Visible Light Sensitive SnO2/ZnCo2O4 Material for the Photocatalytic Removal of Organic Pollutants in Water

ZnCo2O4@g-C3N4@Cu as a new and highly efficient heterogeneous photocatalyst for visible light-induced cyanation and Mizoroki-Heck cross-coupling reactions

Conducting C-C cross-coupling reactions under convenient and mild conditions remains extremely challenging in traditional organic synthesis. In this study, ZnCo2O4@g-C3N4@Cu exhibited extraordinary photocatalytic performance as a new visible light harvesting heterogeneous copper-based photocatalyst in cyanation and Mizoroki-Heck visible-light-driven cross-coupling reactions at room temperature and in air. Surprisingly, by this method, the cyanation and Mizoroki-Heck cross-coupling reactions of various iodo-, bromo- and also the challenging chloroarenes with respectively K4[Fe(CN)6]·3H2O and olefins produced promising results in a sustainable and mild media. The significant photocatalytic performance of ZnCo2O4@g-C3N4@Cu arises from the synergistic optical properties of ZnCo2O4, g-C3N4, and Cu. These components can enhance the charge carrier generation and considerably reduce the recombination rate of photogenerated electron-hole pairs. No need to use heat or additives, applying an economical and benign light source, utilizing an environmentally compatible solvent, facile and low-cost photocatalytic approach, aerial conditions, high stability and convenient recyclability of the photocatalyst are the remarkable highlights of this methodology. Moreover, this platform exhibited the ability to be performed on a large scale, which is considered an important issue in industrial and pharmaceutical use. It is worth noting that this is the first time that a heterogeneous copper-based photocatalyst has been employed in visible light-promoted cyanation reactions of aryl halides.

Fabrication of a highly efficient CuO/ZnCo2O4/CNTs ternary composite for photocatalytic degradation of hazardous pollutants

In the current study, CuO, ZnCo2O4, CuO/ZnCo2O4, and CuO/ZnCo2O4/CNTs photocatalysts were prepared to remove crystal violet (CV) and colorless pollutants (diclofenac sodium and phenol) from wastewater. Herein, sol-gel and co-precipitation methods were used to synthesize CuO and ZnCo2O4, respectively. The sonication method was used to synthesize CuO/ZnCo2O4 and a CNTs-based composite (CuO/ZnCo2O4/CNTs). From the UV-Vis spectra of CuO, ZnCo2O4, CuO/ZnCo2O4, and CuO/ZnCo2O4/CNTs, the optical band gap value was calculated to be 2.11, 2.18, 1.71 and 1.63 eV respectively. The photocatalytic results revealed that CuO/ZnCo2O4/CNTs exhibited higher degradation of 87.7% against CV dye, 82% against diclofenac sodium, and 72% against phenol as compared to other prepared photocatalysts. The OH˙ radical is identified as the active species in the photocatalytic process over CuO/ZnCo2O4/CNTs. The impact of several parameters, such as pH, concentration, and catalyst dosage, has also been investigated. The better activity of the CNTs-based composite was due to the synergic effect of both CuO/ZnCo2O4 nanocomposite and carbon nanotubes. Therefore, the synthesized CuO/ZnCo2O4/CNTs photocatalyst has the potential to degrade organic wastewater effluents effectively.

Coastal aquatic pollutants degradation using ZnCo2O4 nanorods

Water pollution has caused problems in coastal areas, rivers, lakes, and other important water sources around the world as a result of inappropriate waste management. Meanwhile, these pollutants are harmful to humans and aquatic life. Textile dye effluent methyl orange (MO) was used in this work for dye degradation studies employing nanocomposites. As a result, the importance of synthesizing pure ZnO and Co3O4 nanoparticles with composites of ZnCo2O4 (zinc cobaltite) nanorods in three various proportions (90:10, 75:25, and 50:50) is emphasized in this study. Many advanced approaches were used to assess the various features of these materials, including size and shape. Fourier transform infrared (FT-IR) spectroscopy was used to determine the vibrational modes of the materials. The absorption measurements were then carried out using UV-vis spectroscopic techniques, and the photocatalytic breakdown of MO was done under visible light irradiation. The findings revealed that pure materials were inadequate for visible light activity, resulting in decreased degradation efficiencies. Spinel cobaltite structures have potential degradation efficiency under visible light, while ZnCo2O4 (50:50) catalyst has superior degradation efficiency of 59.8% over MO. The crystallite size, morphology, functional group, absorption wavelength, and band gap all play important roles in enhancing the material's photocatalytic activity under visible light. Meanwhile, ZnCo2O4 spinel structures are crucial for increasing charge carriers and reducing electron-hole recombination. As a result, zinc cobaltite minerals are widely used in industrial dye degradation applications.

A novel n-p heterojunction Bi2S3/ZnCo2O4 photocatalyst for boosting visible-light-driven photocatalytic performance toward indigo carmine

An innovative p-n heterojunction Bi2S3/ZnCo2O4 composite was first fabricated via a two-step co-precipitation and hydrothermal method. By controlling the weight amount of Na2S and Bi(NO3)3 precursor, different heterogeneous xBi2S3/ZnCo2O4 were synthesized (x = 0, 2, 6, 12, and 20). The p-n heterojunction Bi2S3/ZnCo2O4 was characterized by structural, optical, and photochemical properties and the photocatalyst decoloration of indigo carmine. Mott-Schottky plots proved a heterojunction formed between n-Bi2S3 and p-ZnCo2O4. Furthermore, the investigation of the photocurrent response indicated that the Bi2S3/ZnCo2O4 composite displayed an enhanced response, which was respectively 4.6 and 7.3 times (4.76 μA cm-2) greater than that of the pure Bi2S3 (1.02 μA cm-2) and ZnCo2O4 (0.65 μA cm-2). Especially the optimized p-n Bi2S3/ZnCo2O4 heterojunction with 12 wt% Bi2S3 showed the highest photocatalyst efficacy of 92.1% at 40 mg L-1 solutions, a loading of 1.0 g L-1, and a pH of 6 within 90 min of visible light illumination. These studies prove that p-n Bi2S3/ZnCo2O4 heterojunction photocatalysts can greatly boost their photocatalytic performance because the inner electric field enhances the process of separating photogenerated electron-hole pairs. Furthermore, this composite catalyst showed good stability and recyclability for environmental remediation.

ZnCo2O4/g-C3N4/Cu nanocomposite as a new efficient and recyclable heterogeneous photocatalyst with enhanced photocatalytic activity towards the metronidazole degradation under the solar light irradiation

In this study, ZnCo₂O₄/g-C₃N₄/Cu is synthesized as a new and highly effectual solar light-driven heterogeneous photocatalyst. The prepared photocatalyst is characterized using FT-IR, XRD, XPS, DRS, FESEM, TEM, EDS, and elemental mapping techniques. The performance of ZnCo₂O₄/g-C₃N₄/Cu is studied towards the metronidazole (MNZ) degradation under solar light irradiation. The kinetics of MNZ degradation and efficacy of the operational parameters comprising the initial MNZ amount (10-30 mg L^-1), photocatalyst dosage (0.005-0.05 g L^-1), pH (3-11), and contact time (5-30 min) on the MNZ degradation process are investigated. Surprisingly, the ZnCo₂O₄/g-C₃N₄/Cu nanocomposite presents a privileged photocatalytic performance towards the MNZ degradation under solar light irradiation. The enhanced photocatalytic activity of this photocatalyst can be ascribed to the synergistic optical effects of ZnCo₂O₄, g-C₃N₄, and Cu. The value of band gap energy for ZnCo₂O₄/g-C₃N₄/Cu is estimated to be 2.3 eV based on the Tauc plot of (αhν)² vs. hν. The radical quenching experiments confirm that the superoxide radicals and holes are the principal active species in the photocatalytic degradation of MNZ, whereas the hydroxyl radicals have no major role in such degradation. The as-prepared photocatalyst is simply isolated and recycled for at least eight runs without noticeable loss of the efficiency. Using the natural sunlight source, applying a very low amount of the photocatalyst, neutrality of the reaction medium, short reaction time, high efficiency of the degradation procedure, utilizing air as the oxidant, low operational costs, and easy to recover and reuse of the photocatalyst are the significant highlights of the present method. It is supposed that the current investigation can be a step forward in the representation of an efficacious photocatalytic system in the treatment of a wide range of contaminated aquatic environments.

Sonochemical synthesis of ZnCo2O4/Ag3PO4 heterojunction photocatalysts for the degradation of organic pollutants and pathogens: a combined experimental and computational study

ZnCo2O4/Ag3PO4 heterostructure nanoparticles were prepared by a facile ultrasonic method and characterized by various techniques. The photocatalytic activity of ZnCo2O4/Ag3PO4 nanoparticles was investigated for the degradation of organic pollutants (methyl...