Morphologically Controllable Hierarchical ZnO Microspheres Catalyst and Its Photocatalytic Activity

The degradation of pollutants in wastewater using abundant resources and renewable energy sources, such as light, is attractive from an environmental perspective. ZnO is a well-known photocatalytic material. Therefore, in this study, a hierarchical ZnO microsphere precursor was prepared using a hydrothermal method. The precursor was subsequently annealed at different temperatures, which enabled the production of a ZnO catalyst having a controllable morphology. Specifically, as the annealing temperature increased, the precursor crystallized into hexagonal wurtzite and the crystallinity also increased. The catalysts were tested for their photocatalytic activity for the degradation of dye molecules (methylene blue and rhodamine B), and the catalyst sample annealed at 400 °C showed the best photocatalytic activity. The origin of this activity was studied using electron paramagnetic resonance spectroscopy and transient photocurrent measurements, and the structure of the optimal catalyst was invested using electron microscopy measurements, which revealed that it was formed of two-dimensional nanosheets having smooth surfaces, forming a 2D cellular network. Thus, we have presented a promising photocatalyst for the mineralization of organic contaminants in wastewater.

Batch Preparation of CuO/ZnO-Loaded Nanofiber Membranes for Photocatalytic Degradation of Organic Dyes

Composite nanofiber membranes (CNFMs) loaded with CuO/ZnO (CZCNFMs) have important applications in a series of organic and industrial catalytic reactions because of nanoeffects of the nanofibers and the peculiar performances of semiconductor oxides. In this work, CZCNFMs with different mass ratios of Cu to Zn were successfully fabricated in batches using modified bubble electrospinning (MBE), a heat treatment method, and a hydrothermal method. The influences of the mass ratio of Cu to Zn on the morphologies, structures, and properties of the CNFMs were studied, and the obtained CNFMs with different mass ratios of Cu to Zn were applied to the photodegradation of methyl orange (MO) and methylene blue (MB). The results showed that when the mass ratio of Cu to Zn was 5:5, the fabricated CNFM had better morphology, structure, and mechanical properties and had the best degradation effects on MO and MB. In addition, the principal active substances produced during the photodegradation of MO were defined by free radical capture experiments, and the influences of the pH value of the MO solution on the photocatalytic activity of the CNFMs with the optimal mass ratio of 5:5 were discussed.

Influence of metallic species for efficient photocatalytic water disinfection: bactericidal mechanism of in vitro results using docking simulation

TiO₂-based heterogeneous photocatalysis systems have been reported with remarkable efficiency to decontaminate and mineralize a range of pollutants present in air and water medium. In the present study, a series of visible light active metal oxide TiO₂ nanoparticle were synthesized and evaluated for their photodegradation efficiency against emerging textile pollutant (Reactive Yellow 145) and antibacterial applications. In the first phase, nanomaterial synthesis was carried out following various synthesis parameters like addition of metallic impurities (different types and concentration) and calcination temperature. In the second phase, synthesized nanomaterials were screened for their performance in terms of photocatalytic degradation of RY145 and the best one (Fe-1-T-3 with 100% RY145 removal within 80 min of irradiation) was further optimized against various reaction parameters. To get knowledge about the insights of nanomaterial performance for degradation of different environmental pollutants, the most important is to understand their physicochemical properties utilizing different characterization techniques. The physical morphology and elemental dispersion of metal-doped TiO₂ nanomaterials were analyzed and results indicated that added metallic impurities were well dispersed onto the substrate surface. The efficient nanomaterials selected from initial screening were further assessed for photocatalytic disinfection efficiency against human pathogenic bacterial strains. Antimicrobial activities of the metal oxide nanomaterial were tested against gram-positive and gram-negative pathogenic bacterial strains. Possible mode of interaction of nanomaterial with bacterial DNA for bacterial cell inactivation was predicted using molecular docking simulation. The research project has the potential to contribute to multiple disciplines like material synthesis, water disinfection, and as green solutions for the textile industry replacing traditional technologies.