Fabrication of novel Nd2O3/ZnO-GO nanocomposite: An efficient photocatalyst for the degradation of organic pollutants

A novel CoMoO4 enwrapped ZIF-8 nanocomposite with enhanced visible light photocatalytic activity

A hybrid nano catalyst, CoMoO4 anchored zeolitic imidazolate framework-8 (ZIF-8) has been synthesized by simplest in-situ chemical method. The characterization results showed that the CoMoO4@ZIF-8 composites had a crystalline structure with a uniform distribution of the Cobalt molybdate particles on the ZIF-8 surface. The FTIR spectra revealed the presence of characteristic peaks for both ZIF-8 and CoMoO4, indicating the successful incorporation of the metal molybdate into the ZIF-8 framework. The SEM-EDS analysis showed that the CoMoO4 nanoparticles (NPs) have been evenly distributed on the ZIF-8 surface. In HRTEM, some rod-like CoMoO4 is observed on the surface of the ZIF-8 material, which is stacked in a disorderly manner and a porous channel structure is formed. The photocatalytic activity of the CoMoO4@ZIF-8 has been evaluated using the degradation of methylene blue (MB) and antibiotic Ciprofloxacin (CIP) under visible light. The optimal photocatalytic activity was achieved with the CoMoO4@ZIF-8 composite, which showed a degradation efficiency of 100% under visible light after 40 min of irradiation. In conclusion, the CoMoO4@ZIF-8 composites showed enhanced photocatalytic activity under visible light, and it exhibited the best performance compared with pure CoMoO4 and ZIF-8.

ZnO nanostructured matrix as nexus catalysts for the removal of emerging pollutants

Water pollution stands as a pressing global environmental concern, elevating the significance of innovative, dependable, and sustainable solutions. This study represents an extensive review of the use of photocatalytic zinc oxide nanoparticles (ZnO NPs) for the removal of emerging pollutants from water and wastewater. The study examines ZnO NPs' different preparation methods, including physical, chemical, and green synthesis, and emphasizes on advantages, disadvantages, preparation factors, and investigation methods for the structural and morphological properties. ZnO NPs demonstrate remarkable properties as photocatalysts; however, their small dimensions pose an issue, leading to potential post-use environmental losses. A strategy to overcome this challenge is scaling up ZnO NP matrices for enhanced stability and efficiency. The paper introduces novel ZnO NP composites, by incorporating supports like carbon and clay that serve as photocatalysts in the removal of emerging pollutants from water and wastewater. In essence, this research underscores the urgency of finding innovative, efficient, and eco-friendly solutions for the removal of emerging pollutants from wastewater and highlights the high removal efficiencies obtained when using ZnO NPs obtained from green synthesis as a photocatalyst. Future research should be developed on the cost-benefit analysis regarding the preparation methods, treatment processes, and value-added product regeneration efficiency.

Rational design of Nd2O3 decorated functionalized carbon nanofiber composite for selective electrochemical detection of carbendazim fungicides in vegetables, water, and soil samples

Abuse of carbendazim (CBZ) leaves excessive pesticide residues on agricultural products, which endangers human health because of the residues' high concentrations. Hence, a composite consisting of functionalized carbon nanofibers (f-CNF) with neodymium oxide (Nd₂O₃) was fabricated to monitor CBZ at trace levels. The Nd₂O₃/f-CNF composite-modified electrode displays higher electro-oxidation ability towards CBZ than Nd₂O₃ and f-CNF-modified electrodes. The combined unique properties of Nd₂O₃ and f-CNF result in a substantial specific surface area, superior structural stability, and excellent electrocatalytic activity of the composite yielding enhanced sensitivity to detecting CBZ with a detection limit of 4.3 nM. Also, the fabricated sensor electrode can detect CBZ in the linear concentration range of up to 243.0 μM with high selectivity, appropriate reproducibility, and stability. A demonstration of the sensing capability of CBZ in vegetables, water, and soil samples was reported paving the way for its use in practical applications.

Construction of single tungsten/copper atom oxide supported on the surface of TiO2 for the higher activity of electrocatalytic water splitting and photodegradation of organic pollutant

Intense studies are being carried out on single atom catalysts that exhibit remarkable activity and selectivity. To enhance their catalytic abilities, one must have a thorough understanding of the properties of the single metal atom active site and its dynamics in the working state. Herein, we report single metal atom oxide (SMAO) (metal: W/Cu) anchored on TiO₂-rGO nanomaterials (SMAO-ED-TiO₂-rGO) by simple sonication process. It is efficient for the electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and photocatalytic degradation of pharmaceutical pollutant. The uniform dispersion of the tungsten/copper metal atom oxide over a TiO₂-rGO materials is detected by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The SMAO-ED-TiO₂-rGO nanocatalyst has shown impressive HER/OER activity with an overpotential of 121/295 mV at (-)10 mA cm^-2 current density and the low Tafel slope of 96/60.3 mV dec^-1 in 1 M KOH solution. Further, SMAO-ED-TiO₂-rGO nanocatalyst was used for the photocatalytic degradation of ciprofloxacin (CF). After 60 min of UV light irradiation, the SMAO-ED-TiO₂-rGO nanocatalyst efficiently photodegraded 98.5% of CF while retaining its activity for five cycles. Superoxide radicals (O₂^•-) are found to be the main reactive species required in the photodegradation of CF, according to scavenger study of the SMAO-ED-TiO₂-rGO nanocatalyst for CF degradation.

Rational design of Ag2CO3-loaded SGO heterostructure with enhanced photocatalytic abatement of organic pollutants under visible light irradiation

The photocatalytic activity of semiconducting silver carbonate was restricted by the lower stability and fast recombination rate of photogenerated electron-hole pairs. Sulfur-doped graphene oxide (SGO) is used as a cocatalyst for improving the photocatalytic activity of Ag₂CO₃ by reducing the recombination rate. A simple precipitation method was used for the modification of silver carbonate. The chemical, physical, optical, and electrochemical properties of the modified photocatalyst was characterized by XRD, SEM, TEM, UV-vis DRS, XPS, CV, impedance, and amperometry. The fabricated SGO-Ag₂CO₃ composite was successfully degraded various organic pollutants such as methylene blue (MB), rhodamine B(RhB), methyl orange (MO), tartrazine, and thiram with augmented mineralization. The optimization of weight percentage of the developed binary composite with 0.5% SGO-Ag₂CO₃ showed enhanced photocatalytic degradation and followed pseudo-first-order kinetics with rate constant 0.126. More than 90% of degradation efficiency of the pollutants within a short time promises the binary heterostructure for future industrial applications. The excellent stability and reproducibility of the composite opened a new route in the treatment of wastewater.

The Photocatalytic Performance of Nd2O3 Doped CuO Nanoparticles with Enhanced Methylene Blue Degradation: Synthesis, Characterization and Comparative Study

The growth of the textile industry results in a massive accumulation of dyes on water. This enormous rise in pigments is the primary source of water pollution, affecting the aquatic lives and our ecosystem balance. This study aims to notify the fabrication of neodymium incorporated copper oxide (Nd2O3 doped CuO) nanoparticles by combustion method for effective degradation of dye, methylene blue (MB). X-ray diffraction (XRD), Field emission Scanning electron microscopy (FESEM), Zeta potential have been applied for characterization. Photocatalyst validity has been evaluated for methylene blue degradation (MB). Test conditions such as time of contact, H2O2, pH, and photo-Fenton have been modified to identify optimal degradation conditions. Noticeably, 7.5% Nd2O3 doped CuO nanoparticle demonstrated the highest photocatalytic efficiency, up to 90.8% in 80 min, with a 0.0227 min-1 degradation rate. However, the photocatalytic efficiency at pH 10 becomes 99% with a rate constant of 0.082 min-1. Cyclic experiments showed the Nd2O3 doped CuO nanoparticle's stability over repeated use. Scavenge hydroxyl radical species responsible for degradation using 7.5% Nd2O3 doped CuO nanoparticles have been investigated under visible irradiation.

CQDs/ZnO composites based on waste rice noodles: preparation and photocatalytic capability

To provide a low-cost photocatalyst and new methodology for the utilization of waste rice noodle (WRN), a carbon quantum dots/zinc oxide (CQDs/ZnO) composite using WRN as the raw material was synthesized and characterized. The CQDs/ZnO composite based on WRN exhibited a highly efficient photocatalytic degradation effect on various organic pollutants and could be a good alternative for commercial ZnO. For methylene blue, the CQDs/ZnO composite showed a good degradation rate of 99.58% within 40 min, a high degradation rate constant of 0.2630 min⁻¹, and could be recycled and reused for ten photocatalytic cycles without an appreciable decrease in the degradation effect, which was much better than that of commercial ZnO. The resulting CQDs/ZnO composite also displayed a nice photocatalytic degradation effect on other common organic pollutants, such as malachite green, methyl violet, basic fuchsin, rhodamine B, aniline and tetracycline. In particular, it could achieve excellent photocatalytic degradation on malachite green with an extremely high degradation rate constant of 1.9260 min⁻¹. Besides, the CQDs/ZnO composite could also be used to control the pollution of tetracycline or aniline. The introduction of CQDs based on WRN to ZnO resulted in efficient electron–hole pair separation and enabled more photogenerated electrons to reduce O₂ and more photogenerated holes to oxidize H₂O, which caused stronger abilities in producing radicals (such as O₂˙⁻ and ˙OH) and a better photocatalytic degradation effect to organic pollutants.

A CQDs/ZnO composite based on waste rice noodles displayed a highly efficient photocatalytic degradation effect on various organic pollutants.

An overview on non-spherical semiconductors for heterogeneous photocatalytic degradation of organic water contaminants

Because of their carcinogenicity and mutagenicity, the elimination of organic contaminants from surface and subsurface water is a subject of environmental significance. Conventional water decontamination approaches such as membrane separation, ultrafiltration, adsorption, reverse osmosis, coagulation, etc., have relatively higher operating costs and can generate highly toxic secondary contaminants. On the other hand, heterogeneous photocatalysis, an advanced oxidation process (AOP), is considered a clean and cost-effective process for organic pollutants degradation. Owing to their distinctive structure and physicochemical properties non-spherical semiconductors have gained considerable limelight in the photocatalytic degradation of organic contaminants. The current review briefly introduces a wide range of organic water contaminants. Recent advances in non-spherical semiconductor assembly and their photocatalytic degradation applications are highlighted. The underlying mechanism, fundamentals of photocatalytic reactions, and the factors affecting the degradation performance are also alluded including the current challenges and future research perspectives.

Synthesis of CoCrFeO4-chitosan beads sun-light-driven photocatalyst with well recycling for efficiently degrading high-concentration dyes

It is highly desired to develop an efficient large surface area CoCrFeO₄-based beads sun-light driven photocatalysts with excellent recycling features for degrading high-concentration dyes. Herein, a novel CoCrFeO₄ oxide nanoparticles have customarily been synthesized by the combination of three metals (Co, Cr and Fe) via co-precipitation method in aqueous solution and then millimeter-scale CoCrFeO₄ oxide chitosan-composite beads (CoCrFeO₄-CB) were prepared by incorporating the CoCrFeO₄ in chitosan polymer in basic medium, which makes the adsorbent easier to separate. The number of optimized nanocomposite beads used for the removal of high-concentration dyes displays 5-time photoactivity enhancement under sun-light irradiation compared to pristine CoCrFeO₄. Based on the fluorescence spectra related to the formed OH amounts, temperature-programmed desorption and electrochemical results, it is deduced that the unprecedented photocatalytic activities are mainly attributed to the large surface area, and enhanced charge separation from the chitosan as well as its promotion effects on O₂ activation. Influencing factors that effect the photocatalytic efficiency of dyes, such as catalyst dose, dyes concentration, time, and the light source was also studied. More importantly, after five catalytic cycles, no evident deactivation was observed, suggesting the satisfactory stability of the investigated photocatalyst. Also, large numbers of superoxides radicals form which is the main active species participate in the degradation of acid black were analyzed using a radical trapping experiment. It is expected that our work could render navigated information for steering toward the design and applications of the CoCrFeO₄-based photocatalyst with sun-light utilization for environmental remediation.

A comprehensive study on the application of FeNi3@SiO2@ZnO magnetic nanocomposites as a novel photo-catalyst for degradation of tamoxifen in the presence of simulated sunlight

Pharmaceutical compounds at trace concentrations are found in the environment, especially in drinking water and food, posing significant negative effects on humans as well as on animals. This paper aimed to examine the diagnostic catalytic properties and efficacy of a novel synthesized photocatalyst, namely FeNi₃@SiO₂@ZnO magnetic nanocomposite, for the removal of tamoxifen (TMX) from wastewater under simulated sunlight. According to the results, it was found that TMX was completely degraded operating under optimized conditions (i.e. pH = 7, catalyst dose = 0.01 g/L, initial TMX concentration = 20 mg/L and reaction time = 60 min). The reaction kinetics of TMX degradation followed a pseudo-first order kinetics model. The final by-products from the TMX photodegradation were water, carbon dioxide, acetic acid, nitroacetic acid methyl ester, 2-methyl-2-pentenal, and 4-methyl-2-pentanol. In addition, the synthesized photocatalyst could successfully performed five consecutive photodegradation cycles. The obtained results revealed that the synthesized FeNi₃@SiO₂@ZnO magnetic nanocomposite holds a great potential to be applied as a photocatalyst for the degradation of TMX on an industrial scale.