scholarly journals Photocatalytic Activity of Magnetic Nano-β-FeOOH/Fe3O4/Biochar Composites for the Enhanced Degradation of Methyl Orange Under Visible Light

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 526
Author(s):  
Zheng Zhang ◽  
Guanghua Wang ◽  
Wenbing Li ◽  
Lidong Zhang ◽  
Benwei Guo ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Methyl Orange ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Azo Dye ◽  
Photocatalytic Performance ◽  
Active Species ◽  
Step Method ◽  
Vis Spectroscopy

A novel nano-β-FeOOH/Fe3O4/biochar composite with enhanced photocatalytic performance and superparamagnetism was successfully fabricated via an environmentally friendly one-step method. The structural properties of the prepared composite were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and a vibrating sample magnetometer. The XPS spectrum of the as-prepared composites confirmed the presence of Fe-O-C bonds between β-FeOOH and biochar, which could be conducive to transfer photo-generated electrons. UV-vis spectroscopy confirmed the existence of an electron–hole connection between β-FeOOH and biochar, which promoted the rapid interface transfer of photogenerated electrons from β-FeOOH to biochar. These novel structures could enhance the response of biochar to accelerate the photoelectrons under visible light for more free radicals. Electron spin resonance analysis and free radical quenching experiments showed that •OH was the primary active species in the photodegradation process of methyl orange by nano-β-FeOOH/Fe3O4/biochar. In the synergistic photocatalytic system, β-FeOOH/Fe3O4/biochar exhibited excellent catalytic activity for the degradation of azo dye (methyl orange), which is 2.03 times higher than that of the original biochar, while the surface area decreased from 1424.82 to 790.66 m2·g−1. Furthermore, β-FeOOH/Fe3O4/biochar maintained a stable structure and at least 98% catalytic activity after reuse, and it was easy to separate due to its superparamagnetism. This work highlights the enhanced photocatalytic performance of β-FeOOH/Fe3O4/biochar material, which can be used in azo dye wastewater treatment.

scholarly journals Photocatalytic performance of Ag2S/ZnO/ZnS nanocomposites with high visible light response prepared via microwave-assisted hydrothermal two-step method

2018 ◽  
Vol 78 (8) ◽  
pp. 1802-1811 ◽  
Author(s):  
Jiwei Huang ◽  
Changlong Yang ◽  
Qiang Song ◽  
Dongxue Liu ◽  
Li Li
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Light Response ◽  
Light Sources ◽  
Step Method ◽  
X Ray ◽  
Microwave Assisted ◽  
Visible Light Response

Abstract A series of different ratios of Ag2S/ZnO/ZnS nanocomposites with visible light response were prepared by a microwave-assisted hydrothermal two-step method, whose composition, crystalline structure, morphology and surface physicochemical properties were well-characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis/DRS), photoluminescence spectrum (PL), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and N2 adsorption–desorption measurements. Results showed that as-composites mainly consisted of ZnS crystal phase, whose grain size increased obviously compared with non Ag2S samples. At the same time, due to the introduction of narrow band gap Ag2S, the synthesized composite can effectively increase the visible optical absorption of ZnO/ZnS composites. Among them, 1% Ag2S/ZnO/ZnS showed a mixed structure of nano-line and nano-particle, of which BET value increased significantly, and the morphology was more excellent. Photocatalytic activities of a series of Ag2S/ZnO/ZnS composites under different light sources were studied using methyl orange as a model molecule, and 1% Ag2S/ZnO/ZnS was taken as the best one. Meanwhile, 1% Ag2S/ZnO/ZnS also showed a good degradation effect on other dyes with different structures, and its degradation efficiency did not change significantly after three cycles, showing certain stability. In addition, composites with Ag2S loading of 1% possessed the highest hydrogen production ability of photolysis water, indicating that the introduction of Ag2S had significantly enhanced the catalytic performance.

scholarly journals A Facile Method for Preparing UiO-66 Encapsulated Ru Catalyst and its Application in Plasma-Assisted CO2 Methanation

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1432 ◽  
Author(s):  
Weiwei Xu ◽  
Mengyue Dong ◽  
Lanbo Di ◽  
Xiuling Zhang
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Gas Flow ◽  
Structural Integrity ◽  
Metal Organic Framework ◽  
Step Method ◽  
Co2 Methanation ◽  
X Ray ◽  
Metal Organic

With increasing applications of metal-organic frameworks (MOFs) in the field of gas separation and catalysis, the preparation and performance research of encapsulating metal nanoparticles (NPs) into MOFs (M@MOF) have attracted extensive attention recently. Herein, an Ru@UiO-66 catalyst is prepared by a one-step method. Ru NPs are encapsulated in situ in the UiO-66 skeleton structure during the synthesis of UiO-66 metal-organic framework via a solvothermal method, and its catalytic activity for CO2 methanation with the synergy of cold plasma is studied. The crystallinity and structural integrity of UiO-66 is maintained after encapsulating Ru NPs according to the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). As illustrated by X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HRTEM), and mapping analysis, the Ru species of the hydration ruthenium trichloride precursor are reduced to metallic Ru NPs without additional reducing processes during the synthesis of Ru@UiO-66, and the Ru NPs are uniformly distributed inside the Ru@UiO-66. Thermogravimetric analysis (TGA) and N2 sorption analysis show that the specific surface area and thermal stability of Ru@UiO-66 decrease slightly compared with that of UiO-66 and was ascribed to the encapsulation of Ru NPs in the UiO-66 skeleton. The results of plasma-assisted catalytic CO2 methanation indicate that Ru@UiO-66 exhibits excellent catalytic activity. CO2 conversion and CH4 selectivity over Ru@UiO-66 reached 72.2% and 95.4% under 13.0 W of discharge power and a 30 mL·min−1 gas flow rate ( V H 2 : V C O 2 = 4 : 1 ), respectively. Both values are significantly higher than pure UiO-66 with plasma and Ru/Al2O3 with plasma. The enhanced performance of Ru@UiO-66 is attributed to its unique framework structure and excellent dispersion of Ru NPs.

scholarly journals Photocatalytic Performance and Degradation Pathway of Rhodamine B with TS-1/C3N4 Composite under Visible Light

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 756 ◽  
Author(s):  
Jingjing Yang ◽  
Hongqing Zhu ◽  
Yuan Peng ◽  
Pengxi Li ◽  
Shuyan Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photocatalytic Degradation ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Degradation Products ◽  
Nitrogen Adsorption ◽  
Degradation Pathway ◽  
Active Species ◽  
Photogenerated Electrons

TS-1/C3N4 composites were prepared by calcining the precursors with cooling crystallization method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), UV-Vis diffuse reflection spectrum (DRS) and nitrogen adsorption–desorption isotherm. The photocatalytic performance of TS-1/C3N4 composites was investigated to degrade Rhodamine B (RhB) under visible light irradiation. The results showed that all composites exhibited better photocatalytic performance than pristine TS-1 and C3N4; TS-1/C3N4-B composite (the measured mass ratio of TS-1 to C3N4 is 1:4) had best performance, with a rate constant of 0.04166 min−1, which is about two and ten times higher than those of C3N4 and TS-1, respectively. We attributed the enhanced photocatalytic performance of TC-B to the optimized heterostructure formed by TS-1 and C3N4 with proper proportion. From the results of photoluminescence spectra (PL) and the enhanced photocurrent, it is concluded that photogenerated electrons and holes were separated more effectively in TS-1/C3N4 composites. The contribution of the three main active species for photocatalytic degradation followed a decreasing order of ·O2−, ·OH and h+. The degradation products of RhB were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS), and the possible photocatalytic degradation pathways were proposed.

Synthesis of MoS2/TiO2 Nanophotocatalyst and Its Enhanced Visible Light Driven Photocatalytic Performance

2019 ◽  
Vol 19 (6) ◽  
pp. 3519-3527 ◽  
Author(s):  
Wei Teng ◽  
Youmei Wang ◽  
Qin Lin ◽  
Hui Zhu ◽  
Yubin Tang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Irradiation Time ◽  
Metal Sulfide ◽  
Active Species ◽  
X Ray ◽  
Radical Trapping ◽  
Layered Transition Metal

Molybdenum disulfide (MoS2), as a typical layered transition metal sulfide, has been widely used in photocatalysis. Here, we report layered MoS2 nanosheet-coated TiO2 heterostructures that were prepared using a simple photo-assisted deposition method. The as-prepared samples were investigated in detail by using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Results demonstrated that the MoS2 nanosheets uniformly covered the outer surface of TiO2. The visible light-sensitive photocatalytic activity was evaluated by the removal of methylene blue (MB) and 2-chlorophenol (2-CP) in aqueous solution. Thus, the MoS2/TiO2 heterostructures exhibited improved photocatalytic degradation activity under visible light compared with the pure TiO2. Under visible light irradiation for 90 min, the degradation efficiencies of MB and 2-CP over the MoS2/TiO2 sample (sunlight irradiation time: 30 min) are as high as 93.6% and 70.6%, respectively. Furthermore, the corresponding mechanism of enhanced photocatalytic activity is proposed on the basis of the comprehensively investigated results from the radical trapping experiments, photoluminescence spectroscopy, and electron spin resonance analysis. The hole oxidation, hydroxyl radicals, and superoxide anion radicals act as the active species simultaneously in the photodegradation of the dye molecules. However, of these species, hole oxidation played the most important roles in the photocatalytic reaction.

scholarly journals Mesoporous LaFeO3: Synergistic Effect of Adsorption and Visible Light Photo-Fenton Processes for Phenol Removal from Refinery Wastewater

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Thi To Nga Phan ◽  
Hong Lien Nguyen ◽  
Van Tuyen Le ◽  
Chi Nhan Phan ◽  
Thanh Huyen Pham
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Catalytic Mechanism ◽  
Light Irradiation ◽  
Phenol Removal ◽  
Hard Template ◽  
X Ray

Mesoporous LaFeO3 as a visible light-driven photocatalyst was prepared by a nanocasting method using mesoporous silica (SBA-15) as a hard template. The as-prepared LaFeO3 photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), and optical absorption spectra. The characterization studies and experimental results showed that LaFeO3 with porous structure caused by the removal of SBA-15 hard template could enhance the specific surface area of the resulting photocatalyst, which improves the phenol adsorption ability of the photocatalyst and in turn enhances its photo-Fenton catalytic activity. The photo-Fenton catalytic activity of the photocatalyst was investigated by photo-Fenton degradation of aqueous phenol under visible light irradiation. The effects of catalyst dosage, H2O2 concentration, and solution pH on the photo-Fenton catalytic degradation of phenol using mesoporous LaFeO3 were studied and optimized. Under the optimal conditions of 20 mg L−1 phenol, 1.0 g L−1 catalyst, and 10 mM H2O2 at pH = 5, the photo-Fenton degradation of phenol (93.47%) was achieved in 180 min under visible light irradiation. Furthermore, our results proved the stability and reusability of mesoporous LaFeO3 and revealed its catalytic mechanism for the photo-Fenton degradation of phenol.

scholarly journals Reduced graphene oxide supported C3N4 nanoflakes and quantum dots as metal-free catalysts for visible light assisted CO2 reduction

2019 ◽  
Vol 10 ◽  
pp. 448-458 ◽  
Author(s):  
Md Rakibuddin ◽  
Haekyoung Kim
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Visible Light ◽  
Reduced Graphene Oxide ◽  
Hybrid Materials ◽  
Photoelectron Spectroscopy ◽  
X Ray ◽  
Metal Free ◽  
Reduced Graphene ◽  
Vis Spectroscopy

The visible light photocatalytic reduction of CO2 to fuel is crucial for the sustainable development of energy resources. In our present work, we report the synthesis of novel reduced graphene oxide (rGO)-supported C3N4 nanoflake (NF) and quantum dot (QD) hybrid materials (GCN) for visible light induced reduction of CO2. The C3N4 NFs and QDs are prepared by acid treatment of C3N4 nanosheets followed by ultrasonication and hydrothermal heating at 130–190 °C for 5−20 h. It is observed that hydrothermal exposure of acid-treated graphitic carbon nitride (g-C3N4) nanosheets at low temperature generated larger NFs, whereas QDs are formed at higher temperatures. The formation of GCN hybrid materials was confirmed by powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy (TEM), and UV–vis spectroscopy. High-resolution TEM images clearly show that C3N4 QDs (average diameter of 2–3 nm) and NFs (≈20–45 nm) are distributed on the rGO surface within the GCN hybrid material. Among the as-prepared GCN hybrid materials, GCN-5 QDs exhibit excellent CO2 reductive activity for the generation of formaldehyde, HCHO (10.3 mmol h−1 g−1). Therefore, utilization of metal-free carbon-based GCN hybrid materials could be very promising for CO2 photoreduction because of their excellent activity and environmental sustainability.

HIGHLY CATALYTIC Ag/Co3O4 NANOCATALYSTS FABRICATED FOR RhB DYE DEGRADATION THROUGH A SIMPLE SILVER-MIRROR REACTION UNDER VISIBLE LIGHT

NANO ◽  
2014 ◽  
Vol 09 (08) ◽  
pp. 1450090 ◽  
Author(s):  
XIAOLEI SI ◽  
GUANGLIANG CHEN ◽  
ZHILI CHEN ◽  
JUN HUANG ◽  
SHIHUA CHEN ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Ag Nanoparticles ◽  
Dye Degradation ◽  
Precipitation Method ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Silver Mirror ◽  
Silver Mirror Reaction

In this paper, a highly catalytic and nanosized Ag / Co 3 O 4 composite for rhodamine B ( RhB ) degradation was fabricated by using the co-precipitation method at room temperature. The Ag / Co 3 O 4 structure and catalytic properties were characterized through scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) gas-sorption measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-Vis spectroscopy. The results showed that the Co 3 O 4 nanosheets prepared by hydrothermal synthesis mainly exposed (2 2 0) and (1 1 1) facets, which played an important role in determining its catalytic oxidation performance. The Co 3 O 4 nanosheets doped with Ag nanoparticles by a simple silver-mirror reaction exhibited a stable and well-dispersed property in dye solution. Compared to the Ag and Co 3 O 4 nanostructure, the Ag nanoparticles with bigger diameter (10 nm) on Co 3 O 4 surface also readily produced surface-active oxygen species and exhibited a higher catalytic activity for the degradation of RhB solution (5 mg ⋅ L-1) under the visible light. The kinetic constant K of Ag / Co 3 O 4 catalyst for RhB degradation reaction was evaluated to 0.02724 min-1, which is relatively higher than those reported in the literatures.

scholarly journals Photosensitization of Carbon Nitride Photoelectrodes with CdS: A Novel Architecture with Highly Efficient Photocatalytic Activity

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Xiaosong Zhou ◽  
Fei Yang ◽  
Bei Jin ◽  
Tang Xu ◽  
Yaqing Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Carbon Nitride ◽  
Light Irradiation ◽  
Diffuse Reflection Spectroscopy ◽  
X Ray ◽  
Acid Orange Ii

CdS with well-defined crystallinity is anchored on carbon nitride photoelectrodes by a successive chemical bath deposition. And the as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy techniques. The effect of the amount of CdS on the catalytic activity for the degradation of acid Orange II is investigated under visible light irradiation. Results show that the photoelectrodes composed of CdS/CN exhibit much higher catalytic activity than pure CN photoelectrodes. A possible photocatalytic mechanism of the CdS/CN electrodes is proposed under visible light irradiation.

A new core–shell Z-scheme heterojunction structured La(OH)3@In2S3 composite with superior photocatalytic performance

2021 ◽  
Vol 127 (2) ◽  
Author(s):  
Shuting Hu ◽  
Junfeng He ◽  
Fuming Chen ◽  
Bin Liu ◽  
Wangjian zhai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Performance ◽  
Electrochemical Impedance ◽  
Cost Effective ◽  
Active Species ◽  
X Ray ◽  
Methylene Orange ◽  
Photodegradation Rate ◽  
Redox Ability

AbstractConstructing Z-scheme heterojunction photocatalyst with strong redox ability to make for enhanced photocatalytic performance and efficient charge separation is extremely attractive but still underdeveloped. Herein, a Z-scheme heterojunction structured La(OH)3@In2S3 composite (labeled by “LIS”) with photocatalytic for the methylene orange (MO) degradation under simulated light irradiation has been developed. The as-prepared LIS, together with commercial La(OH)3 and pure In2S3 fabricated with the identical processing method and starting materials as those of LIS, was characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectra and electrochemical impedance spectroscopy. The results show the heterojunction of La(OH)3/In2S3 has prolonged the lifetime of the photo-generated carriers. The photocatalytic activity test shows that over only a small amount (0.02 g in 100 ml MO) of LIS, the photodegradation rate of 95% toward MO can be obtained in 90 min, which is about 3.4 times higher than that over pure In2S3. The active species trapping experiments indicate that there were four active species playing roles in photodegradation as the following order: e– = ∙OH < h+ < ∙O2–. A mechanism of Z-scheme heterojunction was proposed and well explained the enhanced photocatalytic performance. This work provides a new cost-effective photocatalyst with high photocatalytic properties.

Preparation and Photo-catalytic Activity of Cu-Supported Nano-TiO2

2020 ◽  
Vol 1 (1) ◽  
pp. 38-42
Author(s):  
Jun Yan
Keyword(s):  
Catalytic Activity ◽  
Methyl Orange ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Nano Tio2 ◽  
Hydrolysis Method ◽  
Response Range ◽  
Photo Response ◽  
Forced Hydrolysis ◽  
Visible Photocatalytic Activity

Cu-supported nano-TiO2 catalyst was prepared by forced hydrolysis method under mild condition. The morphology, composition and optical absorption properties of the samples were characterized by means of scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis diffuse reflectance spectroscopy (UV-VIS DRS). Visible photocatalytic activity of the samples was investigated by photocatalytic degradation experiment on methyl orange. The results indicated that nano-TiO2 was about 20nm in size with the main form of anatase, and photo response range was significantly broadened after it was loaded on the surface of Cu. The sample possessed high visible light catalytic activity, with the degradation rate of methyl orange reaching 94% under simulated natural light.

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