Polydopamine-Coated Fe3O4 Nanoparticles as Synergistic Redox Mediators for Catalytic Reduction of Azo Dyes

NANO ◽  
2017 ◽  
Vol 12 (03) ◽  
pp. 1750037 ◽  
Author(s):  
Sinan Du ◽  
Yang Luo ◽  
Fang Zuo ◽  
Xinhua Li ◽  
Dong Liu
Keyword(s):  
Catalytic Activity ◽  
Azo Dyes ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Chemical Reduction ◽  
Redox Mediators ◽  
Electron Transfer Mechanism ◽  
Transmission Electron ◽  
Reductive Degradation ◽  
Detailed Chemical

Polydopamine-coated Fe3O4 (Fe3O4@PDA) nanoparticles (NPs) were prepared as synergistic redox mediators for the catalytic reduction, by NaBH4, of azo dyes such as methyl orange (MO) and methyl red (MR). Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were applied to determine their surface morphology, surface chemistry and detailed chemical composition, respectively. The latter technique confirmed the presence of quinone moieties. Moreover, a vibrating sample magnetometer (VSM) was used to confirm the superparamagnetic properties of these NPs. The characteristic optical absorption maximum of MO at 462[Formula: see text]nm was used to monitor the decolorization process. This was employed to determine the catalytic activity in the reaction. An enhancement of the catalytic activity of the magnetic-separable Fe3O4@PDA nanocatalyst over that of PDA microspheres (MPs) was observed. Moreover, their reusability and stability were also investigated. A synergistic electron transfer mechanism involving both Fe3O4 and PDA moieties was proposed as follows: the quinone moieties and Fe (III) species in Fe3O4@PDA NPs served as systematic redox mediators, with quinone receiving an electron from NaBH4. The reduced quinone next transfers an electron to the Fe (III) moiety, generating an Fe (II) species that in turn transfers an electron to the azo dye. We determined that this process resulted in enhanced reductive degradation of azo dyes when compared with PDA MPs. Moreover, Fe3O4@PDA NPs could be magnetically separated and recycled. We therefore concluded that these NPs show great potential in the immobilization of homogeneous catalysts in the chemical reduction processes of azo dyes.

scholarly journals A Review on the Catalytic Hydrogenation of Bromate in Water Phase

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 365
Author(s):  
Jose Luis Cerrillo ◽  
Antonio Eduardo Palomares
Keyword(s):  
Catalytic Activity ◽  
Ion Exchange ◽  
Reaction Mechanisms ◽  
Catalytic Reduction ◽  
Environmental Concern ◽  
Chemical Reduction ◽  
Catalyst Stability ◽  
Polluted Water ◽  
Water Composition

The presence of bromate in water sources generates environmental concern due to its toxicity for humans. Diverse technologies, like membranes, ion exchange, chemical reduction, etc., can be employed to treat bromate-polluted water but they produce waste that must be treated. An alternative to these technologies can be the catalytic reduction of bromate to bromide using hydrogen as a reducing agent. In this review, we analyze the research published about this catalytic technology. Specifically, we summarize and discuss about the state of knowledge related to (1) the different metals used as catalysts for the reaction; (2) the influence of the support on the catalytic activity; (3) the characterization of the catalysts; (4) the reaction mechanisms; and (5) the influence of the water composition in the catalytic activity and in the catalyst stability. Based on published papers, we analyze the strength and weaknesses of this technique and the possibilities of using this reaction for the treatment of bromate-polluted water as a sustainable process.

scholarly journals Amino-Modified Silica as Effective Support of the Palladium Catalyst for 4-Nitroaniline Hydrogenation

Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 375
Author(s):  
Adele R. Latypova ◽  
Maxim D. Lebedev ◽  
Evgeniy V. Rumyantsev ◽  
Dmitry V. Filippov ◽  
Olga V. Lefedova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Electron Donor ◽  
Photoelectron Spectroscopy ◽  
Functionalized Silica ◽  
Amino Groups ◽  
Modified Silica ◽  
Pulse Technique ◽  
X Ray ◽  
Transmission Electron

The article describes the synthesis of aminoorgano-functionalized silica as a prospective material for catalysis application. The amino groups have electron donor properties which are valuable for the metal chemical state of palladium. Therefore, the presence of electron donor groups is important for increasing catalysts’ stability. The research is devoted to the investigation of silica amino-modified support influence on the activity and stability of palladium species in 4-nitroaniline hydrogenation process. A series of catalysts with different supports such as SiO2, SiO2-C3H6-NH2 (amino-functionalized silica), γ-Al2O3 and activated carbon were studied. The catalytic activity was studied in the hydrogenation of 4-nitroaniline to 1,4-phenylenediamine. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and chemisorption of hydrogen by the pulse technique. The 5 wt.% Pd/SiO2-C3H6-NH2 catalyst exhibited the highest catalytic activity for 4-nitroaniline hydrogenation with 100% conversion and 99% selectivity with respect to 1,4-phenylenediamine.

scholarly journals Nanosized V-Ce Oxides Supported on TiO2 as a Superior Catalyst for the Selective Catalytic Reduction of NO

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 202
Author(s):  
Long Lu ◽  
Xueman Wang ◽  
Chunhua Hu ◽  
Ying Liu ◽  
Xiongbo Chen ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Redox Capacity ◽  
Scr Of No ◽  
Temperature Programmed

Nanosized V-Ce oxides supported on TiO2 (VCT) were prepared and utilized in the low-temperature selective catalytic reduction (SCR) of NO with NH3. Compared with the other V-Ce oxides-based catalysts supported on Al2O3, ZrO2, and ZSM-5, VCT showed the best SCR activity in a low-temperature range. The NOx conversion of 90% could be achieved at 220 °C. Characterizations including X-ray diffraction (XRD), scanning election micrograph (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption with NH3 (NH3-TPD), and temperature-programmed reduction with H2 (H2-TPR) showed that V1.05Ce1/TiO2 exhibited a good dispersion of V2O5, enrichment of surface Ce3+ and chemical-absorbed oxygen, and excellent redox capacity and acidity, which resulted in the best SCR performance at low temperature.

Electrooxidation of Methanol on Carbon Supported Gold Nanoparticles

2013 ◽  
Vol 313-314 ◽  
pp. 232-236
Author(s):  
Dan Zhang
Keyword(s):  
Gold Nanoparticles ◽  
Catalytic Activity ◽  
Competitive Adsorption ◽  
Chemical Reduction ◽  
Reduction Process ◽  
Carbon Support ◽  
Transmission Electron ◽  
Supported Gold Nanoparticles ◽  
Supported Gold

Activated carbon supported gold nanoparticles (Au/C) were prepared by a chemical reduction process using NaBH4as a reducing agent. The characterization of transmission electron microscope indicated that the Au nanoparticles (AuNPs) in the Au/C catalyst were highly well dispersed on the carbon support. The catalytic activity of the Au/C catalyst for the methanol electrooxidation (MEO) was investigated by the cyclic voltammetry (CV). The results displayed that the Au/C catalyst exhibited a favorable catalytic activity towards the MEO in alkaline solution. Moreover, the competitive adsorption between OH-and CH3OH on the surface of the AuNPs in the Au/C catalyst existed in the course of the MEO. Based on this competitive adsorption, the mechanism of the MEO on the Au/C catalyst was further investigated.

scholarly journals Optimization of sol-immobilized bimetallic Au–Pd/TiO 2 catalysts: reduction of 4-nitrophenol to 4-aminophenol for wastewater remediation

2020 ◽  
Vol 378 (2176) ◽  
pp. 20200057
Author(s):  
Khaled Alshammari ◽  
Yubiao Niu ◽  
Richard E. Palmer ◽  
Nikolaos Dimitratos
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Reducing Agent ◽  
Wastewater Remediation ◽  
X Ray ◽  
Molar Ratios ◽  
Highly Active ◽  
Transmission Electron ◽  
Complementary Techniques

A sol-immobilization method is used to synthesize a series of highly active and stable Au x Pd 1− x /TiO 2 catalysts (where x  = 0, 0.13, 0.25, 0.5, 0.75, 0.87 and 1) for wastewater remediation. The catalytic performance of the materials was evaluated for the catalytic reduction of 4-nitrophenol, a model wastewater contaminant, using NaBH 4 as the reducing agent under mild reaction conditions. Reaction parameters such as substrate/metal and substrate/reducing agent molar ratios, reaction temperature and stirring rate were investigated. Structure-activity correlations were studied using a number of complementary techniques including X-ray powder diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. The sol-immobilization route provides very small Au–Pd alloyed nanoparticles, with the highest catalytic performance shown by the Au 0.5 Pd 0.5 /TiO 2 catalyst. This article is part of a discussion meeting issue ‘Science to enable the circular economy’.

scholarly journals Новые гетерогенные наноструктурные катализаторы на основе наночастиц переходных металлов и гексагонального нитрида бора

2021 ◽  
Vol 47 (16) ◽  
pp. 10
Author(s):  
А.С. Конопацкий ◽  
К.Л. Фаерштейн ◽  
И.Н. Волков ◽  
Д.В. Лейбо ◽  
В.В. Калинина ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Thermal Activation ◽  
Fept Nanoparticles ◽  
The Novel ◽  
Surface Chemical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Co Conversion

Structure and catalytic activity of the novel heterostructured FePt/h-BN nanomaterials in carbon monoxide oxidation reaction were studied. Transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction methods were used for structure and surface chemical composition investigation. Developed materials were demonstrated to have enhanced catalytic activity with 100% CO conversion at 250 °C. Structure ordering in FePt nanoparticles was observed during thermal activation of the material.

scholarly journals SYNTHESIS OF Ag2O/CNTs NANOCOMPOSITE TO BE USED AS A CATHODE MATERIAL FOR ZINC - SILVER BATTERIES

2018 ◽  
Vol 56 (2A) ◽  
pp. 149-155
Author(s):  
Nguyen Van Tu
Keyword(s):  
Cathode Material ◽  
Photoelectron Spectroscopy ◽  
Chemical Reduction ◽  
Specific Capacity ◽  
X Ray Diffraction ◽  
Interpenetrating Network ◽  
High Specific Capacity ◽  
X Ray ◽  
Transmission Electron ◽  
Good Cycling Stability

In this article, Ag2O/carbon nanotubes (CNTs) nanocomposite has been prepared by chemical reduction method and used as a cathode material for zinc-silver batteries. The transmission electron microscopy (TEM) tests reveal the CNTs and Ag2O nanotubes form an interpenetrating network structure. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the Ag2O shows Cubic (Pn-3) crystal structure and mixture element states in the nanocomposite. The charging/discharging property of the Ag2O/CNTs nanocomposite was studied by galvanostatic charge-discharge measurement as a cathode material. The results indicated that Ag2O/CNTs nanocomposite has high specific capacity and good cycling stability. For the current density of 0.53 mA/cm2 (2.5C), the initial specific capacity of the nanocomposite is 190 mAh/g and remains 172 mAh/g after 20 cycles. 

scholarly journals Catalytic Activity of Mixed Al2O3-ZrO2 Oxides for Glucose Conversion into 5-Hydroxymethylfurfural

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 878 ◽  
Author(s):  
Benjamín Torres-Olea ◽  
Sandra Mérida-Morales ◽  
Cristina García-Sancho ◽  
Juan Antonio Cecilia ◽  
Pedro Maireles-Torres
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Molar Ratio ◽  
X Ray ◽  
Zirconium Oxides ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Secondary Reactions ◽  
Temperature Programmed ◽  
Adsorption Desorption

In the present work, a series of catalysts based on aluminum and zirconium oxides was studied for the transformation of glucose into 5-hydroxymethylfurfural. These catalysts were characterized by using experimental techniques, such as X-ray diffraction, N2 adsorption–desorption at −196 °C, X-ray photoelectron spectroscopy, temperature-programmed desorption of NH3 and CO2, and scanning transmission electron microscopy. The catalytic behavior in glucose dehydration was evaluated in a water-methyl isobutyl ketone biphasic system, in the presence of CaCl2, in order to minimize losses due to unwanted secondary reactions. High glucose conversion and 5-hydroxymethylfurfural (HMF) yield values were obtained in the presence of an Al(Zr)Ox catalyst with an Al:Zr molar ratio of 7:3, reaching 97% and 47%, respectively, at 150 °C after 120 min. Under tested conditions, this catalyst retained most of its catalytic activity for four reuses.

scholarly journals Covalent Functionalization of Nanodiamonds by Ruthenium Porphyrin, and Their Catalytic Activity in the Cyclopropanation Reaction of Olefins

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 666
Author(s):  
Chiara Lorecchio ◽  
Emanuela Tamburri ◽  
Laura Lazzarini ◽  
Silvia Orlanducci ◽  
Robertino Zanoni ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Covalent Functionalization ◽  
X Ray ◽  
Transmission Electron ◽  
Ruthenium Porphyrin ◽  
Scanning Electron

Detonation nanodiamonds (DNDs) were functionalized by ruthenium porphyrins and used as catalysts in the cyclopropanation reaction of olefins. The heterogeneous catalyst was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and XPS (X-ray photoelectron spectroscopy). The XPS was used to control the binding of the ruthenium porphyrin to the DNDs’ surface. This catalyst was used in the cyclopropanation reactions of simple olefins and was reused with no loss of activity in four consecutive cycles, after recovering each time by simple centrifugation.

scholarly journals Effect of Direct Reduction Treatment on Pt–Sn/Al2O3 Catalyst for Propane Dehydrogenation

Catalysts ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 446 ◽  
Author(s):  
Jae-Won Jung ◽  
Won-Il Kim ◽  
Jeong-Rang Kim ◽  
Kyeongseok Oh ◽  
Hyoung Lim Koh
Keyword(s):  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Direct Reduction ◽  
Coke Formation ◽  
Catalytic Performance ◽  
Propane Dehydrogenation ◽  
X Ray ◽  
Transmission Electron ◽  
Calcination Step ◽  
Xrd Patterns

Pt–Sn/Al2O3 catalysts were prepared by the direct reduction method at temperatures from 450 to 900 °C, denoted as an SR series (SR450 to SR900 according to reduction temperature). Direct reduction was performed immediately after catalyst drying without a calcination step. The activity of SR catalysts and a conventionally prepared (Cal600) catalyst were compared to evaluate its effect on direct reduction. Among the SR catalysts, SR550 showed overall higher conversion of propane and propylene selectivity than Cal600. The nano-sized dispersion of metals on SR550 was verified by transmission electron microscopy (TEM) observation. The phases of the bimetallic Pt–Sn alloys were examined by X-ray diffraction, TEM, and energy dispersive X-ray spectroscopy (EDS). Two characteristic peaks of Pt3Sn and PtSn alloys were observed in the XRD patterns, and these phases affected the catalytic performance. Moreover, EDS confirmed the formation of Pt3Sn and PtSn alloys on the catalyst surface. In terms of catalytic activity, the Pt3Sn alloy showed better performance than the PtSn alloy. Relationships between the intermetallic interactions and catalytic activity were investigated using X-ray photoelectron spectroscopy. Furthermore, qualitative analysis of coke formation was conducted after propane dehydrogenation using differential thermal analysis.

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