Optical and antibacterial activity of biogenic core-shell ZnO@TiO2 nanoparticles

Plant-mediated Z-scheme ZnO/TiO2-NCs for antibacterial potential and dye degradation: experimental and DFT study

Efficient separation of electron-hole pairs remains pivotal in optimizing photogenerated carrier functionality across diverse catalytic and optoelectronic systems. This study presents the fabrication of a novel hollow direct Z-scheme photocatalyst, ZnO/TiO2. A thorough analysis encompassing various techniques such as Ultraviolet-Visible Spectroscopy (UV-Vis), X-ray Diffraction (XRD), Transmission electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Energy-Dispersive X-ray Spectroscopy (EDX) provided detailed insights into the complex material characteristics of the ZnO/TiO2 heterojunction catalyst. The findings revealed coexisting anatase TiO2 and wurtzite ZnO phases, each retaining distinct attributes within the nanocomposites (NCs) structure. The study showcased the photocatalytic efficacy of ZnO/TiO2-NCs in decomposing Methylene Blue and Acridine Orange under UV irradiation, correlated with their underlying structures. Enhanced degradation of these dyes resulted from the establishment of a direct Z-scheme heterojunction between ZnO and TiO2. Employing Density Functional Theory (DFT) using Quantum ESPRESSO, this research analyzed phase diagrams and band structures, elucidating electronic properties and structural correlations. The study characterized a ZnO/TiO2 composite, revealing a band gap of 3.1-3.3 eV through UV-Visible spectroscopy and confirming its formation without impurity phases via XRD analysis. TEM and EDX showed uniform element dispersion (Zn: 27%, Ti: 29.62%, C: 5.03%, O: 38.35%). Computational analysis using DFT indicated a reduction in stable phases with increasing temperature. Enhanced dye degradation was observed (MB: 88.9%, AO: 84%), alongside significant antibacterial activity. In the future we predict that research will focus on development of scaled up production and photocatalytic activity through surface modification, while unveiling mechanistic insights and environmental applicability for multifunctional use in water treatment and antibacterial applications, leading to further advancement of the field.

Fabrication of Ternary MoS2/CdS/Bi2S3-Based Nano Composites for Photocatalytic Dye Degradation

The synthesis and design of low-cost visible-light-active catalysts for the photodegradation of organic dyes have been regarded as an efficient way to use solar energy in addressing environmental issues. We report the fabrication of MoS2/CdS nanoparticles functionalized with Bi2S3 nanoflakes. The ternary composites of “MoS2/CdS/Bi2S3” were synthesized in situ by a hydrothermal method at different temperatures. The changes in structural, optical, and morphological properties of the synthesized CdS/MoS2/Bi2S3 were explored. The effects of Bi2S3 on CdS/MoS2 were thoroughly studied by performing an X-ray diffractometer (XRD), a scanning electron microscope (SEM), an ultra-violet–visible spectrometer (Uv–vis), and Fourier transform infrared spectroscopic (FT-IR) studies of the nanoparticles. XRD confirms the cubical crystal structure of the nanoparticles. SEM studies possess the modulation in the surface morphology with the tenability in volume ratios of “MoS2/CdS/Bi2S3” composites. It was observed that the bandgaps calculated using absorption measurements could be manipulated from 2.40 eV to 0.97 eV with varying Bi2S3 in the MoS2/CdS nanostructures. FT-IR confirmed the synthesis of “MoS2/CdS/Bi2S3” nanoparticles. On allowing the visible light to fall for 120 min, it was observed that “MoS2/CdS/Bi2S3” degrades the methylene blue up to 90%. The calculated results of “MoS2/CdS/Bi2S3” suggest that the synthesized material could be a strong candidate for photodegradation applications. This research work explains the synthesis of MoS2/CdS/Bi2S3-based nanocomposites for the degradation of dye using a photocatalytic process. The final results show that this catalyst effectively degrades the dye.

Activated Carbon-Loaded Titanium Dioxide Nanoparticles and Their Photocatalytic and Antibacterial Investigations

Activated carbon doping TiO2 nanoparticles were synthesised by zapota leaf extract using the co-precipitation method. The bio-constituents of plant compounds were used in the reactions of stabilization and reductions. The carbon loading on the TiO2 nanoparticles was characterised by XRD, FTIR, UV-DRS, SEM with EDX, and TEM analysis. The loading of activated carbon onto the TiO2 nanoparticles decreased the crystallite size and optical bandgap, and their doping improved the surface structure of AC/TiO2 nanoparticles. Mesoporous/microporous instability was remodified from the activated carbon, which was visualised using SEM and TEM analysis, respectively. The photocatalytic dye degradation of Rh-B dye was degraded in TiO2 and AC/TiO2 nanoparticles under visible light irradiation. The degradation efficiencies of TiO2 and AC/TiO2 nanoparticles were 73% and 91%, respectively. The bacterial abilities of TiO2 and AC/TiO2 nanoparticles were examined by E. coli and S. aureus. The water reclamation efficiency and bactericidal effect of TiO2 and AC/TiO2 nanoparticles were examined via catalytic dye degradation and bacterial efficiency of activated carbon-doped titanium dioxide nanoparticles.