Search

Porous cerium oxide (ceria) nanoparticles were prepared with and without manganese (Mn) by using the flash combustion technique. Samples with different loadings (Ce/Mn ratio ranged from 100 to 10) were prepared by using a one-step process and water only as a solvent. Moreover, citric acid was utilized as a fuel in an aqueous medium, and the overall synthesis mixture was dried at 100 °C overnight and then calcinated at 550 °C for 3 h. The obtained final solid product was characterized by inductively coupled plasma (ICP), X-ray powder diffraction (XRD), diffuse reflectance ultraviolet-visible spectroscopy (DR-UV-Vis), and scanning electron microscopy (SEM), which was coupled with Energy Dispersive X-Ray Analysis (EDX), high resolution transmission electron microscopy (HR-TEM), and photoluminescence (PL) analysis. The characterization data showed that Mn ions were totally incorporated into the framework of ceria up to the applied loading. Under visible light illumination, the photocatalytic activity of the prepared samples was tested in the decolorization reaction of methyl green (MG) dye (wavelength greater than 425 nm). The results showed that increasing Mn content improved the photocatalytic activity of ceria. The sample with a Ce/Mn ratio of 10 performed 1.8 times better than bare porous ceria. Finally, the reusability of the best-performing sample was investigated in four consecutive runs without treatment, and slight deactivation was monitored after the fourth run. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report on C-dots derived from beetroot and Fabrication of 0D/0D C-dots@CdS heterostructured photocatalysts. • C-dots@CdS showed superior activity with H 2 evolution rates of 1582 µmolg−1 than the pristine CdS (849 µmolg−1). • Achieved 97.3 % degradation efficiency of CV dye under visible light for C-dots@CdS. • The presence of C-dots in heterojunction increases the charge carrier separation leading to highest photocatalytic activity. Carbon dots (C-dots) developed from beetroot is used for the rational design of cadmium sulphide based heterojunction photocatalysts (C-dots@CdS) using hydrothermal technique. The crystal structure, phase, morphology and optical characteristics of the synthesised materials are determined using X-ray diffraction (XRD), High resolution transmission electron microscopy (HR-TEM), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV–Visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL spectroscopy), BET adsorption, X-ray photoelectron spectroscopy (XPS) and electrochemical studies. Using C-dots@CdS catalytic system, a superior photocatalytic activity relative to the undecorated CdS is observed. Among the C-dots@CdS samples, the CdS loaded with 6 wt% of C-dots exhibited enhanced hydrogen evolution rate compared with other samples considered for the study. CdS nanospheres modified with C-dots (6 wt%) resulted in the photocatalytic hydrogen evolution rate of 1582 µmolg−1 against 849 µmolg−1 evolution rate obtained for CdS nanospheres within 3 h. In spite of being 0D/0D type nano-heteroarchitecture, C-dots@CdS system obtained an apparent quantum yield of 6.37 % for the catalytic dosage of 20 mg under the irradiation of visible light. CdS in the C-dots@CdS system serves as the light harvester while C-dots with discernible edges can maintain the continuous supply of photo-excited charge carriers and hence can reduce the charge-carrier recombination. Further, the photodegradation of crystal violet dye using the optimised dosage of C-dots@CdS-6 exhibited an efficiency of 97.3 % in 120 min of visible light irradiation under neutral conditions. The detailed kinetic study reveals that the mechanism of photodegradation of crystal violet dye using C-dots@CdS system can be described using pseudo-second-order kinetics. The presence of oxygen rich hydrophilic surface functionalities of C-dots, the formation of near-surface heterojunction and the suitable band structure of C-dots@CdS system leading to the optimum charge carrier separation kinetics can be attributed to the enhanced photocatalytic performance. This work offers a promising strategy to develop bio-derived C-dots based heterojunction photocatalyst to address the burgeoning energy and environmental demands. [ABSTRACT FROM AUTHOR]

• A cheaper synthesis and structural analysis of catalyst to degrade dye is reported. • pH-dependent catalytic activity of CoFe 2 O 4 for cationic & anionic dyes degradation. • Charges on CoFe 2 O 4 were determined by zetapotential evaluation during DLS studies. • A correlation between charges of nanoparticle and dyes molecules in catalysis. This work reports the application of non-functionalized cobalt ferrite (CF) magnetic nanoparticles (MNPs) as a fast dye removing agent. Herein, we have synthesized the CF MNPs by chemical co-precipitation method. The photocatalytic activity is demonstrated with examples of cationic and anionic dyes depending on different pH. The synthesized CF MNPs were characterized by X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDAX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), selected area electron diffraction (SAED), vibrating sample magnetometer (VSM) and Brunauer-Emmett-Teller measurement (BET) to confirm the structural, morphological, magnetic property and surface area. We have shown its high efficiency in removal of both types of ionic dyes with moderate first order reaction rate under different pH. Because of its magnetic property it is easy to separate from the reaction mixture by magnetic separation method after its use, which is an added advantage in case of recycling. From the application point of view, these MNPs may be useful in promising industrial usage purpose because of its high stability, fast dye removal efficiency and low-cost. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present work, CaWO 4 /Ag 2 MoO 4 nanohybrid was synthesized by sono-chemical method. Fourier-transform infrared spectroscopy (FTIR), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDAX) and BET surface area analyzer were used to characterize the structure and optical properties of CaWO 4 /Ag 2 MoO 4 nanohybrid. The HRTEM image represents the formation of CaWO 4 /Ag 2 MoO 4 nanohybrid with clear facets and narrow size range. The XRD results showed that CaWO 4 /Ag 2 MoO 4 nanohybrid composed of combined phases of CaWO 4 and Ag 2 MoO 4. A red-shift was observed in the optical absorption of nanohybrid after loading Ag 2 MoO 4 on CaWO 4. The photodegradation of MB by CaWO 4 /Ag 2 MoO 4 nanohybrid (91.4%) showed excellent performance when compared with the pure Ag 2 MoO 4 (59.6%) and CaWO 4 (14.3%) under visible light. The scavenging test revealed that the key species responsible for the degradation of MB dye was hydroxide radical (•OH). The degradation of MB was well fitted to the pseudo-first-order kinetics with a high regression coefficient value (R2 > 0.95). The photostability and reusability of the nanohybrid was studied and the nanohybrid showed almost same degradation efficiency even at 6th cycle. The nanohybrid showed enhanced antimicrobial activity against Escherichia coli and Bacillus subtilis. Therefore, CaWO 4 /Ag 2 MoO 4 nanohybrid photocatalyst can be used as an effective candidate for environmental remediation through photocatalysis and bactericidal applications. • CaWO 4 /Ag 2 MoO 4 nanohybrid was synthesized by sonochemical method. • The CaWO 4 /Ag 2 MoO 4 nanohybrid can able to degrade 91.4% of MB dye in 180 min. • CaWO 4 /Ag 2 MoO 4 nanohybrid demonstrates good photocatalytic activity, photostability and antimicrobial activity. • The active species of photocatalytic activity of nanohybrid was due to the photogenerated hydroxide radicals. [ABSTRACT FROM AUTHOR]

This work investigates the degradation of the azo dye solochrome dark blue (SDB) by measurement of the photocatalytic, sonocatalytic and sonophotocatalytic activities, under low ultrasonic frequency (40 kHz) and UV-C (254 nm) light, using Mn-doped ZnS semiconductor quantum dots (Mn2+:ZnS Qds) as catalysts, prepared by a simple chemical precipitation procedure. In order to study the different morphological and optical crystal properties, various characterization techniques were used, such as high resolution transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, N2 adsorption-desorption at −196 °C and ultraviolet-visible spectroscopy. The average particle size of the semiconductor Qds was in the range of 3–4 nm. The optimal parameters affecting dye degradation, such as the catalyst loading, solution pH, time of irradiation, initial concentration of dye, dopant concentration, ultrasonic power and frequency effect were evaluated. The synthesized catalytic material exhibited a high activity for sonophotocatalytic degradation of SDB (89%), larger than that observed for sonocatalysis (69.7%) or photocatalysis (55.2%) alone, which was due to the improved electron-holes separation, formation of more reactive radicals and enhancement of the active surface area. Qds showed good stability and reusability after five repeated cycles. Finally, the degradation products were identified by liquid chromatography-mass spectrometry (LC-MS). [ABSTRACT FROM AUTHOR]