Nano-zirconia supported by graphitic carbon nitride for enhanced visible light photocatalytic activity

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.

Te4+ and Er3+ doped ZrO2 nanoparticles with enhanced photocatalytic, antibacterial activity and dielectric properties: A next generation of multifunctional material

Amid rising water contamination from industrial sources, tackling toxic dyes and pathogens is critical. Photocatalysis offers a cost-effective and eco-friendly solution to this pressing challenges. Herein, we synthesized Te4+ and Er3+ doped ZrO2 photocatalysts through hydrothermal method and investigated their efficacy in degrading Congo red (CR) and pathogens under visible light. XRD and Raman Spectroscopy confirm monoclinic and tetragonal mixed-phases without any impurities. Doping-induced defects, reduced crystalline diameter, high surface area, modified bandgap (2.95 eV), photoluminescence quenching, coupled with interfacial polarization, contribute to EZO's excellent dielectric response (1.149 × 106), for achieving remarkable photocatalytic activity, verified by photoelectrochemical measurements, LC-MS and phytotoxicity analysis. Under optimal conditions, EZO achieves 99% CR degradation within 100 min (TOC 79.9%), surpassing ZO (77%) and TZO (84%). Catalyst dosages, dye concentrations, and solution pH effect on EZO's photocatalytic performance are systematically assessed. Scavenging experiment emphasized the pivotal role of · OH in CR degradation with 96.4% efficiency after 4 cycles, affirming its remarkable stability. Moreover, EZO demonstrates ROS-mediated antibacterial activity against E. faecalis and E. coli bacteria under visible light, achieving >97% and >94% inhibition rate with an inhibition zone > 3 mm. Hence, the nanoparticle's dual action offers a practical solution for treating contaminated wastewater, ensuring safe irrigation.

Synthesis of CeO2/ZrO2/ZnO nano alloy oxide and investigation of photocatalysis of naphthol orange under sunlight

Novel metal-like cerium- and zirconium-doped ZnO photocatalysts were prepared herein with various proportions of molar ratios via a cost-effective co-precipitation method. The effects of novel metal doping on the photocatalytic activity of ZnO were studied. Various techniques were used to investigate the structural, morphological, and elemental composition, particle size, optical properties, and catalytic activity of the synthesized photocatalysts. It was found that the crystallite size and particle size of the nano alloy oxides were 15.12 ± 1 and 5 ± 1 nm, respectively, and the surface morphology of the nanoparticles indicated a satisfactory surface area. Among all synthesized nanocomposites, Ce_xZr_xZn_xO₅ (x = 1) [CZ₁Z₂-A] exhibited satisfactory photo-oxidation activity against naphthol orange (NO) under sunlight with a rate constant of 57.5 × 10^-3 min^-1. The effects of pH, inorganic salts, dye concentrations, and catalytic dosage on NO degradation were studied. A probable mechanistic pathway for the degradation of NO in the presence of CZ₁Z₂-A was proposed, and studies of sacrificial agents indicated that superoxide radical anion (O₂˙^-) was the main accountable active species in NO degradation. In addition, CZ₁Z₂-A exhibited excellent recyclability potential, and XRD studies revealed that there was no change in the crystal structure before or after degradation, which indicated its high stability. The intriguing finding was that Ce- and Zr-doped ZnO did not exhibit satisfactory catalytic performance in the photo-oxidation of NO. However, the composite formula of Ce_xZr_xZn_xO₅ (x = 1) with a 1 : 1 : 1 ratio of metal ions offered excellent catalytic activity.

Yolk@Wrinkled-double shell smart nanoreactors: new platforms for mineralization of pharmaceutical wastewater

Nanomaterials with "yolk and shell" "structure" can be considered as "nanoreactors" that have significant potential for application in catalysis. Especially in terms of electrochemical energy storage and conversion, the nanoelectrode has a large specific surface area with a unique yolk@shell structure, which can reduce the volume change of the electrode during the charging and discharging process and fast ion/electron transfer channels. The adsorption of products and the improvement of conversion reaction efficiency can greatly improve the stability, speed and cycle performance of the electrode, and it is a kind of ideal electrode material. In this research, heterojunction nanoreactors (FZT Y@WDS) Fe3O4@ZrO2-X@TiO2-X were firstly synthesized based on the solvothermal combined hard-template process, partial etching and calcination. The response surface method was used to determine the performance of the FZT Y@WDS heterojunction nanoreactors and the effects of four process factors: naproxen concentration (NAP), solution pH, the amount of charged photocatalyst, and the irradiation time for photocatalytic degradation of NAP under visible light irradiation. To maximize the photocatalytic activity, the parameters of the loaded catalyst, the pH of the reaction medium, the initial concentration of NAP, and the irradiation time were set to 0.5 g/L, 3, 10 mg/L, and 60 min, respectively, resulting in complete removal of NAP and the optimum amount was calculated to be 0.5 g/L, 5.246, 14.092 mg/L, and 57.362 min, respectively. Considering the promising photocatalytic activity of FZT Y@WDS under visible light and the separation performance of the nanocomposite, we proposed this photocatalyst as an alternative solution for the treatment of pharmaceutical wastewater.

Highly dispersed g-C3N4 on well-designed three-dimensional porous nanostructured ZrO2 for high-performance photocatalytic degradation and H2 production

A novel polymer-assisted freeze-drying method was adopted for preparing three-dimensional porous nanostructured ZrO₂ (3DPZ) with macro self-supporting properties. Then, g-C₃N₄ was in-situ grown uniformly on the 3DPZ through a gas-solid reaction, forming 3D nanoporous ZrO₂/g-C₃N₄ heterojunctions (3DP/ZC) with different g-C₃N₄ loadings that retained self-supporting characteristics. The k_app value of Rhodamine B (RhB) degradation and H₂ evolution rate of the 3DP/ZC-2 under visible light reached 0.035 min^-1 and 1013.1 μmol h^-1 g^-1, which were 19.6 and 6.6 times higher than pure g-C₃N₄, respectively. The ZrO₂ nanoparticles (ZNps) prepared via freeze-drying, but without polymer precursor, were used as support to form ZrO₂/g-C₃N₄ nanoparticles (ZCNps-2) for comparison study. The RhB degradation rate and H₂ evolution rate of the 3DP/ZC-2 under visible light were about 3.7 and 5.3 times higher than ZCNps-2. Their enhanced photocatalytic activity could be attributed to their unique 3D heterointerface with matched energy bands for rapid charge separation and transfer and a hierarchical porous structure for mass transfer and surface reaction processes. The scavenger trapping and ESR measurements confirmed that the primary reactive radicals for degradation were superoxide radical ions (^⋅O₂^-), hydroxyl radicals (^⋅OH), and photogenerated holes (h⁺). The pH-dependent photocatalytic degradation activity originated from the H⁺-related ^⋅OH conversion reaction. Besides, the macro self-supporting nature could provide excellent separability and recyclability, and self-supporting membranes were also constructed and demonstrated as stable and recyclable photocatalysts. This work provides a new routine for designing 3D-heterojunctions as new kinds of functional materials for applications in environmental remediation and green energy production.

Nanocomposites with ZrO2@S-Doped g-C3N4 as an Enhanced Binder-Free Sensor: Synthesis and Characterization

This study describes new electrocatalyst materials that can detect and reduce environmental pollutants. The synthesis and characterization of semiconductor nanocomposites (NCs) made from active ZrO₂@S-doped g-C₃N₄ is presented. Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) measurements were used to examine electron transfer characteristics of the synthesized samples. Using X-ray diffraction (XRD) and high-resolution scanning electron microscopy (HR-SEM) techniques, inclusion of monoclinic ZrO₂ on flower-shaped S-doped-g-C₃N₄ was visualized. High-resolution X-ray photoelectron spectroscopy (XPS) revealed successful doping of ZrO₂ into the lattice of S-doped g-C₃N₄. The electron transport mechanism between the electrolyte and the fluorine tin-oxide electrode (FTOE) was enhanced by the synergistic interaction between ZrO₂ and S-doped g-C₃N₄ as co-modifiers. Development of a platform with improved conductivity based on an FTOE modified with ZrO₂@S-doped g-C₃N₄ NCs resulted in an ideal platform for the detection of 4-nitrophenol (4-NP) in water. The electrocatalytic activity of the modified electrode was evaluated through determination of 4-NP by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) under optimum conditions (pH 5). ZrO₂@S-doped g-C₃N₄ (20%)/FTOE exhibited good electrocatalytic activity with a linear range from 10 to 100 μM and a low limit of detection (LOD) of 6.65 μM. Typical p-type semiconductor ZrO₂@S-doped g-C₃N₄ NCs significantly impact the superior detection of 4-NP due to its size, shape, optical properties, specific surface area and effective separation of electron-hole pairs. We conclude that the superior electrochemical sensor behavior of the ZrO₂@S-doped g-C₃N₄ (20%)/FTOE surfaces results from the synergistic interaction between S-doped g-C₃N₄ and ZrO₂ surfaces that produce an active NC interface.

Graphitic carbon nitride with thermally-induced nitrogen defects: an efficient process to enhance photocatalytic H2 production performance

An efficient thermal-treatment method was developed for the preparation of defect modified g-C₃N₄ with excellent photocatalytic H₂ production performance.