Fabrication of RuO2-Ag3PO4 heterostructure nanocomposites: Investigations of band alignment on the enhanced visible light photocatalytic activity

Preparation of thiourea derivative incorporated Ag3PO4 core shell for enhancement of photocatalytic degradation performance of organic dye under visible radiation light

Photocatalysis is a promising technique to reduce hazardous organic pollutants using semiconductors under visible light. However, previous studies have been concerned with the behavior of silver phosphate (Ag3PO4) as n-type semiconductors, and the problem of their instability is still under investigation. Herein, 4,4'-(((oxalylbis(azanediyl)) bis(carbonothioyl)) bis(azanediyl)) dibenzoic acid is synthesized by green method and used to enhance the photocatalytic behavior for Ag3PO4. The incorporated Ag3PO4 core-shell is prepared and characterized via XRD, FT-IR, Raman, TEM and BET. Besides, the thermal stability of the prepared core shell was investigated via TGA and DSC measurements. The optical properties and the energy band gap are determined using photoluminescence and DRS measurements. The photodegradation of methylene blue in the presence of the synthesized Ag3PO4 core-shell under visible light is examined using UV/Vis measurements. The effect of initial dye concentration and contact time are studied. In addition, the kinetic behavior of the selected dye during the photodegradation process shows a pseudo-first order reaction with rate constant of 0.015 min-1 for ZAg. The reusability of the Ag3PO4 core shell is evaluated, and the efficiency changed from 96.76 to 94.02% after three cycles, indicating efficient photocatalytic behavior with excellent stability.

Improvement of photocatalytic degradation of methyl orange by impregnation of natural clay with nickel: optimization using the Box-Behnken design (BBD)

In this research work, the photocatalytic degradation of methyl orange dye was studied on nickel oxide supported on a natural Moroccan clay (Ni/NC). These catalysts have been prepared by dry impregnation of a nickel nitrate solution with different weight percentages (5, 10, 20% NiO). Experimental responses were obtained by a Box-Behnken (BBD) experimental design by varying the catalyst mass, solution pH, and initial dye concentration at three levels (low, medium, and high). The prepared catalysts were characterized using powder X-ray diffraction (XRD) to assess crystallinity and structure, Fourier transform infrared spectroscopy (FTIR) to detect different functional groups, scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis to study the surface morphology, and the optical characteristics of the catalysts were studied using absorption and diffuse reflectance measurements in the UV-visible range. The photocatalytic activity of the catalysts was evaluated in aqueous solutions under UV irradiation. ANOVA (analysis of variance) test is employed to recognize the significant factors and their interactions and then give the model equation for the percent dye degradation. The optimal values of the studied factors were determined by numerical optimization, and the results showed that about 100% degradation of the methyl orange dye could be achieved under the following optimal conditions, which are pH = 4.38, catalyst concentration of 0.99 g/L, and initial dye concentration of 30.42 mg/L.

Fabrication of Ag3PO4/polyaniline-activated biochar photocatalyst for efficient triclosan degradation process and toxicity assessment

Triclosan (TCS) is a typical environmental pollutant, which seriously threatens the health of humans and organisms. A novel strategy of biochar/Ag₃PO₄/polyaniline (PANI) composite photocatalyst was synthesized by a facile chemical precipitation method to efficiently degrade TCS. XRD, Raman, ESR, etc. were used to reveal the effective associations among physiochemistry, photochemistry and photocatalytic properties of the composite. It was proved the synergistic effects of biochar (T-Bio) and PANI resulted in the decrease of Ag₃PO₄ particle size, the enhancement of adsorption, the improvement of light utilization, the increase of photogenerated carrier separation and the promotion of reactive species. The photocatalytic mechanism showed h⁺ was the main active species, O₂^- and OH played minor roles. Under the irradiation of visible light, the optimal photocatalyst (1.0% T-Bio/AP/1.0% PANI) displayed excellent photocatalytic activity with the removal rate of 85.21% for TCS within 10 min, and the apparent rate constant K' was 2.38 times of Ag₃PO₄. 11 main intermediates for TCS degradation were identified, and their toxicity was significantly reduced. The possible degradation pathways were proposed. This work is the first systematic study on the degradation behavior of TCS by Ag₃PO₄-based photocatalyst, and it provides a new approach to fabricate photocatalysts with synergistic effects and amazing photocatalytic activity by biochar.

Magnetically separable BiOBr/Fe3O4@SiO2 for visible-light-driven photocatalytic degradation of ibuprofen: Mechanistic investigation and prototype development

The increasingly ubiquitous release of emerging refractory pollutants into water is a serious concern due to associated risks. In this study, mesoporous hierarchical BiOBr/Fe₃O₄@SiO₂-a solvothermally synthesized visible-light-driven magnetic photocatalyst-not only exhibited fast kinetics (t_1/2 = 8.7 min) in the photocatalytic degradation of ibuprofen in water but also achieved almost complete mineralization over a prolonged irradiation of 6 h. Various reactive species, including O₂¯, OH, and H₂O₂, were detected, while the scavenging experiments revealed that e_CB^--mediated reactions and direct-hole oxidation are the major degradation routes. The magnetically recycled BiOBr/Fe₃O₄@SiO₂ maintained ∼80% of its initial photocatalytic activity even after five consecutive cycles. The typically copresent wastewater constituents, including NOM and anions, inhibited the photocatalytic performance to varying extents, and hence necessitated an increase in the photocatalyst dosage to achieve complete ibuprofen degradation in real sewage. Based on the findings of batch experiments, the process was scaled up by developing a 5 L prototype photocatalytic reactor integrated with an electromagnetic separation unit. The results of prototype photocatalytic experiments were comparable to those of batch experiments, and an electromagnetic separation efficiency of ∼99% was achievable in 5 min.

Hybrid nanostructures of pit-rich TiO2 nanocrystals with Ru loading and N doping for enhanced solar water splitting

Hybrid nanostructures of pit-rich TiO₂ nanocrystals with ruthenium loading and nitrogen-doping exhibited enhanced solar water splitting.

Synthesis and characterization of a heterojunction rGO/ZrO2/Ag3PO4 nanocomposite for degradation of organic contaminants

Synergy between surface adsorption and photocatalysis is key for effective contaminant degradation in the liquid phase. Herein, we report a heterojunction photocatalyst of reduced graphene oxide (rGO)/zirconium dioxide (ZrO₂)/silver phosphate (Ag₃PO₄) that incorporates this synergy for 4-nitrophenol (PNP) removal. Compared with other photocatalyst combinations, ZrO₂ and Ag₃PO₄ coupling generates reactive species with greater degradation potential. ZrO₂ and rGO were synthesized by a green approach using a one-step hydrothermal reaction in ethanol-water. The growth of rGO/ZrO₂ and Ag₃PO₄ were accomplished and the functions of each part were well developed together. The rGO/ZrO₂/Ag₃PO₄ composite exhibited enhanced light absorption and a low band gap energy (2.3 eV) owing to rGO and Ag₃PO₄ integration. The composite's photocatalytic activity was much higher than that of ZrO₂, Ag₃PO₄, or ZrO₂/Ag₃PO₄. The maximal adsorption of PNP was 26.88 mg/g, and a pseudo-first-order model described the PNP degradation kinetics (k = 0.034 min^-1). Synergy between the three components resulted in 97% PNP removal in 90 min, and even after five cycles, 94% PNP removal was obtained. The quantum yield of the system (7.31 × 10^-5 molecules/photon) was compared with those in previous reports to assess the photocatalytic performance and energy requirements.