scholarly journals Photocatalytic activity of graphene oxide–TiO 2 thin films sensitized by natural dyes extracted from Bactris guineensis

2019 ◽  
Vol 6 (3) ◽  
pp. 181824 ◽  
Author(s):  
William Vallejo ◽  
Angie Rueda ◽  
Carlos Díaz-Uribe ◽  
Carlos Grande ◽  
Patricia Quintana
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
Photocatalytic Degradation ◽  
Photoelectron Spectroscopy ◽  
Chemical Characterization ◽  
Sem Analysis ◽  
Visible Range ◽  
X Ray ◽  
Natural Sensitizer

This study synthesized and characterized composites of graphene oxide and TiO 2 (GO–TiO 2 ). GO–TiO 2 thin films were deposited using the doctor blade technique. Subsequently, the thin films were sensitized with a natural dye extracted from a Colombian source ( Bactris guineensis ). Thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance measurements were used for physico-chemical characterization. All the samples were polycrystalline in nature, and the diffraction signals corresponded to the TiO 2 anatase crystalline phase. Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) verified the synthesis of composite thin films, and the SEM analysis confirmed the TiO 2 films morphological modification after the process of GO incorporation and sensitization. XPS results suggested a possibility of appearance of titanium (III) through the formation of oxygen vacancies (O v ). Furthermore, the optical results indicated that the presence of the natural sensitizer and GO improved the optical properties of TiO 2 in the visible range. Finally, the photocatalytic degradation of methylene blue was studied under visible irradiation in aqueous solution, and pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. These results indicated that the presence of GO has an important synergistic effect in conjunction with the natural sensitizer, reaching a photocatalytic yield of 33%.

scholarly journals Methylene Blue Photodegradation under Visible Irradiation on Ag-Doped ZnO Thin Films

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
William Vallejo ◽  
Alvaro Cantillo ◽  
Carlos Díaz-Uribe
Keyword(s):  
Thin Films ◽  
Methylene Blue ◽  
Raman Spectroscopy ◽  
Photocatalytic Degradation ◽  
Physicochemical Characterization ◽  
Zno Thin Films ◽  
Visible Range ◽  
X Ray ◽  
Visible Irradiation ◽  
Doped Zno

This study synthesized and characterized Ag-doped ZnO thin films. Doped ZnO powders were synthesized using the sol-gel method, and thin films were fabricated using the doctor blade technique. The Ag content was determined by optical emission spectrometers with inductively coupled plasma (ICP plasma). Additionally, X-ray diffraction, Raman spectroscopy, Atomic Force Microscopy (AFM), diffuse reflectance, and X-ray photoelectron spectroscopy (XPS) measurements were used for physicochemical characterization. Finally, the photocatalytic degradation of methylene blue (MB) was studied under visible irradiation in aqueous solution. The Langmuir-Hinshelwood model was used to determine the reaction rate constant of the photocatalytic degradation. The physicochemical characterization showed that the samples were polycrystalline, and the diffraction signals corresponded to the ZnO wurtzite crystalline phase. Raman spectroscopy verified the ZnO doping process. The AFM analysis showed that roughness and grain size were reduced after the doping process. Furthermore, the optical results indicated that the presence of Ag improved the ZnO optical properties in the visible range, and the Ag-doped ZnO thin films had the lowest band gap value (2.95 eV). Finally, the photocatalytic degradation results indicated that the doping process enhanced the photocatalytic activity under visible irradiation, and the Ag-doped ZnO thin films had the highest MB photodegradation value (45.1%), as compared to that of the ZnO thin films (2.7%).

scholarly journals X-ray Photoelectron Spectroscopy Analysis of Chitosan–Graphene Oxide-Based Composite Thin Films for Potential Optical Sensing Applications

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 478
Author(s):  
Wan Mohd Ebtisyam Mustaqim Mohd Daniyal ◽  
Yap Wing Fen ◽  
Silvan Saleviter ◽  
Narong Chanlek ◽  
Hideki Nakajima ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Functional Group ◽  
Optical Sensing ◽  
Composite Thin Films ◽  
Cobalt Ions ◽  
X Ray ◽  
Sensing Applications

In this study, X-ray photoelectron spectroscopy (XPS) was used to study chitosan–graphene oxide (chitosan–GO) incorporated with 4-(2-pyridylazo)resorcinol (PAR) and cadmium sulfide quantum dot (CdS QD) composite thin films for the potential optical sensing of cobalt ions (Co2+). From the XPS results, it was confirmed that carbon, oxygen, and nitrogen elements existed on the PAR–chitosan–GO thin film, while for CdS QD–chitosan–GO, the existence of carbon, oxygen, cadmium, nitrogen, and sulfur were confirmed. Further deconvolution of each element using the Gaussian–Lorentzian curve fitting program revealed the sub-peak component of each element and hence the corresponding functional group was identified. Next, investigation using surface plasmon resonance (SPR) optical sensor proved that both chitosan–GO-based thin films were able to detect Co2+ as low as 0.01 ppm for both composite thin films, while the PAR had the higher binding affinity. The interaction of the Co2+ with the thin films was characterized again using XPS to confirm the functional group involved during the reaction. The XPS results proved that primary amino in the PAR–chitosan–GO thin film contributed more important role for the reaction with Co2+, as in agreement with the SPR results.

Study on integration of aluminum-doped zinc oxide (AZO) thin films with graphene oxide (GO)

2018 ◽  
Vol 32 (19) ◽  
pp. 1840044
Author(s):  
Aditya Dalal ◽  
Animesh Mandal ◽  
Shubhada Adhi ◽  
Kiran Adhi
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Aluminum Doped Zinc Oxide ◽  
Uv Visible

Aluminum (0.5 at.%)-doped ZnO (AZO) thin films were deposited by pulsed laser deposition technique (PLD) in oxygen ambient of 10[Formula: see text] Torr. The deposited thin films were characterized by x-ray diffraction (XRD), photoluminescence (PL), Raman spectroscopy and uv–visible spectroscopy (UV–vis). Next, graphene oxide (GO) was synthesized by Hummers method and was characterized by XRD, UV–vis spectroscopy, Raman spectroscopy and transmission electron microscopy (TEM). Thereafter, GO solution was drop-casted on AZO thin films. These films were then characterized by Raman Spectroscopy, UV–vis spectroscopy and PL. Attempt is being made to comprehend the modifications in properties brought about by integration.

scholarly journals Photocatalytic Activity of Ag-TiO2 Composites Deposited by Photoreduction under UV Irradiation

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Carlos Díaz-Uribe ◽  
Jose Viloria ◽  
Lorraine Cervantes ◽  
William Vallejo ◽  
Karen Navarro ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Photocatalytic Activity ◽  
Photocatalytic Degradation ◽  
Uv Irradiation ◽  
Ag Nanoparticles ◽  
Nitrate Solution ◽  
Physicochemical Characterization ◽  
Soda Lime Glass ◽  
X Ray

In this work, we synthesized Ag nanoparticles on TiO2 thin films deposited on soda lime glass substrates. Ag nanoparticles were synthesized by photoreduction under UV irradiation silver nitrate solution. X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) measurements were used for physicochemical characterization. The structural study showed that all samples were polycrystalline, main phases were anatase and rutile, and no additional signals were detected after surface modification. Raman spectroscopy suggested that silver aggregates deposited on the TiO2 films could exhibit the surface plasmon resonance (SPR) phenomenon; XPS and SEM analysis confirmed TiO2 film morphological modification after photoreduction process. Photocatalytic degradation of methylene blue (MB) was studied under UV irradiation in aqueous solution, and, besides, pseudo-first-order model was used to obtain kinetic information about photocatalytic degradation. Results indicated that Ag-TiO2 showed an important increase in photocatalytic activity under UV (from 20% to 35%); finally, Ag-TiO2 thin films had kapp value 2.4 × 10−3 ± 0.003 min−1 of 1.8 times greater than the kapp value 1.3 × 10−4 ± 0.0004 min−1 of TiO2 thin films.

Nanostructure evolution and properties of two-phase nc-Ti(C, N)/a-(C, CNx) nanocomposites by high-resolution transmission electron microscopy, x-ray photoelectron spectroscopy, and Raman spectroscopy

2007 ◽  
Vol 22 (9) ◽  
pp. 2460-2469 ◽  
Author(s):  
Y.H. Lu ◽  
Y.G. Shen
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Solid Solution ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Atomic Ratio ◽  
Two Phase ◽  
X Ray ◽  
Transmission Electron

High-resolution transmission electron microscopy, x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to study phase configuration and nanostructure evolutions of Ti–Cx–Ny thin films with different amounts of C incorporation. It was found that the atomic ratio of (C + N)/Ti played a crucial role in phase configuration and nanostructure evolutions as well as mechanical behaviors. When the ratio was less than one unit, a nanocrystalline (nc-) Ti(C, N) solid solution was formed by way of dissolution of C into TiN lattice. When this dissolution reached saturation, precipitation of a small amount of amorphous (a-) C phase along nc-Ti(C, N) grains was followed with more C incorporation. Further increase of C content (up to ∼19 at.% C) made the amorphous phase fully wet nanocrystallites, which resulted in the formation of two-phase nanocomposite thin films with microstructures comprising of ∼5 nm nc-Ti(C,N) crystallites separated by ∼0.5 nm a-(C, CNx) phase. Thicker amorphous walls and smaller sized grains were followed when the C content was further increased, accompanying with the formation of some disorders and defects in nc-grains and amorphous matrices. When the C content was increased to ∼48 at.%, 1–3 nm nanocrystallites with an average size of ∼2 nm were embedded into amorphous matrices. Both microhardness and residual compressive stress values were increased with increase of the atomic ratio in solid solution thin films when the atomic ratio value was less than one unit. Their maximums were obtained at stiochiometry nc-Ti(C,N) solid solution. Enhancement of hardness values was attributed to solid solution effect.

scholarly journals Antibacterial Activity of Visible Light-Activated TiO2 Thin Films with Low Level of Fe Doping

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Dan Meng ◽  
Xiuhua Liu ◽  
Yun Xie ◽  
Yang Du ◽  
Yong Yang ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Antibacterial Activity ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Antibacterial Properties ◽  
Dip Coating ◽  
Tio2 Thin Films ◽  
X Ray

Development of effective antibacterial visible light-activated photocatalytic materials in industries including wastewater treatment and food industry has attracted increasing attention. In this work, Fe-doped TiO2 thin films with different doping levels on a glass substrate were prepared by the sol-gel dip-coating method. The as-prepared films were characterized by Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM). Raman spectroscopy and XRD results show the crystalline phase of titanium dioxide was anatase, and the range of the crystal size for the films was 19.24–22.24 nm. XPS results indicate that iron was in the form of Fe3+ in Fe-doped TiO2 films. Regarding the antibacterial properties of TiO2 films, the order of antibacterial activity of TiO2 films was 0.1 at% Fe > 0.5 at% Fe > 1.0 at% TiO2 > bare TiO2 > 2.0 at% Fe > 3.45 at% Fe. 0.1 at% of Fe is the optimum dopant ratio related to antibacterial activity. 0.1 at% Fe-doped TiO2 film is highly efficient in inactivating E. coli under 3 h of visible light irradiation, and it remains efficient even in real dye waste water.

scholarly journals Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy Statistical Analysis

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 769
Author(s):  
Roksana Muzyka ◽  
Sabina Drewniak ◽  
Tadeusz Pustelny ◽  
Marcin Sajdak ◽  
Łukasz Drewniak
Keyword(s):  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
Statistical Analysis ◽  
Reduced Graphene Oxide ◽  
Graphite Oxide ◽  
Photoelectron Spectroscopy ◽  
Graphene Oxides ◽  
Preparation Methods ◽  
X Ray ◽  
Reduced Graphene

In this paper, various graphite oxide (GO) and reduced graphene oxide (rGO) preparation methods are analyzed. The obtained materials differed in their properties, including (among others) their oxygen contents. The chemical and structural properties of graphite, graphite oxides, and reduced graphene oxides were previously investigated using Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). In this paper, hierarchical clustering analysis (HCA) and analysis of variance (ANOVA) were used to trace the directions of changes of the selected parameters relative to a preparation method of such oxides. We showed that the oxidation methods affected the physicochemical properties of the final products. The aim of the research was the statistical analysis of the selected properties in order to use this information to design graphene oxide materials with properties relevant for specific applications (i.e., in gas sensors).

scholarly journals Covalent Functionalization of Graphene Oxide with Fructose, Starch, and Micro-Cellulose by Sonochemistry

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 490
Author(s):  
María Montserrat Cruz-Benítez ◽  
Pablo Gónzalez-Morones ◽  
Ernesto Hernández-Hernández ◽  
José Roberto Villagómez-Ibarra ◽  
Javier Castro-Rosas ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Organic Molecules ◽  
Chemical Characterization ◽  
Covalent Bond ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultrasound Waves ◽  
Short Time

In this work, we report the synthesis of graphene oxide (GO) nanohybrids with starch, fructose, and micro-cellulose molecules by sonication in an aqueous medium at 90 °C and a short reaction time (30 min). The final product was washed with solvents to extract the nanohybrids and separate them from the organic molecules not grafted onto the GO surface. Nanohybrids were chemically characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy and analyzed by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray diffraction (XRD). These results indicate that the ultrasound energy promoted a chemical reaction between GO and the organic molecules in a short time (30 min). The chemical characterization of these nanohybrids confirms their covalent bond, obtaining a grafting percentage above 40% the weight in these nanohybrids. This hybridization creates nanometric and millimetric nanohybrid particles. In addition, the grafted organic molecules can be crystallized on GO films. Interference in the ultrasound waves of starch hybrids is due to the increase in viscosity, leading to a partial hybridization of GO with starch.

scholarly journals TiO2/Diazonium/Graphene Oxide Composites: Synthesis and Visible-Light-Driven Photocatalytic Degradation of Methylene Blue

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Nguyen Thi Vuong Hoan ◽  
Nguyen Ngoc Minh ◽  
Thoi Thi Kim Nhi ◽  
Nguyen Van Thang ◽  
Vu Anh Tuan ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Graphene Oxide ◽  
Photocatalytic Degradation ◽  
Photoelectron Spectroscopy ◽  
Diazonium Salt ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Visible Light Driven ◽  
Molecular Masses

In the present article, the synthesis of TiO2/diazonium/graphene oxide and its photocatalytic activity for methylene blue (MB) degradation have been demonstrated. The functionalization of graphene oxide (GO) with diazonium salt (diazonium-GO) was conducted for enhancing the dispersibility of GO in distilled water. TiO2 was highly dispersed in diazonium-GO to form TiO2/diazonium/graphene. The obtained specimens were characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, UV-Vis spectroscopy, scanning electron microscope, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was found that the TiO2 phase in TiO2/diazonium/GO composites can be controlled by adjusting the amount of ethanol or titanium oxide in the reactant mixture. The obtained composites exhibited photocatalytic activities for methylene blue degradation (MB). The composite with ac. 70% anatase can provide the highest MB degradation efficiency. The studying of some intermediates for MB photocatalytic degradation using LC-MS showed that structure of MB by the cleavage and oxidation of one or more of the methyl group substituent on the amine groups lead to form compounds with low molecular masses. Total organic carbon studies confirmed a complete mineralization of MB. The present catalyst was stable and recyclable after three times with a negligible loss of catalytic activity. In addition, the TiO2/diazonium/GO can also photocatalyze for the degradation of some other dyes (phenol, methyl red, and Congo red).

Preparation and Electrochromic Characterization of Nanocrystalline Nio-Base Thin Films

2011 ◽  
Vol 194-196 ◽  
pp. 2355-2364
Author(s):  
Lian Chao Wang
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Precursor Solution ◽  
Nickel Chloride ◽  
Dip Coating ◽  
Chloride Ions ◽  
Molar Ratio ◽  
Visible Range ◽  
Cyclic Voltammogram ◽  
X Ray

A precursor solution was prepared by dissolving anhydrous nickel chloride, anhydrous cobalt chloride and citric acid in butanol and ethanol. The solution was refluxed under continuous stirring, and then through hydrolyzing to change to a stable sol. To aerate dry NH3into the solution after being refluxed can deposit the chloride ions completely .The thin films were deposited by dip-coating method. The thin films were Characterized by atomic force microscopy (AFM), X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochromic performance of films were Characterized by means of electrochemical (cyclic voltammetry) measurements, and optical (transmittance) method. Results show that the thin films can transform from amorphous into cubic-NiO nanocrystalline heated at 280°С for 30 min and the xerogel powder must be heated at 300°С for 30 min. The results of films heated at different temperature show that the film heated below crystal temperature has a loose, island amorphous structure, and that of the films heated at 300°С has a compact, regular square structure. The results of cyclic voltammogram and transmittance spectra of films suggest that the molar ratio of Ni/Co=5 cobalt doped can obviously decrease the potential of oxidation and reduction reaction, and make the films present the lowest transmittance in visible range in colored state. The films prepared showed electrochromic reversibility only in crystal state. The film heated at 300°С for 30 min occurred the highest intensity of the peak of current density of oxidation and reduction..

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