Synthesis of ternary rGO–ZnO–Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanocomposites and their application for visible light photocatalytic degradation of dyes

The rGO–ZnO–Fe₃O₄ nanocomposites were synthesized by a simple, economical and environmentally benign solvothermal method. The morphology, structure and photocatalytic activity of rGO–ZnO–Fe₃O₄ nanocomposites were characterized, and the effects of the preparation conditions were analyzed. The 25 mg of rGO–ZnO–Fe₃O₄ nanocomposites performed efficient photocatalytic activity for the degradation of 25 mL of 4.79 mg/L Rhodamine B under both ultraviolet and visible light irradiation. The nanocomposites could be easily retrieved from the wastewater by extra magnetic field due to the presence of magnetic Fe₃O₄ nanoparticles. After the degradation experiment was carried out five times, the degradation ratio is still close to 90% after irradiation after 5 cyclic, indicating that the rGO–ZnO–Fe₃O₄ nanocomposites have high stability for reuse. Therefore, the prepared rGO–ZnO–Fe₃O₄ nanocomposites may be a promising potential material for wastewater treatment.     

The carboxylate magnetic – Zinc based metal-organic framework heterojunction: Fe3O4-COOH@ZIF-8/Ag/Ag3PO4 for plasmon enhanced visible light Z-scheme photocatalysis

In this work, magnetic nanoparticles (MNPs) grafted with carboxylic acid (Fe₃O₄-COOH MNPs) were successfully prepared from incorporation of glutaric anhydride as a functional group on the surface of the ferrite NPs. The MNP was used as a template to induce the growth of ZIF-8 metal–organic framework (MOF) on its surface. The Fe₃O₄-COOH@ZIF-8 core-shell was incorporated with silver phosphate (Ag₃PO₄) and Ag nanoparticles (Ag NPs) to develop a visible light active Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst. The materials were characterized using a range of techniques. The photocatalytic activity was investigated systematically by degrading an organo-phosphorus pesticide, diazinon under visible light irradiation. Among synthesized samples, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ heterostructured system exhibited highest photocatalytic activity and improved stability compared to others for the degradation of diazinon under visible light. The superior activity and improved stability of this heterostructured photocatalyst was attributed to the synergistic effects from surface plasmon resonance (SPR) of Ag NPs and sequential energy transfer via Z-scheme mechanism, for effective separation of electron-hole pairs. Radical-trapping experiments demonstrate that holes (h⁺) and O₂⁻ are primary reactive species involved in photocatalytic oxidation process. Moreover, the Fe₃O₄-COOH@ZIF-8/Ag/Ag₃PO₄ photocatalyst did not show any obvious loss of photocatalytic activity during five cycle tests, which indicate that the heterostructured photocatalyst was highly stable and can be used repeatedly. Therefore, the work provides new insights into the design and fabrication of metal-organic frameworks (MOFs) for use as a visible light photocatalyst for degrading organic contaminants.     

A Hierarchical Z‐Scheme CdS–WO3 Photocatalyst with Enhanced CO2 Reduction Activity

The development of an artificial photosynthetic system is a promising strategy to convert solar energy into chemical fuels. Here, a direct Z‐scheme CdS–WO₃ photocatalyst without an electron mediator is fabricated by imitating natural photosynthesis of green plants. Photocatalytic activities of as‐prepared samples are evaluated on the basis of photocatalytic CO₂ reduction to form CH₄ under visible light irradiation. These Z‐scheme‐heterostructured samples show a higher photocatalytic CO₂ reduction than single‐phase photocatalysts. An optimized CdS–WO₃ heterostructure sample exhibits the highest CH₄ production rate of 1.02 μmol h^?1 g^?1 with 5 mol% CdS content, which exceeds the rates observed in single‐phase WO₃ and CdS samples for approximately 100 and ten times under the same reaction condition, respectively. The enhanced photocatalytic activity could be attributed to the formation of a hierarchical direct Z‐scheme CdS–WO₃ photocatalyst, resulting in an efficient spatial separation of photo‐induced electron–hole pairs. Reduction and oxidation catalytic centers are maintained in two different regions to minimize undesirable back reactions of the photocatalytic products. The introduction of CdS can enhance CO₂ molecule adsorption, thereby accelerating photocatalytic CO₂ reduction to CH₄. This study provides novel insights into the design and fabrication of high‐performance artificial Z‐scheme photocatalysts to perform photocatalytic CO₂ reduction.     

Photochemical deposition of platinum on titanium dioxide–tungsten trioxide nanocomposites: an efficient photocatalyst under visible light irradiation

Highly ordered titanium dioxide–tungsten trioxide nanotubular composites (TiO₂–WO₃) were fabricated on titanium sheets by electrochemical anodizing. Platinum nanoparticles have been successfully deposited onto TiO₂–WO₃ nanotubes by UV light photoreduction method. In this work, X-ray diffraction, field emission scanning electron microscope, ultraviolet–visible spectroscopy and energy dispersive X-ray spectrometer methods were adopted to characterize the samples. The degradation of methylene blue (MB) was used as a model reaction to evaluate the photocatalytic activity of the obtained samples. After irradiated under visible light for 60 min, the degradation rate of MB solution on unmodified TiO₂–WO₃ and Pt/TiO₂–WO₃ reached 77 and 93 %, respectively. Under the same condition, no obvious photodegradation of MB was found for bare TiO₂ (T). Kinetic research showed that photodegradation process followed the first-order reaction; the apparent reaction rate constant of Pt/TiO₂–WO₃-1 was 4.56 × 10^?2 min^?1 which is approximately 1.75 times higher than that on the unmodified TiO₂–WO₃. This work provides an insight into designing and synthesizing new TiO₂–WO₃ nanotubes based hybrid materials for effective visible light-activated photocatalysis.     

Synthesis of porous Fe3O4/g-C3N4 nanospheres as highly efficient and recyclable photocatalysts

A facile approach for the preparation of Fe₃O₄/g-C₃N₄ nanospheres with good porous structure has been demonstrated by a hydrothermal method. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet–visible light (UV–vis) absorbance spectra and X-ray photoelectron spectroscopy (XPS). The photocatalytic decomposition of methyl orange (MO) by the as-prepared samples was carried out under visible light irradiation. The reusability and magnetic properties were also investigated. The results revealed that the porous Fe₃O₄/g-C₃N₄ nanospheres showed considerable photocatalytic activity, and exhibited excellent reusability and magnetic properties with almost no change after five runs.     

Synthesis of polyaniline-modified Fe3O4/SiO2/TiO2 composite microspheres and their photocatalytic application

Polyaniline-modified Fe₃O₄/SiO₂/TiO₂ composite microspheres have been successfully synthesized by sol–gel reactions on Fe₃O₄ microspheres followed by the chemical oxidative polymerization of aniline. The synthesized multilayer-structured composites were characterized by TEM, XRD, TGA, UV–vis diffuse reflectance spectra and magnetometer. The photocatalytic activity was evaluated by the photodegradation of methylene blue under visible light. The effect of polyaniline (PANI) amounts on the photocatalytic activity was investigated. The photocatalytic activity results show that the Fe₃O₄/SiO₂/TiO₂ composites with about 2.4 wt.%–4.1 wt.% PANI could show higher photocatalytic efficiency than that of Fe₃O₄/SiO₂/TiO₂. Furthermore, the PANI-Fe₃O₄/SiO₂/TiO₂ photocatalyst could be easily recovered using a magnet.     

Enhanced photocatalytic activity of Fe3O4-WO3-APTES for azo dye removal from aqueous solutions in the presence of visible irradiation

Development of highly active photocatalysts for treatment of dye-laden wastewaters is vital. The photocatalytic removal of azo dye Reactive Black 5 was investigated by Fe₃O₄-WO₃-3-aminopropyltriethoxysilane (APTES) nanoparticles in the presence of visible light. The Fe₃O₄-WO₃-APTES nanoparticles were synthesized via a facile coprecipitation method. The photocatalyst was characterized by XRD, FT-IR, SEM, EDX, VSM, UV–Vis, and pH_PZC techniques. The effects of some operational parameters such as solution pH, nanophotocatalyst dosage, initial RB5 concentration, H₂O₂ concentration, different purging gases, and type of organic compounds on the removal efficiency were studied by the Fe₃O₄-WO₃-APTES nanoparticles as a photocatalyst. Maximum phtocatalytic activity was obtained at pH 3. The photocatalytic removal of RB5 increased with increasing H₂O₂ concentration up to 5?mM. The removal efficiency declined in the presence of different purging gases and all types of organic compounds. First-order rate constant (k_obs) decreased from 0.027 to 0.0022?min^?1 and electrical energy per order (E_Eo) increased from 21.33 to 261.82 (kWh/m³) with increasing RB5 concentration from 10 to 100?mg/L, respectively. The efficiency of LED/Fe₃O₄-WO₃-APTES process for RB5 removal was approximately 89.9%, which was more effective than the LED/Fe₃O₄-WO₃ process (60.72%). Also, photocatalytic activity decreased after five successive cycles.     

Heterostructured Fe3O4/Bi2O2CO3 photocatalyst: Synthesis,characterization and application in recyclable photodegradation of organic dyes under visible light irradiation

Heterostructured Fe₃O₄/Bi₂O₂CO₃ photocatalyst was synthesized by a two-step method. First, Fe₃O₄ nanoparticles with the size of ca. 10 nm were synthesized by chemical method at room temperature and then heterostructured Fe₃O₄/Bi₂O₂CO₃ photocatalyst was synthesized by hydrothermal method at 180 °C for 24 h with the addition of 10 wt% Fe₃O₄ nanoparticles into the precursor suspension of Bi₂O₂CO₃. The pH value of synthesis suspension was adjusted to 4 and 6 with the addition of 2 M NaOH aqueous solution. By controlling the pH of synthesis suspension at 4 and 6, sphere- and flower-like Fe₃O₄/Bi₂O₂CO₃ photocatalysts were obtained, respectively. Both photocatalysts demonstrate superparamagnetic behavior at room temperature. The UV–vis diffuse reflectance spectra of the photocatalysts confirm that all the heterostructured photocatalysts are responsive to visible light. The photocatalytic activity of the heterostructured photocatalysts was evaluated for the degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution over the photocatalysts under visible light irradiation. The heterostructured photocatalysts prepared in this study exhibit highly efficient visible-light-driven photocatalytic activity for the degradation of MB and MO, and they can be easily recovered by applying an external magnetic field.     

High performance magnetically recoverable g-C3N4/Fe3O4/Ag/Ag2SO3 plasmonic photocatalyst for enhanced photocatalytic degradation of water pollutants

The g-C₃N₄/Fe₃O₄/Ag/Ag₂SO₃ nanocomposites have been successfully fabricated by facile refluxing method. The as-obtained products were characterized by XRD, EDX, SEM, TEM, UV–vis DRS, FT–IR, TGA, PL, and VSM techniques. The results suggest that the Ag/Ag₂SO₃ nanoparticles have anchored on the surface of g-C₃N₄/Fe₃O₄ nanocomposite, showing strong absorption in the visible region. The evaluation of photocatalytic activity indicates that for the g-C₃N₄/Fe₃O₄/Ag/Ag₂SO₃ (40%) nanocomposite, the degradation rate constant was 188 × 10^?4 min^?1 for rhodamine B, exceeding those of the g-C₃N₄ (16.0 × 10^?4 min^?1) and g-C₃N₄/Fe₃O₄ (20.2 × 10^?4 min^?1) by factors of 11.7 and 9.3, respectively. The results showed that the nanocomposite prepared by refluxing for 120 min has the superior photocatalytic activity and its activity decreased with rising the calcination temperature. The trapping experiments confirmed that superoxide ion radical was the main active species in the photocatalytic degradation process. Also, it was demonstrated that the magnetic photocatalyst has considerable activity in degradation of one more dye pollutant. Finally, the reusability of the photocatalyst was evaluated by five consecutive catalytic runs. This work may open up new insights into the utilization of magnetically separable nanocomposites and provide new opportunities for facile fabrication of g-C₃N₄-based plasmonic photocatalysts.     

Oxalic acid assisted hydrothermal synthesis and optical absorption property of WO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> nanocomposites

The WO₃/TiO₂ nanocomposites were successfully prepared via a facile oxalic acid assisted hydrothermal process. The oxalic acid played a vital role on the preparation of WO₃/TiO₂ nanocomposites. Notably, it has been observed that the nanocomposites exhibited the wider absorption edge, and the higher photocatalytic activity, compared with pure TiO₂. In addition, the photocatalytic mechanism was proposed, and it elaborated that WO₃/TiO₂ nanocomposite promoted the separation of the photoproduction carriers, and improved photocatalytic activity. The WO₃/TiO₂ nanocomposite may have a potential application as a UV–visible photocatalyst.     

Magnetically recoverable highly efficient visible-light-active g-C3N4/Fe3O4/Ag2WO4/AgBr nanocomposites for photocatalytic degradations of environmental pollutants

Herein, magnetically recoverable g-C₃N₄/Fe₃O₄/Ag₂WO₄/AgBr (gCN/M/AgW/AgBr) nanocomposites, as greatly efficient visible-light-active photocatalysts, were fabricated by successive decoration of Fe₃O₄, Ag₂WO₄, and AgBr over g-C₃N₄ (gCN) and they were characterized by XRD, EDX, SEM, TEM, HRTEM, UV–vis DRS, FT-IR, PL, TG, and VSM analysis. Visible-light-induced photocatalytic performances were studied by degradations of RhB, MB, MO, and fuchsine pollutants. It was confirmed that the nanocomposites are effective in the reduction of e^?/h⁺ recombination through the matched interactions between energy bands of gCN, Fe₃O₄, Ag₂WO₄, and AgBr semiconductors. The highest photocatalytic degradation efficiency was observed for the gCN/M/AgW/AgBr (30%) nanocomposite when it was refluxed for 30?min. Activity of this nanocomposite is almost 21, 41, 94, and 10-folds greater than those of the gCN toward the degradations of RhB, MB, MO, and fuchsine pollutants, respectively. Additionally, a mechanism for the superior photocatalytic performances was proposed using reactive species scavenging experiments and characterization results.     

The enhanced visible light photocatalytic activity of nanosheet-like Bi2WO6 obtained by acid treatment for the degradation of rhodamine B

Bi₂WO₆ samples were fabricated by chemical solution decomposition (CSD) method and nanosheet-like Bi₂WO₆ samples could be obtained by concentrated nitric acid treatment at 70 °C for 20 min. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and UV-vis diffuse reflectance spectra. Photocatalytic activities of the samples were evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. The temperature of acid treatment obviously influenced morphology and the visible light photocatalytic activity of the Bi₂WO₆ samples. The nanosheet-like Bi₂WO₆ photocatalysts obtained by acid treatment exhibited the highest photocatalytic activity under visible light irradiation.     

Interactions of gamma rays with tungsten-doped lead phosphate glasses

Undoped lead phosphate glass of the composition PbO 50 mol%, P₂O₅ 50 mol% together with samples of the same ratio doped with various WO₃ contents were prepared. UV–Visible spectroscopic studies were measured out in the range 200–1100 nm before and after successive gamma irradiation. Infrared and Raman spectroscopic measurements were carried out for the undoped and WO₃-doped samples. All the prepared samples are observed to absorb strongly in the UV region due to the combined contributions of absorption from trace iron impurities and sharing of lead Pb²⁺ ions. The bluish WO₃-doped lead phosphate samples reveal visible absorption bands which are attributed to the existence of pentavalent W⁵⁺ ions. ESR measurements support this assumption. Infrared and Raman spectra indicate the presence of metaphosphate chains as the structural main building units and the possible presence of appreciable pentavalent (W⁵⁺O₃) of W⁵⁺ units together with hexavalent WO₄ units. Gamma irradiation reveal the shielding behaviour of the studied tungsten-doped lead phosphate glasses due to the combined presence of heavy Pb²⁺ ions and tungsten ions.     

Assembly of WO<Subscript>3</Subscript> nanosheets/Bi<Subscript>24</Subscript>O<Subscript>31</Subscript>Br<Subscript>10</Subscript> nanosheets composites with superior photocatalytic activity for degradation of tetracycline hydrochloride

In this work, a high-performance composite photocatalyst composed of WO₃ nanosheets and Bi₂₄O₃₁Br₁₀ nanosheets was successfully synthesized. The photocatalytic activity of the obtained samples was studied by the degradation of tetracycline hydrochloride under visible light irradiation. The results showed that Bi₂₄O₃₁Br₁₀ modified with the appropriate amount of WO₃ nanosheet exhibits higher catalytic activity and stability during the photocatalytic processes, and the holes (h⁺) is involved in the photolysis reaction as the main active species. The crystallization, morphology, optical and electrochemical properties of the as-prepared composite photocatalyst were characterized, and the mechanism of high photocatalytic activity was also explored. The optimal sample (10%-WO₃/Bi₂₄O₃₁Br₁₀) exhibited the best performance for tetracycline hydrochloride (TC) degradation, and more than 80% of the TC was degraded after 60 min under light irradiation. The degradation rate constant k was about 3.34-fold and 1.54-fold higher than pure WO₃ and Bi₂₄O₃₁Br₁₀, respectively. Its high photocatalytic performance can be attributed to the following reasons: the appropriate conduction band and valence band positions between WO₃ and Bi₂₄O₃₁Br₁₀, the close contact between the two visible light-driven photocatalysts, and the effective separation of the spatial charge. Our work may help to further expand the potential application of oxygen-rich bismuth oxyhalides photocatalyst in wastewater treatment, and provide a new strategy for the modification of nanostructured photocatalysts.     

Effects of sodium oleate on synthesis and photocatalytic activity of Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript>/Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>@RGO

In this study, the effects of sodium oleate on synthesis of Bi₂WO₆/Bi₂O₃ loaded reduced graphene oxide photocatalyst was studied. The as-prepared composites were characterized by X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance and photoluminescence spectroscopy. The results suggested that addition of sodium oleate not only promoted synthesis of Bi₂O₃, but also enhanced the reduction of GO to graphene. When the amount of sodium oleate was 4 mol (Bi:SO?=?1:1), Bi₂WO₆/Bi₂O₃@RGO to the best visible-light photocatalytic activity can be synthesized by a facile one-step solvothermal process without further reduction reaction. Hence, it indicated that sodium oleate could affect the synthesis of the as-prepared composites and the photocatalytic activity for degradation of RhB. This study did provide not only a facile method to synthesize Bi₂WO₆/Bi₂O₃@RGO, but also a method to reduce graphene oxide to graphene.     

Facile preparation and enhanced photocatalytic H2-production activity of Cu(OH)2 nanospheres modified porous g-C3N4

A facile precipitation approach for the preparation of Cu(OH)₂/g-C₃N₄ composite photocatalysts with good porous structure was developed for the first time. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible light (UV–vis) absorbance spectra, photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). A photocatalytic water splitting reaction on the as-prepared photocatalysts were carried out under visible light irradiation. The results revealed that the prepared samples showed significantly enhanced photocatalytic activity. The optimal Cu(OH)₂ loading content was found to be 0.34 mol%, giving an H₂-production rate of 48.7 μmol h⁻¹ g⁻¹, which is higher 16.5 times than that of pure g-C₃N₄. This high photocatalytic H₂-production activity is attributed to the presence of Cu(OH)₂ clusters on the surface of the porous g-C₃N₄, which efficiently promotes the visible light absorption and separation of photogenerated electron–hole pairs.     

Novel magnetically separable g-C3N4/Fe3O4/Ag3PO4/Co3O4 nanocomposites: Visible-light-driven photocatalysts with highly enhanced activity

In this study, a series of novel quaternary g-C₃N₄/Fe₃O₄/Ag₃PO₄/Co₃O₄ nanocomposites were fabricated. The prepared nanocomposites were characterized by XRD, EDX, SEM, TEM, UV-DRS, FT-IR, PL, TG, and VSM methods to gain insight about structure, purity, morphology, optical, thermal, and magnetic properties. Photocatalytic activity of the samples was investigated under visible-light irradiation by degradations of rhodamine B, methylene blue, methyl orange, and phenol as four organic pollutants. The highest photocatalytic degradation efficiency was observed when the sample calcined at 300 °C for 2 h with 20 wt% of Co₃O₄. The photocatalytic activity of this nanocomposite is almost 16.8, 15.7, 4.6, and 5.1 times higher than those of the g-C₃N₄, g-C₃N₄/Fe₃O₄, g-C₃N₄/Fe₃O₄/Ag₃PO₄ (20%), and g-C₃N₄/Fe₃O₄/Co₃O₄ (20%) samples in photodegradation of rhodamine B, respectively. Finally, on the basis of the energy band positions, the mechanism of enhanced photocatalytic activity was discussed.     

Synthesis and photocatalytic properties of HTaWO6/(Pt,TiO2) and HTaWO6/(Pt,Fe2O3) nanocomposites

HTaWO₆/(Pt,TiO₂) and HTaWO₆/(Pt,Fe₂O₃) nanocomposites were synthesized by successive intercalation reactions of HTaWO₆ with [Pt(NH₃)₄]Cl₂ aqueous solution, n-C₃H₇NH₂/n-heptane mixed solution and acidic TiO₂ colloid solution or [Fe₃(CH₃CO₂)₇(OH)(H₂O)₂]NO₃ aqueous solution followed by UV light irradiation. The gallery heights of HTaWO₆/(Pt,TiO₂), HTaWO₆/TiO₂, HTaWO₆/(Pt,Fe₂O₃) and HTaWO₆/Fe₂O₃ was less than 0.51 nm. The host HTaWO₆ was white possessing band gap energy of 3.1 eV, whereas HTaWO₆/Pt, HTaWO₆/(Pt,TiO₂), HTaWO₆/Fe₂O₃ and HTaWO₆/(Pt,Fe₂O₃) were yellow and showed broad reflection over 400–600 nm together with that corresponding to the host layer. Photocatalytic activities of HTaWO₆/TiO₂ and HTaWO₆/Fe₂O₃ were superior to those of unsupported TiO₂ and Fe₂O₃ and were greatly enhanced by co-incorporation of Pt. HTaWO₆/Pt, HTaWO₆/(Pt,TiO₂), HTaWO₆/Fe₂O₃ and HTaWO₆/(Pt,Fe₂O₃) showed photocatalytic activity.     

Monodisperse nanostructured Fe3O4/ZnO microrods using for waste water treatment

Monodisperse nanostructured Fe₃O₄/ZnO microrods were successfully prepared by an economic one-step synthesis route. The formation of nanostructured Fe₃O₄/ZnO microrods was evident from the detailed structural and elemental analysis by field emission scanning electronic microscopy, transmission electron microscopy, Raman spectra and X-ray photoelectron spectroscopy measurements. The formation mechanism of the hexagonal Fe₃O₄/ZnO microrods was carefully discussed. The removal of toxic metal ions experiments display that Fe₃O₄/ZnO heterostructures show the best removal efficiency compared with pure ZnO and Fe₃O₄ structures, and the photocatalytic experiments show that the Fe₃O₄/ZnO heterostructures display the excellent photocatalytic activity decomposing Rhodamine B (100% after 40 min).     

Bactericidal effect of blue LED light irradiated TiO2/Fe3O4 particles on fish pathogen in seawater

This study uses blue LED light (λ_max = 475 nm) activated TiO₂/Fe₃O₄ particles to evaluate the particles' photocatalytic activity efficiency and bactericidal effects in seawater of variable salinities. Different TiO₂ to Fe₃O₄ mole ratios have been synthesized using sol-gel method. The synthesized particles contain mainly anatase TiO₂, Fe₃O₄ and FeTiO₃. The study has identified TiO₂/Fe₃O₄'s bactericidal effect to marine fish pathogen (Photobacterium damselae subsp. piscicida BCRC17065) in seawater. The SEM photo reveals the surface destruction in bacteria incubated with blue LED irradiated TiO₂/Fe₃O₄. The result of this study indicates that 1) TiO₂/Fe₃O₄ acquires photocatalytic activities in both the freshwater and the seawater via blue LED irradiation, 2) higher photocatalytic activities appear in solutions of higher TiO₂/Fe₃O₄ mole ratio, and 3) photocatalytic activity decreases as salinity increases. These results suggest that the energy saving blue LED light is a feasible light source to activate TiO₂/Fe₃O₄ photocatalytic activities in both freshwater and seawater.