CaSiO₃) materials were prepared by chemical precipitation technology. The structure and morphology of photocatalysts were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) characterization methods. The results show that the anatase (TiO₂) and silver promoted-anatase (Ag–TiO₂) particles were evenly distributed on the surface of calcium silicate material. After the activity of photocatalysts was evaluated through the degradation rate of methyl orange (MO), the results showed that the 4% Ag–TiO₂/CaSiO₃ products have higher activity during the reaction, and the products showed excellent reusability after that these were repeated five times. The sample of Ag–TiO₂/CaSiO₃ exhibits activity of MO degradation under visible light (λ >400 nm) because of the active sites of Ag nanoparticles. The novel composite photocatalysts might have potential applications in the treatment of environmental pollution.     

Directly assembled quantum dots on one dimension ordered TiO2 nanostructure in aqueous solution for improving photocatalytic activity

One dimension (1D) ordered titanium dioxide (TiO2) nanostructured photocatalysts sensitized by quantum dots (QDs) are fabricated. Their morphologies, crystal structures and photocatalytic properties are characterized by scanning elec-tron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectroscopy, respectively. Compared with the original TiO2 nanostructure, the nanostructured TiO2 sensitized by QDs exhibits a good photocatalytic activity for the degradation of methyl orange (MO). The QDs with core-shell structure can reduce the photocatalytic ability due to the higher potential barrier of carrier transport in ZnS shell layer. The results indicate that the proposed photocatalyst shows promising potential for the application in organic dye degradation.     

Enhanced properties for visible-light-driven photocatalysis of Ag nanoparticle modified Bi2MoO6 nanoplates

The visible light driven Bi₂MoO₆ photocatalyst doped with different contents of Ag nanoparticles was successfully synthesized by a combination of hydrothermal and sonochemical methods. The as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM and TEM) and UV–visible spectroscopy to investigate crystalline structure, morphology, composition and photocatalytic properties. XRD patterns and TEM images of the samples revealed pure phase orthorhombic Bi₂MoO₆ nanoplates without any detection of Ag dopant due to its low concentration and very tiny particle size. TEM images showed that Ag nanoparticles with the size of 10–15 nm were dispersed randomly on the surface of Bi₂MoO₆. The XPS analysis of Ag/Bi₂MoO₆ nanocomposites revealed the presence of additional metallic Ag. Photocatalytic activities of the Ag/Bi₂MoO₆ nanocomposites were evaluated by determining the degradation of rhodamine B (RhB) under visible light radiation. In this research, the 10 wt% Ag/Bi₂MoO₆ nanocomposites showed the best photocatalytic activity. The results suggest that the dispersion of Ag nanoparticles on the surface of Bi₂MoO₆ significantly enhances its photocatalytic activity.     

Hybridized Nanowires and Cubes: A Novel Architecture of a Heterojunctioned TiO2/SrTiO3 Thin Film for Efficient Water Splitting

A unique morphology of SrTiO₃ nanocubes precipitated on TiO₂ nanowires is successfully synthesized in the form of a thin‐film heterojunctioned TiO₂/SrTiO₃ photocatalyst using facile hydrothermal techniques. The formation mechanisms of the synthesized photocatalysts are meticulously studied and described. Growth of SrTiO₃ single crystal nanocubes (≈50 nm in width) on anatase polycrystalline nanowires follows an in situ dissolution‐precipitation pathway. This is consonant with the classic LaMer model. By analyzing the results of field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X‐ray diffraction (XRD), energy dispersive X‐ray (EDX) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and UV‐vis spectrophotometry, a comprehensive structural and morphological characterization of the photocatalysts is established. FESEM images reveal that the anatase film comprises mainly of nanowires bristles while the tausonite film is primarily made up of nanocube aggregations. In comparison to the respective pristine semiconductor photocatalysts, the heterostructured photocatalyst demonstrates the highest efficiency in photocatalytic splitting of water to produce H₂, 4.9 times that of TiO₂ and 2.1 times that of SrTiO₃. The enhanced photocatalytic efficiency is largely attributed to the efficient separation of photogenerated charges at heterojunctions of the two dissimilar semiconductors, as well as a negative redox potential shift in the Fermi level.     

Visible light assisted photocatalytic activity of TiO2–metal vanadate (M=Sr,Ag and Cd) nanocomposites

TiO₂–metal vanadate nanocomposites (TiO₂–MV) were synthesized by the precipitation method and successfully characterized using UV–visible diffuse reflectance spectroscopy (UV–vis-DRS), powder X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) techniques. The photocatalytic activity of TiO₂–MV was investigated for the degradation of fast green (FG) dye under visible light irradiation. The photocatalytic activity of TiO₂–silver vanadate [TiO₂–Ag₃VO₄] was found to be much higher than that of TiO₂–cadmium vanadate [TiO₂–CdV₂O₆], TiO₂–strontium vanadate [TiO₂–Sr₃(VO₄)₂] and TiO₂. The effect of operational parameters such as pH, photocatalyst concentration and initial dye concentration on the photodegradation of FG was examined in detail. The mineralization of FG was confirmed by chemical oxygen demand (COD) and total organic carbon (TOC) measurements. Moreover, TiO₂–Ag₃VO₄ was found to be a reusable photocatalyst.     

Simultaneously Tuning Band Structure and Oxygen Reduction Pathway toward High-Efficient Photocatalytic Hydrogen Peroxide Production Using Cyano-Rich Graphitic Carbon Nitride

The demands for green production of hydrogen peroxide have triggered extensive studies in the photocatalytic synthesis, but most photocatalysts suffer from rapid charge recombination and poor 2e⁻ oxygen reduction reaction (ORR) selectivity. Here, a novel composite photocatalyst of cyano-rich graphitic carbon nitride g-C₃N₄ is fabricated in a facile manner by sodium chloride-assisted calcination on dicyandiamide. The obtained photocatalysts exhibit superior activity (7.01 mm  h⁻¹ under λ  ≥  420 nm, 16.05 mm  h⁻¹ under simulated sun conditions) for H₂O₂ production and 93% selectivity for 2e⁻ ORR, much higher than that of the state-of-the-art photocatalyst. The porous g-C₃N₄ with Na dopants and cyano groups simultaneously optimize two limiting steps of the photocatalytic 2e⁻ ORR: photoactivity, and selectivity. The cyano groups can adjust the band structure of g-C₃N₄ to achieve high activity. They also serve as oxygen adsorption sites, in which local charge polarization facilitates O₂ adsorption and protonation. With the aid of Na⁺, the O₂ is reduced to produce more superoxide radicals as the intermediate products for H₂O₂ synthesis. This work provides a facile approach to simultaneously tune photocatalytic activity and 2e⁻ ORR selectivity for boosting H₂O₂ production, and then paves the way for the practical application of g-C₃N₄ in environmental remediation and energy supply.     

Fabrication of heterojunction SnO2/BiVO4 composites having enhanced visible light photocatalystic activity

SnO₂/BiVO₄ heterojunction composite photocatalysts with various mole ratios have been prepared via a simple hydrothermal method. The structure, composition and optical properties of the SnO₂/BiVO₄ composites were determined by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface analysis, X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). Photocatalytic activities of the composites were evaluated by studying the degradation of methylene blue (MB) solutions under simulated visible light irradiation (500 W halogen tungsten lamp). The 3:7 mol ratio SnO₂/BiVO₄ composite exhibited the highest photocatalytic performance, leading to 72% decompositon of MB within 120 min of irradiation.     

Synthesis of mesoporous titania–graphite composite templated by hypocrellins for visible-light photocatalytic degradation of acetaldehyde

A photoactive compound extracted from a fungus (Hypocrella bambuase), named hypocrellins, was used as template to synthesize thermally stable mesoporous materials. The synthesized mesoporous titania samples were characterized using a combination of various physicochemical techniques, such as N₂ adsorption/desorption measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FT-IR). The results of physicochemical characterizations showed that the as-synthesized sample was a composite of highly crystalline mesoporous anatase titania and graphitic carbon (gc–MTiO₂), which implies the dual function of hypocrellins as template and “dopant”. The in situ doped graphitic carbon significantly increased the visible-light absorbance of TiO₂. The gc–MTiO₂ exhibited efficient photocatalytic activity under visible-light for photodegradation of acetaldehyde, a common indoor air pollutant. The photophysics and electron dynamics in this photocatalytic process were studied by time-resolved FT-IR spectra, in particular on the nano- to milli-second time scale. It is observed that electrons were injected into the conduction band of gc–MTiO₂ and they were decayed to deep traps caused by graphitic carbon. The reported strategies could open up new uses for mesoporous titania self-doped with carbon in applications such as solar cells, photocatalysts, photoelectrical devices, and photo-induced sensors.     

Visible light photocatalytic activity of reduced graphene oxide synergistically enhanced by successive inclusion of γ-Fe2O3, TiO2, and Ag nanoparticles

Novel magnetic nanocomposites are synthesized by loading reduced graphene oxide (r-GO) with three brands of nanoparticles consisting of titanium dioxide (TiO₂), gamma-iron(III) oxide (γ-Fe₂O₃), and silver (Ag) with varying amounts. The resulting Ag/TiO₂/γ-Fe₂O₃@r-GO demonstrates synergistically enhanced visible light photocatalytic activity, on degradation of wastewater׳s toxic crystal violet (CV). Specifically, it exhibits higher photoactivity than those of neat graphene oxide (GO), TiO₂@GO, γ-Fe₂O₃@GO, and TiO₂/γ-Fe₂O₃@GO, possibly because of effective separation of photogenerated carriers via strongly coupled Ag/γ-Fe₂O₃@r-GO cocatalyst and the enrichment of organic molecules on the graphene nanosheets. A higher photocatalytic efficiency is observed when 11.5 wt% Ag nanoparticles are incorporated in TiO₂/γ-Fe₂O₃@GO. After 3 successive cycles, the latter nanocomposite maintains 97% removal efficiency with excellent stability and easy recovery. Considering its facile preparation and high photocatalytic activity, it is hoped that this photocatalyst will find its application in various fields such as air purification and wastewater treatment. The structure and properties of Ag/TiO₂/γ-Fe₂O₃@r-GO are characterized by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), ultraviolet–visible spectrometry (UV–vis) and Raman spectroscopy techniques.     

Dual Functions of CO2 Molecular Activation and 4f Levels as Electron Transport Bridge in Dysprosium Single Atom Composite Photocatalysts with Enhanced Visible-Light Photoactivities

The effect of rare earth (RE) single atoms on photocatalytic activity is very complex due to its special electronic configuration, which leads to few reports on the RE single atoms. Here, Dy³⁺ single atom composite photocatalysts are successfully constructed based on both the special role of Dy³⁺ and the special advantages of CdS/g-C₃N₄ heterojunction in the field of photocatalysis. The results show that an efficient way of electron transfer is provided to promote charge separation, and the dual functions of CO₂ molecular activation of rare-earth single atom and 4f levels as electron transport bridge are fully exploited. It is exciting that under visible-light irradiation, the catalytic performance of CdS:Dy³⁺/g-C₃N₄ is ≈ 6.9 times higher than that of pure g-C₃N₄. The catalytic performance of CdS:Dy³⁺ and CdS:Dy³⁺/g-C₃N₄ are ≈ 7 and ≈ 13.7 times higher than those of pure CdS, respectively. Besides, not all RE ions are suitable for charge transfer bridges, which is not only related to the 4f levels of RE ions but also related to the bandgap structure of CdS and g-C₃N₄. The pattern of combining single-atom catalysis and heterojunction opens up new methods for enhancing photocatalytic activity.     

Synthesis of Pd co-doped nano-TiO2–SO42– and its synergetic effect on the solar photodegradation of Reactive Red 120 dye

Pd co-doped TiO₂–SO₄^2– photocatalyst was synthesized by sol–gel, photodeposition methods and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and BET surface area measurements. Elements present in the catalyst are shown by X-ray photoelectron spectroscopy. X-ray diffraction analysis reveals that the photocatalyst has an anatase structure. Sulfation by sulfuric acid reduces agglomeration, inhibits the phase transformation and enhances the stability of TiO₂. The solar photocatalytic activity of the Pd–TiO₂–SO₄^2– is higher than that of the TiO₂–P25, Pd–TiO_2, bare TiO₂ and TiO₂–SO₄^2– at pH 7 for the mineralization of Reactive Red 120. The modification of palladium shows higher adsorption with synergistic effect and also enhances the separation of photogenerated electron–hole pairs, leading to higher photodegradation efficiency. The effects of operational parameters such as the amount of photocatalyst, initial pH on photo mineralization have been analyzed. A dual mechanism of degradation by Pd–TiO₂–SO₄^2– is proposed to explain its higher activity in solar light. The mineralization of Reactive Red 120 has also been confirmed by CV and COD measurements. The catalyst is found to be stable and reusable. Based on the degradation intermediates identified by GC–MS analysis, a reaction pathway is proposed.     

Sol–gel-synthesized mesoporous-assembled TiO2–ZrO2 mixed oxide nanocrystals and their photocatalytic sensitized H2 production activity under visible light irradiation

The purpose of this work was to investigate, in the first study of its kind, hydrogen production by photocatalytic water splitting under visible light irradiation using Eosin Y-sensitized mesoporous-assembled TiO₂–ZrO₂ mixed oxide nanocrystal photocatalysts. The mesoporous-assembled TiO₂–ZrO₂ mixed oxide nanocrystals, with various TiO₂-to-ZrO₂ molar ratios, were synthesized by a sol–gel method with the aid of a structure-directing surfactant. The synthesized nanocrystals were characterized by thermogravimetric and derivative thermogravimetric analyzer, N₂ adsorption–desorption, X-ray diffraction, UV–visible spectroscopy, scanning electron microscope–energy-dispersive X-ray analyzer, and transmission electron microscope analyses. Parameters affecting the photocatalytic activity, including calcination conditions and phase composition, were mainly discussed. Experimental results showed that the incorporation of ZrO₂ with suitable contents could preserve the mesoporous-assembled structure of TiO₂ at high calcination temperatures and enhance its thermal stability significantly. Results of the photocatalytic-sensitized hydrogen production revealed that the TiO₂–ZrO₂ mixed oxide photocatalyst, with a TiO₂-to-ZrO₂ molar ratio of 95:5, calcined at 800 °C for 4 h, provided maximum photocatalytic hydrogen production activity. The optimized TiO₂–ZrO₂ mixed oxide photocatalyst can be considered as a potential photocatalyst for hydrogen production under solar light irradiation.     

Highly efficient photocatalytic treatment of mixed dyes wastewater via visible-light-driven AgI–Ag3PO4/MWCNTs

A high-performance photocatalyst of AgI–Ag₃PO₄/multi-walled carbon nanotubes (MWCNTs) was fabricated by chemical precipitation method using KI, K₂HPO₄ and AgNO₃ in the presence of MWCNTs. Its structure and physical properties were characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), UV–vis absorption spectra, X-ray photo-electron spectroscopy (XPS), photoluminescence spectra (PL) and photocurrent techniques. SEM, TEM and EDS analyses verified that AgI–Ag₃PO₄ is successfully loaded on MWCNTs. AgI–Ag₃PO₄/MWCNTs possess the absorption edge of red shift and small band gap energy, and could absorb more photons in the visible region. PL and photocurrent analyses illustrated that AgI–Ag₃PO₄/MWCNTs have the lowest emission peak intensity and the highest photoelectric current, compared with Ag₃PO₄, AgI and AgI–Ag₃PO₄. By using the photocatalytic degradation of mixed dyes wastewater of Orange II and ponceau 4R as a model reaction, the photocatalytic efficiencies of Ag₃PO₄, AgI, AgI–Ag₃PO₄ and AgI–Ag₃PO₄/MWCNTs were evaluated. The reaction results showed that AgI–Ag₃PO₄/MWCNTs have strong photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared AgI–Ag₃PO₄/MWCNTs could act as a high-performance catalyst for the photocatalytic degradation of mixed dyes wastewater and also suggested the promising applications.