Enhanced photocatalytic activity of plasmonic Au nanoparticles incorporated MoS2 nanosheets for degradation of organic dyes

In this paper, nanocomposite NiO/Cr2O3 has been synthesized by a simple chemical reduction method to study its photocatalytic activity under sunlight irradiation. Various advanced analytical techniques including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), elemental mapping, Fourier transform infrared spectroscopy (FTIR), and UV-visible spectroscopy have been utilized to characterize the synthesized NiO/Cr2O3 nanocomposite. SEM images show the sheet-shaped morphology of NiO/Cr2O3 nanocomposite. These sheets have a rough surface with nano to micro size cracks. These cracks play important role in the enhancement of photocatalytic activity by increasing surface active sites for the adsorption of dye molecules on the surface of the photocatalyst. The organic dyes crystal violet (CV) and methylene blue (MB) have been chosen to study the photocatalytic behavior of NiO/Cr2O3 nanocomposite under sunlight irradiation. The photocatalytic efficiency of NiO/Cr2O3 nanocomposite has been obtained 88.47% and 93.63% against crystal violet and methylene blue respectively. The results of the photocatalytic kinetics exhibit that degradation rate constant value for crystal violet dye is higher as compared to methylene blue dye. Obtained kinetic results indicate that synthesized nanocomposite acts as an efficient photocatalyst for the degradation of both crystal violet dye and methylene blue dye. NiO/Cr2O3 nanocomposite also exhibited reusability and stability for photocatalytic degradation of both organic dyes. Photoelectrochemical measurements as photocurrent, electrochemical impedance spectroscopy (EIS), and Mott-Schottky plot were also performed for synthesized NiO/Cr2O3 nanocomposite. Consequently, this synthesized NiO/Cr2O3 nanocomposite can be utilized for environmental remediation of harmful dyes.

Template-free growth of well-crystalline α-Fe2O3 nanopeanuts with enhanced visible-light driven photocatalytic properties

10 - A facile biogenic-mediated synthesis of Ag nanoparticles over anchored ZnO for enhanced photocatalytic degradation of organic dyes

Semiconducting nanomaterials based heterogeneous photocatalysis represent a low-cost, versatile technique for environmental remediation, including pollution mitigation, energy management and other environmental aspects. Herein, we demonstrate the syntheses of various heterogeneous photocatalysts based on highly reduced graphene oxide (HRG) and vanadium oxide (VOx)-based nanocomposites (HRG–VOx). Different shapes (rod, sheet and urchin forms) of VOx nanoparticles were successfully fabricated on the surface of HRG under solvo-/hydrothermal conditions by varying the amount of water and ethanol. The high concentration of water in the mixture resulted in the formation of rod-shaped VOx nanoparticles, whereas increasing the amount of ethanol led to the production of VOx sheets. The solvothermal condition using pure ethanol as solvent produced VOx nano-urchins on the surface of HRG. The as-prepared hybrid materials were characterized using various spectroscopic and microscopic techniques, including X-ray diffraction, UV–vis, FTIR, SEM and TEM analyses. The photocatalytic activities of different HRG–VOx nanocomposites were investigated for the photodegradation of methylene blue (MB) and methyl orange (MO). The experimental data revealed that all HRG–VOx composite-based photocatalysts demonstrated excellent performance toward the photocatalytic degradation of the organic dyes. Among all photocatalysts studied, the HRG–VOx nanocomposite consisting of urchin-shaped VOx nanoparticles (HRG–VOx-U) demonstrated superior photocatalytic properties towards the degradation of dyes.

Efficient adsorption and facile photocatalytic degradation of organic dyes over H-bonded proton-transfer complex: An experimental and theoretical approach

Various types of organic dyes are discharged by textile/batik industry daily. These are the problematic issues for water treatment system based on semiconductor photocatalysts as various types of organic dyes could degrade differently due to different in molecular nature. In this study, the photocatalytic activity of TiO2 particles in degradation of various types of organic dyes, i.e. methylene blue (MB), rhodamine B (RhB) and bromocresol green (BG) dyes, under visible light and UV light irradiation were systematically studied. The crystal structure and morphology of TiO2 particles were analyzed by X-ray Diffraction Spectroscopy and Field-emission Scanning Electron Microscope, respectively. The average diameter of Rutile-TiO2 was 92 ± 39 nm. The degradation of organic dyes was monitored from its maximum absorption peak measured by ultra violet-visible spectrophotometer. Under UV light irradiation, high degradation efficiencies of dyes were observed and followed the order of: RhB > MB > BG, indicating that the dyes were mineralized by photogenerated hydroxyl free radicals and/or superoxide free radicals. Under visible light irradiation, the photodegradation efficiencies followed the order of: MB > RhB > BG. As compared to UV light, the degradation of organic dyes were different in visible light which relied on the electrons ejected from dye molecules upon absorbing light energy.

Background: Seaweeds, being abundant sources of active components have attained much interest in recent times. The seaweeds are routinely used in life science research and are well known for their biological applications. In addition to that, the synthesis of metallic nanoparticles from these natural resources has its own attraction in drug delivery and was observed by using 2 mL of Ag NP colloids. Objective: In this study, the synthesis of silver nanoparticles (Ag NPs) using Padina tetrastromatica has been evaluated for their catalytic activity in the degradation of organic dye. Method: The catalytic activity of the biosynthesized Ag NP colloid was studied for the degradation of Methylene blue (MB) and Acridine orange (AO) dye. The degradation of methylene blue and acridine orange was observed at regular time interval by using UV-vis absorption spectra at 664 nm and 490 nm respectively. Results: The percentage of dye degradation increased in the presence of NaBH4. It was observed that 80.09% of MB dye reduction was observed by using 2 mL of Ag NP colloids. The acridine orange dye showed reduction of 83.06%. The rate constants for the reduction of Methylene blue (MB) and acridine orange (AO) dye using 2 mL Ag NPs colloids are 0.077 and 0.090 min-1, respectively.

Cobalt aluminate/carbon composite nanoparticles have been synthesised by utilising an auto-combustion method using glycine as an inexpensive fuel. The products were analysed by various techniques such as powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermal analysis (TG), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectrum (DRS), energy-dispersive X-ray spectroscopy (EDS). The results exhibited that the average crystallite size of the as-prepared CoAl2O4/C nanocomposite was ca. 26 nm. The photocatalytic activity of the as-prepared catalyst was evaluated through the degradation of methylene blue (MB) dye under different conditions, and the photocatalytic degradation mechanism was proposed. The results indicated that CoAl2O4/C nanocomposite has a high catalytic performance for the photocatalytic degradation of MB dye under UV illumination in the presence of H2O2. The degradation efficiency reached 98.5% in 90 min with a degradation rate constant of 0.046 min−1.

Complementary metalloporphyrin-based nanostructure decorated with silver nanoparticles for photocatalytic degradation of organic dyes

Herein, preparation of novel multimetallic core–satellite Pt‐nanodots decorated TiO2‐coated AuNPs (AuNPs@TiO2@Pt) plasmonic nanoparticles with well‐defined spherical dendritic morphology and excellent colloidal stability are reported. The coating of a TiO2 layer and PtNDs maximizes the surface plasmon resonance as there is a redshift from 525 to 550 nm and also increases surface area significantly. Prepared plasmonic nanohybrid is tested for multiple photosystems such as water pollutants (methylene blue, methyl orange, and methyl red) photodegradation at room temperature in visible light irradiation, and photothermal studies in near‐infrared (NIR, 808 nm) light. AuNPs@TiO2@Pt shows complete photocatalytic degradation of organic dyes (methylene blue = 40 min, methyl orange = 75 min, and methyl red = 60 min) at room temperature and the pseudo first‐order rate constant is found to be 0.1242, 0.047, and 0.068 min−1 for methylene blue, methyl orange, and methyl red degradation, respectively. Moreover, AuNPs@TiO2@Pt also shows a high photothermal effect in NIR light irradiation with an excellent morphological and photostability.

ZnO doped SnO2 nanoparticles heterojunction photo-catalyst for environmental remediation

Photocatalytic degradation of organic dye and phytohormone by a Cu(II) complex powder catalyst with added H2O2

In this study, BiFeO 3 was modified with MIL‐88 to synthesize a novel heterojunction nanocomposite MIL‐88@BiFeO 3 using solvothermal method as a photocatalyst to accelerate the methylene blue (MB) dye degradation. The catalyst was investigated by X‐ray diffraction patterns (XRD), Fourier transform infrared (FT‐IR), energy dispersive X‐ray (EDX) analysis, and scanning electron microscopy (SEM). Detailed structural and microstructural characteristics indicate the fabrication of a heterojunction nanocomposite made up of BiFeO 3 nanoparticles and MIL‐88 nanorods. Using UV–visible spectroscopy, the sample's photocatalytic efficiency for the MB dye degradation was examined under solar light. The MIL‐88@BiFeO 3 heterojunction nanocomposite exhibits superior photocatalytic activity compared to pure MIL‐88 and BiFeO 3 , with a degradation rate of 82% after 60 min of exposure to solar light. The improved photocatalytic efficiency is further supported by MIL‐88@BiFeO 3 's greatest rate constant ( k = 0.01964 min −1 ). In the as‐synthesized MIL‐88@BiFeO 3 nanocomposite, the MIL‐88 framework and BiFeO 3 might function as effective oxidation and reduction sites, releasing non‐toxic byproducts for the mineralization of MB dye, such as superoxide (O 2 •− ) and hydroxyl (•OH) species. The dye system adopted a pseudo‐first‐order model based on degradation kinetics, and the Langmuir–Hinshelwood mechanism strongly supports this model. The synergistic interaction between MIL‐88 and BiFeO 3 explains the increased efficiency of MIL‐88@BiFeO 3 .

In this work, an efficient photocatalyst based on gamma-cyclodextrin-modified titanium dioxide nanoparticles (TiO2/γ-CD NPs) was synthesized and used for photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB). The results of FESEM, EDX, TEM, FT-IR, XRD and BET surface area measurement showed that the TiO2 NPs were effectively modified with γ-CD. The photocatalytic properties of the TiO2/γ-CD NPs were evaluated by the degradation of some organic dyes in aqueous solution under ultraviolet (UV) light illumination. The experimental results confirmed that the TiO2/γ-CD had exhibited efficient photocatalytic activities higher than that of the pure TiO2 in the degradation of investigated dyes. The γ-CD could increase the lifetime of the excited states of the unreactive guests and facilitate electron transfer from the excited dye to TiO2 conduction band. The results indicated that the first-order kinetic model well describes the degradation of the dyes by TiO2/γ-CD NPs. the photocatalytic reaction rate constants for RhB, MO and MB dyes in the presence of TiO2/γ-CD NPs were 4, 5.6 and 4.2 times higher than that of pure TiO2, respectively. In addition, the TiO2/γ-CD NPs can be used for several times in real application as an effective photocatalyst.

Comparative study on the mechanism in photocatalytic degradation of different-type organic dyes on SnS2 and CdS