Search Results (8)

The introduction of oxygen vacancies (OVs) is a promising strategy to enhance the hydrogen (H₂) evolution efficiency of photocatalysts. Sodium borohydride (NaBH₄) is widely used as a reducing agent to introduce OVs, particularly in composite materials. However, its impact on H₂ evolution remains underexplored. In this study, by employing various mass ratios of NaBH₄ to P/Ag/Ag₂O/Ag₃PO₄/TiO₂ (PAgT), OVs modified PAgT (R-PAgT) composites, which were synthesized and systematically characterized by XRD, FT-IR, and XPS. R-PAgT-10 with an optimal mass ratio exhibited a superior H₂ evolution efficiency and stability, maintaining its performance over 20 cycles under visible light irradiation, while the higher mass ratio of NaBH₄/PAgT led to the disruption of the crystal structure with excessive OVs amounts, resulting in poor stability. This study highlighted the importance of utilizing the optimal mass ratio of NaBH₄ to prepare OVs-PAgT for successful and stable H₂ evolution under visible light irradiation, which holds promise for developing efficient and durable photocatalysts for renewable energy applications. Full article

In order to improve the photocatalytic performance of g-C₃N₄, the g-C₃N₄/Ti₃C₂/Ag₃PO₄ S-type heterojunction catalyst was prepared by electrostatic assembly method, and then the g-C₃N₄/Ti₃C₂/Ag₃PO₄/PAN composite nanofiber membrane was prepared by electrospinning technology. The morphology and chemical properties of the nanofiber membrane were characterized by SEM, FTIR, and XRD, and the photocatalytic degradation of tetracycline hydrochloride (TC) in water by the nanofiber membrane was investigated. The results showed that g-C₃N₄/Ti₃C₂/Ag₃PO₄ could be successfully loaded on PAN and uniformly distributed on the surface of composite nanofiber membrane by electrospinning technology. Increasing the amount of loading and catalyst, lowering the pH value and TC concentration of the system were conducive to the oxidation and degradation of TC. The nano-fiber catalytic membrane had been recycled five times and found to have excellent photocatalytic stability and reusability. The study of catalytic mechanism showed that h⁺, •OH and •O₂⁻ were produced and participated in the oxidation degradation reaction of TC, and •O₂⁻ plays a major role in catalysis. Therefore, this work provides a new insight into the construction of high-performance and high-stability photocatalytic system by electrospinning technology. Full article

Solar light active photocatalyst was prepared as silver phosphate (Ag₃PO₄) coating on titania–silica (TiO₂–SiO₂) microspheres. Titania–silica microsphere was obtained by spray drying TiO₂–SiO₂ colloidal solutions, whereas Ag₃PO₄ was applied by wet impregnation. XRD on the granules and SEM analysis show that the silver phosphate particles cover the surface of the titania–silica microspheres, and UV-visible diffuse reflectance analysis highlights that Ag₃PO₄/TiO₂–SiO₂ composites can absorb the entire visible light spectrum. BET measurements show higher specific surface area of the composite samples compared to bare Ag₃PO₄. Photocatalytic activity was evaluated by dye degradation tests under solar light irradiation. The prepared catalysts follow a pseudo-first-order rate law for dye degradation tests under solar light irradiation. The composite catalysts with an Ag₃PO₄/TiO₂–SiO₂ ratio of 1:1.6 wt% show better catalytic activity towards both rhodamine B and methylene blue degradation and compared with the results with uncoated TiO₂–SiO₂ microspheres and the benchmark commercial TiO₂ (Evonik-P25) as a reference. The composite photocatalyst showed exceptional efficiency compared to its pristine counterparts and reference material. This is explained as having a higher surface area with optimum light absorption capacity. Full article

Two-dimensional Ti₃C₂ MXenes can be used to fabricate hierarchical TiO₂ nanostructures that are potential photocatalysts. In this study, the photodecomposition of organic dyes under solar light was investigated using flower-like TiO₂@Ti₃C₂, deposited using narrow bandgap Ag₃PO₄. The surface morphology, crystalline structure, surface states, and optical bandgap properties were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption analysis, and UV-Vis diffuse reflectance spectroscopy (UV-DRS). Overall, Ag₃PO₄-deposited TiO₂@Ti₃C₂, referred to as Ag₃PO₄/TiO₂@Ti₃C₂, demonstrated the best photocatalytic performance among the as-prepared samples, including TiO₂@Ti₃C₂, pristine Ag₃PO₄, and Ag₃PO₄/TiO₂ P25. Organic dyes, such as rhodamine B (RhB), methylene blue (MB), crystal violet (CV), and methylene orange (MO), were efficiently degraded by Ag₃PO₄/TiO₂@Ti₃C₂. The significant enhancement of photocatalysis by solar light irradiation was attributed to the efficient deposition of Ag₃PO₄ nanoparticles on flower-like TiO₂@Ti₃C₂ with the efficient separation of photogenerated e-/h+ pairs, high surface area, and extended visible-light absorption. Additionally, the small size of Ag₃PO₄ deposition (ca. 4–10 nm diameter) reduces the distance between the core and the surface of the composite, which inhibits the recombination of photogenerated charge carriers. Free radical trapping tests were performed, and a photocatalytic mechanism was proposed to explain the synergistic photocatalysis of Ag₃PO₄/TiO₂@Ti₃C₂ under solar light. Full article

In this study, the ability of Ag₃PO₄ to achieve the photocatalytic degradation of quinoline yellow (QY) a hazardous and recalcitrant dye, under UVA and visible light was investigated. The photocatalyst Ag₃PO₄ was synthesized through a precipitation method, and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), BET Brunauer–Emmett-Teller (BET) analysis, UV-Differential Reflectance Spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR). Ag₃PO₄ could successfully induce the photocatalytic degradation of QY under UVA and visible light. Optimal parameters were 0.5 g·L⁻¹ of the catalyst, 20 ppm of QY and pH~7. Ag₃PO₄ was 1.6-times more efficient than TiO₂ Degussa P25 under UV_A light in degrading QY. Total organic carbon (TOC) analyses confirmed the almost complete QY mineralization. At least eight intermediate degradation products were identified by liquid chromatography coupled to high resolution mass spectrometry. The stability of Ag₃PO₄ was satisfactory as less than 5% Ag metal appeared in XRD analyses after 3 reuse cycles. These results show that under optimized conditions Ag₃PO₄ can efficiently achieve quinolone yellow mineralization. Full article

Composites comprised of Ag₃PO₄ and bare TiO₂ (TiO₂@Ag₃PO₄) or silver doped TiO₂ (Ag@TiO₂–Ag₃PO₄) have been synthesized by coupling sol–gel and precipitation methods. For the sake of comparison, also the bare components have been similarly prepared. All the samples have been characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), photoelectrochemical measurements, and specific surface area (SSA) analysis. The optoelectronic and structural features of the samples have been related to their photocatalytic activity for the degradation of 4–nitrophenol under solar and UV light irradiation. Coupling Ag₃PO₄ with silver doped TiO₂ mitigates photocorrosion of the Ag₃PO₄ counterpart, and remarkably improves the photocatalytic activity under solar light irradiation with respect to the components, to the TiO₂–Ag₃PO₄ sample, and to the benchmark TiO₂ Evonik P25. These features open the route to future applications of this material in the field of environmental remediation. Full article

Photocatalytic fuel cells (PFCs) are a sustainable technology with application in waste water treatment, in which energy is obtained from the photocatalytic degradation of organic pollutants. However, the application of PFCs is limited by the photoanode, in particular its low efficiency for treating recalcitrant pollutants. In this study, a double chamber PFC reactor was constructed. Visible-light-driven Ag-TiO₂ photocatalyst supported carbon foam was used as the anode and platinum was used as the cathode. 4-Chlorophenol (4-CP) was used as a model pollutant in the cation chamber to investigate the efficiency of pollutant degradation and power generation. The effects of the electrolyte type and solution pH on the 4-CP degradation and power production were investigated. The results showed that 32.6% of 4-CP was degraded by the PFC in 6 h. Na₂SO₄ was the optimum electrolyte and had the least side effects on the degradation of 4-CP when compared with NaCl, NaHCO₃ and NaH₂PO₄. The optimum pH range was 6.4–8.4 when sodium sulfate was used as the electrolyte. The power density was approximately 36.0 mW/m² under the above experimental conditions. Full article

Self-organized TiO₂ nanotube layer has been formed on titanium screws with complex geometry, which are used as dental implants. TiO₂ nanotubes film was grown by potentiostatic anodizing in H₃PO₄ and HF aqueous solution. During anodizing, the titanium screws were mounted on a rotating apparatus to produce a uniform structure both on the peaks and on the valleys of the threads. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) and electrochemical characterization were used to evaluate the layer, chemical composition and electrochemical properties of the samples. Aging in Hank’s solution of both untreated and nanotubes covered screw, showed that: (i) samples are covered by an amorphous oxide layer, (ii) the nanotubes increases the corrosion resistance of the implant, and (iii) the presence of the nanotubes catalyses the formation of chemical compounds containing Ca and P. Full article