References of "Páez Martínez, Carlos"
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See detailInteractions between Zn2+ or ZnO with TiO2 to produce an efficient photocatalytic, superhydrophilic and aesthetic glass
Léonard, Géraldine ULiege; Pàez Martinez, Carlos ULiege; Ramirez, Alfonso et al

in Journal of Photochemistry and Photobiology A : Chemistry (2018), 350

Zinc was coupled with titanium dioxide using different methods. SiO2 and Zn-SiO2 doped TiO2 films, on the one hand, and Zn doped TiO2 on the other hand, have been produced using controlled sol-gel ... [more ▼]

Zinc was coupled with titanium dioxide using different methods. SiO2 and Zn-SiO2 doped TiO2 films, on the one hand, and Zn doped TiO2 on the other hand, have been produced using controlled sol-gel processes by alcoholic, cogelation and aqueous ways. From these syntheses, films were deposited on soda lime glass. These samples were compared to ZnO samples but also to bilayer samples constituting one layer of TiO2 and one layer of ZnO. The physico-chemical properties of the films were characterized by grazing-incidence X-ray diffraction, profilometry and UV-Vis absorption analyses. The photocatalytic activity has been evaluated from the degradation of methylene blue under UV-A light, from the degradation of p-nitrophenol under visible light and from the degradation of H2O2 under halogen light (UV-A + visible light). Superhydrophilicity was evaluated from contact angle measurement after UV exposition and also from hysteresis effects. Finally, a haze measurement was performed to evaluate the impact of the coating on the aesthetic property of the coated glass. Aqueous films have better photocatalytic activity and superhydrophilicity than samples from alcoholic synthesis. The crystallization of the sample appears to be one key factor: alcoholic films required calcination to ensure the crystallization of TiO2, but the alkali migration from the glass support prevents this crystallisation, while aqueous synthesis promotes crystallized particles at low temperatures without alkali interference. It appears that the relative activity from one sample to another depends on the nature of the illumination and on the nature of the molecule to be degraded. Nevertheless, the sample with ZnO layer deposited on first TiO2 layer (ZnO 500 Alc/TiO2 100 AQ) composite is found to be the best sample, maintaining a high hydrophilicity similar to TiO2 and a good activity. [less ▲]

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See detailVisible-light TiO2 photocatalyst doped with silylated porphyrin
Mahy, Julien ULiege; Pàez Martinez, Carlos ULiege; Léonard, Géraldine ULiege et al

Conference (2017, August 15)

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See detailCharacterization of photoactive coatings of SiO2 nanoparticles and Rose Bengal onto glass surfaces
Mendoza Gallego, Carlos ULiege; Lismont, Marjorie ULiege; Pàez Martinez, Carlos ULiege et al

Conference (2016)

The fluorescence emission and singlet oxygen (1O2) production have been widely investigated over the last decade due to high-value added applications such as organic chemical synthesis1, wastewater ... [more ▼]

The fluorescence emission and singlet oxygen (1O2) production have been widely investigated over the last decade due to high-value added applications such as organic chemical synthesis1, wastewater treatment2 or photodynamic cancer therapy3. This work is dedicated to the synthesis and deposition of SiO2 nanoparticles on glass surfaces using Stober’s process and dip coating, respectively. The adherence was improved through the incorporation of different concentrations of these nanoparticles into a TiO2 matrix. Additionally, the speed of dip coating was used to modify SiO2 thicknesses. Rose bengal was covalently anchored to SiO2 coatings through (3-aminopropyl)triethoxysilane (APTES) linker. UV, IR, fluorescence, SEM and profilometry were used to characterize the corresponding films and the efficiency for singlet oxygen production was measured by oxidation of the amino acid methionine. The immobilization of SiO2 nanoparticles photosensitized with rose bengal showed promising results for the production of singlet oxygen. [less ▲]

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See detailMethod for the wet deposition of thin films
Pàez Martinez, Carlos ULiege; Liquet, Dimitri ULiege; Calberg, Cédric ULiege et al

Patent (2016)

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See detailProtoporphyrin IX Functionalised AgSiO2 Core-shell Nanoparticle: Plasmonic Enhancement of Fluorescence and Singlet Oxygen Production
Lismont, Marjorie ULiege; Dreesen, Laurent ULiege; Heinrichs, Benoît ULiege et al

in Photochemistry & Photobiology (2016), 92

Metal-enhanced processes arising from the coupling of a dye with metallic nanoparticles (NPs) have been widely reported. However, few studies have simultaneously investigated these mechanisms from the ... [more ▼]

Metal-enhanced processes arising from the coupling of a dye with metallic nanoparticles (NPs) have been widely reported. However, few studies have simultaneously investigated these mechanisms from the viewpoint of dye fluorescence and photoactivity. Herein, protoporphyrin IX (PpIX) is grafted onto the surface of silver core silica shell NPs in order to investigate the effect of silver (Ag) localized surface plasmon resonance (LSPR) on PpIX fluorescence and PpIX singlet oxygen (1O2) production. Using two Ag core sizes, we report a systematic study of these photophysical processes as a function of silica (SiO2) spacer thickness, LSPR band position and excitation wavelength. The excitation of Ag NP LSPR, which overlaps the PpIX absorption band, leads to the concomitant enhancement of PpIX fluorescence and 1O2 production independently of the Ag core size, but in a more pronounced way for larger Ag cores. These enhancements result from the increase in the PpIX excitation rate through the LSPR excitation and decrease when the distance between PpIX and Ag NPs increases. A maximum fluorescence enhancement of up to 14-fold, together with an increase in photogenerated 1O2 production of up to five times are obtained using 100 nm Ag cores coated with a 5 nm thick silica coating. [less ▲]

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See detailPhotocatalytic decomposition of hydrogen peroxide over nanoparticles of TiO2 and Ni(II)-porphyrin doped TiO2: a relationship between activity and porphyrin anchoring mode
Tasseroul, Ludivine ULiege; Pàez Martinez, Carlos ULiege; Lambert, Stéphanie ULiege et al

in Applied Catalysis B : Environmental (2016), 182

The nickel tetra(4-carboxyphenyl)porphyrin (TCPPNi) was chimisorbed on Degussa P25 TiO2 at different concentrations. Diffuse reflectance spectroscopy in the UV/vis region, Fourier transform infrared ... [more ▼]

The nickel tetra(4-carboxyphenyl)porphyrin (TCPPNi) was chimisorbed on Degussa P25 TiO2 at different concentrations. Diffuse reflectance spectroscopy in the UV/vis region, Fourier transform infrared spectroscopy and thermal gravimetry combined with differential scanning calorimetry measurements allowed the determination of the TCPPNi anchoring mode. At low TCPPNi concentrations, this anchoring on Degussa P25 TiO2 took place through all four carboxylic groups, while at higher concentrations the anchoring occurred through one or two carboxylic groups. For the firsttime,the effect of UV/vis light irradiation on the H2O2-degradation activity of TiO2 and TCPPNi-doped TiO2 was studied using the method of following the production of O2 by gas pressure monitoring. The activity of seven different catalysts was related to the TCPPNi anchoring mode and the percentage of TiO2 Degussa P25 coverage. An optimum degradation of H2O2 was observed for 0.0115 mol TCPPNi × g−1 P25. In that case, the TCPPNi was anchored through the four carboxylic groups, corresponding to a strong interaction with Degussa P25 TiO2. Moreover, the TCPPNi did not cover the surface completely, therefore allowing the light to reach and activate the TiO2. [less ▲]

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See detailDegradation of p-nitrophenol and bacteria with TiO2 xerogels sensitized in situ with tetra(4-carboxyphenyl)porphyrins
Tasseroul, Ludivine ULiege; Lambert, Stéphanie ULiege; Eskenazi, David et al

Poster (2015, September 10)

Heterogeneous photocatalysis is widely studied for environmental applications as oxidative processes can completely destroy organic pollutants such as alkanes, pesticides, dyes, etc. and microorganisms ... [more ▼]

Heterogeneous photocatalysis is widely studied for environmental applications as oxidative processes can completely destroy organic pollutants such as alkanes, pesticides, dyes, etc. and microorganisms. The most used photocatalyst is the commercial TiO2 Degussa P25, which is composed of 80% anatase and 20% rutile and which is active when TiO2 is exposed to UV light ( < 380 nm). Recently, several studies have been performed to extend the light absorption range of TiO2 towards the visible range. In this study, TiO2-based materials doped with porphyrins, a widely used dye for the photosensibilization of TiO2, have been prepared using a sol-gel process. To stabilize the TiO2-dye interactions, free metal tetra(4-carboxyphenyl)porphyrin and nickel tetra(4-carboxyphenyl)porphyrin were introduced in situ into the TiO2 matrix during the sol-gel process rather than by grafting. Samples were thoroughly characterized by TEM, X-ray diffraction, FT-IR, DR-UV/Vis and their texture has been examined by nitrogen adsorption–desorption at 77 K. The photocatalytic activity for the degradation of p-nitrophenol and Escherichia coli and Lactobacillus rhamnosus bacteria cells in aqueous medium, under halogen lamp light have been evaluated in relation with the physico-chemical modifications induced by the doping. The low temperature vacuum drying protocol (150°C) used in the present study enabled to obtain porphyrin doped TiO2 xerogels with a high specific surface area, and containing nanoparticles composed of amorphous- and anatase-TiO2. Diffuse reflectance spectroscopy attest the presence of TCPPH2 and TCPPNi within the TiO2 matrix. In a first step, the photoactivity of the xerogels is tested for p-nitrophenol degradation. Results show that crystallinity and nature and concentration of porphyrin introduced in situ have major impact on the degradation performances. In a second step, the best xerogel for p-nitrophenol degradation has been used to degrade bacteria. This xerogel degrades E. coli and L. rhamnosus bacteria cells in less than 48 and 24 h respectively. The photocatalytic degradation of a pollutant is thus correlated to the degradation of bacteria since a xerogel doped with the TCPPNi degrades both p-nitrophenol, E. coli and L. rhamnosus. [less ▲]

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See detailWet method for the production of thin films (2)
Liquet, Dimitri ULiege; Calberg, Cédric ULiege; Eskenazi, David et al

Patent (2015)

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See detailWet method for the production of thin films (1)
Liquet, Dimitri ULiege; Calberg, Cédric ULiege; Eskenazi, David et al

Patent (2015)

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See detailCore-shell AgSiO2-Protoporphyrin IX nanoparticle: Effect of the Ag core on reactive oxygen species generation
Lismont, Marjorie ULiege; Pàez Martinez, Carlos ULiege; Dreesen, Laurent ULiege

in SPIE proceeding - Colloidal Nanoparticles for Biomedical Applications X (2015, February)

Photodynamic therapy (PDT) for cancer is based on the use of a light sensitive molecule to produce, under specific irradiation, toxic reactive oxygen species (ROS). A way to improve the therapy efficiency ... [more ▼]

Photodynamic therapy (PDT) for cancer is based on the use of a light sensitive molecule to produce, under specific irradiation, toxic reactive oxygen species (ROS). A way to improve the therapy efficiency is to increase the amount of produced ROS near cancer cells. This aim can be achieved by using a metal enhanced process arising when an optically active molecule is located near a metallic nanoparticle (NP). Here, the coupling effect between silver (Ag) NPs and protoporphyrin IX (PpIX) molecules, a clinically approved photosensitizer, is studied compared first, to PpIX fluorescence yield and second, to ROS production efficiency. By applying a modified Stöber process, PpIX was encapsulated into a silica (SiO2) shell, surrounding a 60 nm sized Ag core. We showed that, compared to SiO2-PpIX NPs, Ag coated SiO2-PpIX NPs dramatically decreased PpIX fluorescence together with singlet oxygen production efficiency. However, after incubation time in the dark, the amount of superoxide anions generated by the Ag doped sample was higher than the control sample one. [less ▲]

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See detailA one-step short-time synthesis of Ag@SiO2 core-shell nanoparticles
Lismont, Marjorie ULiege; Pàez Martinez, Carlos ULiege; Dreesen, Laurent ULiege

in Journal of Colloid & Interface Science (2015)

A performance of shell-thickness precise control in silver-silica coating core-shell nanoparticles is presented. 60 nm sized citrate-stabilized silver nanoparticles are directly silica coated using a ... [more ▼]

A performance of shell-thickness precise control in silver-silica coating core-shell nanoparticles is presented. 60 nm sized citrate-stabilized silver nanoparticles are directly silica coated using a modified Stöber process. Tetraethyl orthosilicate is used as a silica precursor and ammonium hydroxide as catalyst in an alcoholic solvent to promote the seeded silica growth. By simply varying the synthesis reaction time from 4 to 60 minutes, the silica shell thickness is increased from 5.1 nm to 76.4 nm. This well-controlled synthesis is then transposed to 40, 80 and 100 nm sized silver cores in order to show the independence of the silica shell growth on the nanoparticle core size. Optical properties, i.e. localized surface plasmon resonance, of the produced silver-silica core-shell are also investigated. [less ▲]

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See detailThe range of validity of sorption kinetic models
Douven, Sigrid ULiege; Pàez Martinez, Carlos ULiege; Gommes, Cédric ULiege

in Journal of Colloid & Interface Science (2015), 448

Several hundred papers are published yearly reporting liquid-phase adsorption kinetics data. In general the data is analyzed using a variety of standard models such as the pseudo first- and second-order ... [more ▼]

Several hundred papers are published yearly reporting liquid-phase adsorption kinetics data. In general the data is analyzed using a variety of standard models such as the pseudo first- and second-order models and the Intraparticle-Diffusion model. The validity of these models is often assessed empirically via their ability to fit the data, independently of their physicochemical soundness. The aim of the present paper is to rationalize the analysis of liquid-phase adsorption kinetics data, and to investigate experimental factors that influence the adsorption kinetics, in addition to the characteristics of the adsorbent material itself. For that purpose we use a simple Langmuir adsorption–diffusion model, which enables us to identify three dimensionless numbers that characterize the working regime of any batch adsorption experiment: an adsorption Thiele modulus, a saturation modulus, and a loading modulus. The standard models are found to be particular cases of the general adsorption–diffusion model for specific values of the dimensionless numbers. This provides sound physicochemical criteria for the validity of the models. Based on our modeling, we also propose a general yet simple data analysis procedure to practically estimate the diffusion coefficient in adsorbent pellets starting from adsorption halftimes. [less ▲]

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See detailPhotocatalytic degradation of water pollutants with visible light-sensitized TiO2 xerogels
Tasseroul, Ludivine ULiege; Pirard, Sophie ULiege; Lambert, Stéphanie ULiege et al

in Récents Progrès en Génie des Procédés (2014), 106

To extend its photocatalytic activity to visible light, TiO2 has been doped in situ through the cogelation sol-gel proces with two dyes : free metal tetra(4-carboxyphenyl)porphyrin and nickel tetra(4 ... [more ▼]

To extend its photocatalytic activity to visible light, TiO2 has been doped in situ through the cogelation sol-gel proces with two dyes : free metal tetra(4-carboxyphenyl)porphyrin and nickel tetra(4-carboxyphenyl)porphyrin. DR and FT-IR spectroscopies have been performed to determine the interaction between porphyrins and TiO2. Cristallinity and specific surface area have been measured by XRD and N2 adsorption. The photoactivity of the doped TiO2 xerogels has been evaluated for p-nitrophenol (a model water pollutant) degradation under visible light and a kinetic study has been performed. The samples allow the degradation of 40% of p-nitrophenol in 6 h which makes them very promising for water decontamination under natural light. A kinetic study of p-nitrophenol degradation with the Ni-doped catalyst has shown that the best kinetic model involves one type of active site corresponding to the hole h+ of electron-hole pairs created at the TiO2 surface by light. The rate determining step consists of the surface reaction between adsorbed p-nitrophenol and adsorbed OH• radicals. [less ▲]

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See detailProcess for manufacturing a composite material
Liquet, Dimitri ULiege; Pàez Martinez, Carlos ULiege; Calberg, Cédric ULiege et al

Patent (2013)

Detailed reference viewed: 191 (65 ULiège)